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Handbook UFIREG Project
Ultrafine Particles - an evidence based contribution to the develop-
ment of regional and European environmental and health policy
(2011 – 2014)
This project is implemented through the CENTRAL EUROPE Programme co-financed by
the ERDF
UFIREG
Ultrafine Particles – an evidence based contribution to
the development of regional and European
environmental and health policy

Ultrafine Particles – an evidence based contribution to the development of regional and European
environmental and health policy (UFIREG).
This document was prepared by the consortium of the UFIREG project. For more information,
please visit the project website:
www.ufireg-central.eu
Handbook UFIREG Project
November 2014
© UFIREG Project 2014

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Handbook UFIREG Project
CONTENTS
Executive Summary ................................................................................................................................ 4
1 Background and Introduction ............................................................................................................. 6
Objectives of the UFIREG Project ..................................................................................................... 8
Project Description ............................................................................................................................. 8
2 Methods ............................................................................................................................................ 10
Measurements .................................................................................................................................. 10
Analysis of air quality data............................................................................................................... 11
Epidemiological data ........................................................................................................................ 12
Daily deaths and hospital admissions ............................................................................................... 12
Confounder variables ....................................................................................................................... 13
Sociodemographic data .................................................................................................................... 14
Epidemiological analysis.................................................................................................................. 14
3 Results .............................................................................................................................................. 15
Temporal and spatial variation of PNC in the UFIREG cities ......................................................... 15
Descriptive statistics of health data .................................................................................................. 23
Effects of ultrafine and fine particles on natural and cause-specific mortality ................................ 24
Effects of ultrafine and fine particles on cause-specific hospital admissions .................................. 26
4 Discussion and Conclusions ............................................................................................................. 27
5 Recommendations ............................................................................................................................ 28
Research ........................................................................................................................................... 29
Policymakers and stakeholders ........................................................................................................ 29
References ............................................................................................................................................. 31

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EXECUTIVE SUMMARY
Ultrafine particles - Invisible to our eyes, but detrimental to our health
Ultrafine particles (UFP) are the smallest constituents of airborne particulate matter: they are smaller
than 0.1 micrometres and invisible to our eyes. Yet, their potential adverse effects on human health are
of great concern because of their specific properties and acting mechanisms. Size governs the transport
and removal of particles from the air and their deposition within the respiratory system and it is partly
associated with the chemical composition and the source. UFP have little mass but high number and
surface area concentration and a high content of elemental and organic carbon. Ambient UFP are built
from gases or originate from combustion processes. In urban areas, they are emitted mostly by
anthropogenic sources like traffic, domestic heating, and industrial processes.
Epidemiological studies have shown that particulate matter (PM) is associated with adverse health
effects, especially in vulnerable population groups. Health effects of UFP are in part different from
effects of larger particles such as PM
2.5
or PM
10
as they deposit deeply in the lung and can for example
penetrate the lung membranes, reach the bloodstream and are transported to different organs such as
heart, liver, kidneys and brain. Evidence on short-term health effects of UFP, however, is still limited
and no epidemiological studies of long-term exposures to ambient UFP have been conducted yet.
The UFIREG project
The project “Ultrafine particles – an evidence based contribution to the development of regional and
European environmental and health policy” (UFIREG) started in July 2011 and ended in December
2014. It was implemented through the Central Europe Programme and co-financed by the ERDF. Five
cities in four Central European countries participated in the study: Augsburg (Germany), Chernivtsi
(Ukraine), Dresden (Germany), Ljubljana (Slovenia) and Prague (Czech Republic).
The aim of the UFIREG project was to improve the knowledge base on possible health effects of UFP
and to raise overall awareness of environmental and health care authorities and the population. The
project had two main areas of work: (1) exposure assessment to UFP and other air pollutants in the
five European cities and (2) epidemiological studies assessing short-term effects of these particles on
human cause-specific mortality and morbidity.
Exposure assessment
To investigate the exposure of the population to UFP, UFIREG partners have established standardised
UFP measurements using custom-made mobility particle size spectrometers in the five project cities.
The temporal variation of UFP was determined at one fixed monitoring site in each of the five project
cities. Overall, the particle number concentration (PNC) of 10-100 nm particles varied between the
five cities from May 2012 to April 2014. In summer, there was a considerable influence of new
particle formation due to high global radiation and precursor gases, especially in Dresden and Prague.
The results demonstrate that PNC in urban areas strongly depend on various factors such as the
activity of different particle sources (traffic, domestic heating, long-range transport, etc.) whereby the
everyday life of people plays an important role, meteorological conditions and cityscape. Overall, the
project results showed that high quality measurements of size-resolved PNC and integration into
routine monitoring networks are still a challenge.

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Epidemiological assessment
Epidemiological studies in the frame of the UFIREG project have assessed the short-term effects of
UFP on human mortality and morbidity, especially in relation to cardiovascular and respiratory
diseases. Official statistics were used to determine the association between air pollution concentration
and daily (cause-specific: respiratory and cardiovascular) hospital admissions and mortality.
Associations of UFP levels and health effects were analysed for each city by use of Poisson regression
models adjusting for a number of confounding factors. Results on morbidity and mortality effects of
UFP were heterogeneous across the five European cities investigated. Overall, an increase in
respiratory hospital admissions and mortality could be detected for increases in UFP concentrations.
Results on cardiovascular health were less conclusive.
There is still (a) limited epidemiological evidence on the effect of short-term exposure to UFP on
health; (b) insufficient understanding of whether the effects of UFP are independent of those of PM
2.5
and PM
10
; (c) no evidence on the effects of long-term exposure to UFP on health, and (d) little
evidence showing which size ranges or chemical characteristics of UFP are most significant to health.
Discussion and conclusions
It is still not possible to draw definite conclusions about the specific health consequences of exposure
to UFP. Further multi-centre studies such as UFIREG are needed preferably investigating several
years in order to produce powerful results. There are still few epidemiological studies investigating
adverse health effects of UFP.
Recommendations
The UFIREG project and other scientific studies have uncovered a number of knowledge gaps. The
project consortium is suggesting further pursuing open research questions. Further research is needed
to create more epidemiological evidence on the effect of short-term and long-term exposure to UFP on
health, to increase the understanding of whether the effects of UFP are independent of those of PM
2.5
and PM
10
, and to show which size ranges or chemical characteristics of UFP are most significant to
health.
So far, no directives for the regulation of UFP in ambient air and almost no official measurement sites
which routinely measure UFP exist. Even if further research is required to formulate guidelines or set
threshold, policymakers and stakeholders are called upon for supporting routine measurements and
research efforts as well as for developing and implementing measures to reduce UFP emissions,
particularly from transport and domestic heating/biomass burning, at this stage.

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Handbook UFIREG Project
1
BACKGROUND AND INTRODUCTION
Ultrafine particles (UFP) are defined as having a diameter of 100 nanometres (nm) and smaller. This
means that the size of an ultrafine particle is about 1/1000 of the diameter of a human hair (Figure 1).
Figure 1. Size comparisons of particulate matter (adapted from Brook et al., 2004).
Ambient UFP sources are mostly related to combustion processes (e.g. traffic-related, industrial or
from domestic heating). Motor vehicles are regarded as the leading source of UFP, especially in urban
areas. Due to their small size and little mass the deposition and clearance of UFP in the respiratory
tract is different compared to larger particles. Fine particles with an aerodynamic diameter < 10 μm
(PM
10
) or <2.5 μm (PM
2.5
) deposit mainly in the upper and lower airways, whereas UFP can proceed
deeply into the pulmonary alveoli (Figure 2).
Figure 2. Regional deposition of particles in the human respiratory tract (adapted from Kreyling et al.,
2006).

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Epidemiological studies have shown that particulate matter (PM) is associated with adverse health
effects (Rückerl et al., 2011) (Figure 3), especially in vulnerable population groups (Figure 4).
Figure 3. Organs of the human body that can be affected by air pollution (adapted from Peters et al.,
2011).
Figure 4. Stages in life of special susceptibility toward air pollution (adapted from Rückerl et al., 2011).
Toxicological studies suggest that inhaled UFP can pass the lung epithelium and translocate into the
blood to further be transported to other organs. Due to the differences in deposition and the potential
for translocation as well as their huge active surface, it is assumed that effects of UFP differ and might
be at least partly independent from those of larger particles such as PM
10
and PM
2.5
(Box 1). So far,
experimental studies do not provide sufficient evidence to confirm this hypothesis. Regarding health

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effects, there is suggestive, but not consistent epidemiological evidence on the association between
short-term exposures to UFP and cardiorespiratory health (WHO Regional Office for Europe, 2013;
HEI Review Panel on Ultrafine Particles, 2013). Moreover, no epidemiological studies of long-term
exposures to ambient UFP have been conducted yet.
Box 1.
Ultrafine Particles (Rückerl et al., 2011; Brook et al., 2004; HEI Review Panel on Ultrafine
Particles, 2013)
-
Deposit deeply in the lung.
-
Are not well recognized and cleared by the immune system in the alveolar space.
-
Injure cells, cause oxidative stress, inflammation, mitochondrial exhaustion, and damage to
protein and DNA.
-
Penetrate the lung membranes, reach the bloodstream and can be transported to different
organs such as heart, liver, kidneys and brain.
-
Reach the brain via the olfactory nerve.
So far, no directives exist for the regulation of UFP measurements in ambient air. One of the
conclusions of the WHO-REVIHAAP project (WHO Regional Office for Europe, 2013) was that the
scientific base is too small to work on a guideline for the number of UFP and to propose a guideline
value. Accordingly, in most locations UFP are not routinely monitored. However, scientists criticise
that there are no limit values for UFP in ambient air and they argue that the established limit values for
particulate matter (PM
10
or PM
2.5
) are not suitable for UFP because of their small size and mass. The
most common measurement of UFP concentration is to count the number of particles per unit volume
of air, which is typically referred to as particle number concentration (PNC). Thus, routine
measurements of PNC and development of limit values could be important for better air quality
control and for the prevention of potential adverse health effects.
Objectives of the UFIREG Project
The
main objective
of the UFIREG project was to assess UFP (and other air pollutant) concentrations
in five European cities, to analyse their spatial and temporal variability, and to investigate the short-
term effects of ultrafine and fine particles on mortality and hospital admissions in order to provide an
evidence based contribution to the development of environmental and health policy.
Moreover, the
specific aims
of the project were:
(1) to prepare a cost-efficient UFP measurement strategy applicable in all European regions,
(2) to demonstrate the applicability of the measurement strategy in the involved cities,
(3) to improve the overall sensitivity of the population as well as the environment and health care
authorities of the targeted regions to potential adverse health effects of UPF,
(4) to integrate results into regional political decision-making and concrete local measures by
developing differentiated solutions to the respective regional settings.
Project Description
The UFIREG project lasted from July 2011 to December 2014 and brought together a group of seven
institutions from four European countries (Germany, Czech Republic, Slovenia and Ukraine),
comprising experts in the fields of air pollution, epidemiology and public health. It was implemented

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Handbook UFIREG Project
through the CENTRAL EUROPE Programme co-financed by the ERDF.
The project aimed at improving the sensitivity of environment and health care authorities of targeted
regions to UFP and to encourage closer co-operation between involved actors in order to better protect
local populations from the negative health effects of exposure to UFP. Stakeholders from
governmental agencies, regional authorities and policy, health care agencies, and science joined the
project. The stakeholders were involved in order to integrate existing knowledge on UFP and
information gained during the UFIREG project in regional air pollution management methodology,
regional environment and health care policies.
The project partners implemented, harmonised and standardised PNC measurements in Augsburg and
Dresden (Germany), Prague (Czech Republic), Ljubljana (Slovenia) and Chernivtsi (Ukraine) and
investigated short-term effects of UFP on (cause-specific) mortality and hospital admissions in these
cities. The results are intended to make a knowledge based contribution to the environmental policy in
Europe (
Clean Air Plan
for Europe). It is worldwide one of the very few studies on short-term health
effects of UFP which is based on multicentre time-series meta-analyses. The lack of epidemiological
studies on UFP which follow this approach was clearly identified by the HEI report (2013) as one of
the critical data gaps from the epidemiological perspectives. Furthermore, most research activities on
UFP health effects were so far concentrated on Western European countries (or in USA).
For this study, measurements of PNC in different size ranges from 10 until 800 nm were conducted in
Dresden and Augsburg since 2011, since 2012 in Prague and Ljubljana, and since 2013 in Chernivtsi
(Figure 5). Due to the availability of mortality and hospital admission data as well as different start
points of UFP measurement, the statistical analyses of health effects were conducted for the following
periods: Dresden and Augsburg 2011-2012, Prague and Ljubljana 2012-2013 and Chernivtsi 2013.
Figure 5. Location of study areas and measurement sites.

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Handbook UFIREG Project
2
METHODS
Measurements
In the scope of UFIREG, PNC measurements were performed using custom-made mobility particle
size spectrometer, either Differential or Scanning Mobility Particle Sizer (DMPS/SMPS). They enable
highly size-resolved PNC measurements in the range from 10 to 800 nm (except in Prague: 10 to
500 nm) with total number concentrations from 100 to 100,000 particles per cm³. Regular maintenance
activities of the instruments and data processing as well as data validation were harmonised within the
project. Data processing (so-called inversion) of the electrical mobility distribution (measured by the
spectrometer) into the true particle number size distribution included the multiple charge correction
according to Pfeifer et al. (2014), coincidence correction of the condensation particle counter (CPC)
and the correction of the counting efficiency of the CPC. Particle losses due to diffusion in the inlet
system and the spectrometer were also quantified using theoretical functions in the data evaluation
software (Wiedensohler et al., 2012). The measurement principle and the data processing within
UFIREG are described in a simplified form in Figure 6.
For comparable measurements between the cities, small uncertainties in sizing and concentration are
required which can only be reached if the spectrometers are frequently quality assured. Therefore, an
extensive quality assurance programme was an essential part of UFIREG aiming at a high data quality.
It comprised staff training, an initial intercomparison of UFIREG spectrometers in a laboratory,
frequent on-site comparisons against reference instruments, remote monitoring, and automated
function control units at two sites.
Figure 6. From particles in the air to particle number concentrations within the database: Simplified
sketch of measurement principle and data processing within UFIREG (DMA: Differential Mobility
Analyser, CPC: Condensation particle counter)
All of the UFIREG measurement stations were located at an urban or suburban background site which
was representative for a large part of the urban population and had no roads with heavy traffic in
immediate vicinity. Most of the measurement stations were integrated in local air quality monitoring

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Handbook UFIREG Project
networks. At these sites, other air pollution parameters such as PM
10
, PM
2.5
, NO
x
, SO
2
, O
3,
and
partially black carbon as well as meteorological parameters were determined. The providers of the
different pollutant and meteorological data are shown in Table 1. Since there were different
regulations concerning air pollution and its monitoring in the Ukraine, only comparable PNC data
could be used from Chernivtsi.
Table 1. Sources of air pollutant data
Augsburg
1
Chernivtsi
Dresden
Ljubljana
2
Prague
PNC
Helmholtz Zentrum
München
L.I.Medved’s Research
Center of Preventive
Toxicology, Food and
Chemical Safety,
Ministry of Health,
Ukraine (State
enterprise)
Saxon State Office
for Environment,
Agriculture and
Geology
The National
Laboratory of
Health,
Environment and
Food
Institute of Chemical
Process
Fundamentals/
Czech
Hydrometeorological
Institute
PM/gas data
Bavarian
Environment
Agency
-
Saxon State Office
for Environment,
Agriculture and
Geology
Slovenian
Environment
Agency
Czech
Hydrometeorological
Institute
Meteorology
Bavarian
Environment
Agency
www.hmn.ru/index.php
?index=8&value=33658
Saxon State Office
for Environment,
Agriculture and
Geology
Slovenian
Environment
Agency
Czech
Hydrometeorological
Institute
EU station
code for the
official
monitoring site
DEBY007/
DEBY099
DESN092
SI0003A
CZ0ASUC
Analysis of air quality data
For the comparative analysis of the air quality situation at the five UFIREG sites, a two-year dataset
from May 2012 to April 2014 (Chernivtsi: January 2013 to April 2014) was considered.
The mobility particle size spectrometers operated within UFIREG deliver data in a 5 to 20 minute
time-resolution. In general, hourly and daily averages were calculated with a threshold of 75% data
availability. The overall availability of PNC data reached more than 75% at all stations (Table 2).
1
Air pollutants were measured at different urban background stations within the city (3-4 km distance).
2
Air pollutants were measured at different urban background stations within the city (600 m distance) until
November 2013.

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Table 2. Data availability of hourly PNC data in the UFIREG cities from May 2012 to April 2014
(Chernivtsi: January 2013 to April 2014)
Augsburg
Chernivtsi
Dresden
Ljubljana
Prague
90%
86%
88%
77%
82%
Regarding temporal and spatial variation, the statistical analyses and result visualisation were carried
out with the statistical open source project software R (R Core Team, 2014), and R package openair,
(Carslaw, Ropkins, 2012a) and (Carslaw, Ropkins, 2012b).
To investigate the influence of air mass origin on particle number size distribution patterns, a
meteorological cluster analysis based on back trajectories was performed
3
according to the trajectory-
clustering algorithm used before in Heintzenberg et al. (2011) which was principally based on the
approach of Dorling et al. (1992). 48 hours back trajectories were computed using HYSPLIT, a
trajectory model provided by the NOAA Air Resources Laboratory (Draxler, Hess, 2014) and radio
soundings were obtained from national meteorological stations.
The frequency of the new particle formation (NPF) events was assessed
4
using the method described
in Dal Maso et al. (2005). Daily plots of particle number size distributions and daily plots of the
positions of the modes of the multimodal distributions were considered. This method of the mode
position determination using mathematical gnostics is described in Ždímal et al. (2008). Every day
was classified into one of the category “event” (nucleation/new particle formation in other words),
“non-event”, “undefined”, or “missing”.
To define the impact of nucleation on the ultrafine particle number concentration, the nucleation
strength factor was determined which was first introduced by Salma et al. (2014). It was calculated as
the ratio of UFP and particles larger than 100 nm on nucleation days divided by the ratio of UFP and
particles larger than 100 nm on non-event days. Undefined days were disregarded for this calculation.
Epidemiological data
On the basis of air quality data generated through UFIREG measurements, the project team
investigated short-term effects of ambient air pollution on morbidity and mortality in the five cities
involved in the project. Deaths statistics and hospital admission statistics were used for information on
cause-specific morbidity and mortality.
Daily deaths and hospital admissions
Data on daily deaths and hospital admissions were collected for each of the five cities. Data on daily
deaths were collected for the residents of the city who died in the city. Data on daily hospital
admissions for each city were collected for the residents of the city who were hospitalised within the
city. Only ordinary (no day-hospital) and acute (no scheduled) hospitalisations were considered, since
the aim of the study was to investigate the association between daily pollutants concentrations and
acute adverse health outcomes.
3
In cooperation with Leibniz Institute for Tropospheric Research.
4
In cooperation with Institute of Chemical Process Fundamentals of the ASCR.

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Handbook UFIREG Project
The main diagnosis and cause of death, respectively, are based on the International Statistical
Classification of Diseases and Related Health Problems (ICD-10). Deaths due to natural causes, deaths
and hospital admissions due to cardiovascular and respiratory diseases were considered as primary
outcomes. A list of all outcomes is shown in Table 3.
The study periods for the two German cities Augsburg and Dresden were 2011 to 2012, for Prague and
Ljubljana 2012 to 2013 and for Chernivtsi 2013 only.
Table 3. Outcomes including ICD-10 codes.
ICD-10 code
Mortality
Hospital
admissions
Natural causes of death
A00 – R99
X
Diabetes
E10 – E14
X
Diseases of the circulatory system
I00 – I99
X
X
Cardiac diseases
I00 – I52
X
X
Ischaemic heart diseases
I00 – I25
X
X
Acute coronary events
I21 – I23
X
X
Arrhythmias
I46 – I49
X
X
Heart failure
I50
X
X
Cerebrovascular diseases
I60 – I69
X
X
Haemorrhagic stroke
I60, I61
X
Ischemic stroke
I63, I65, I66
X
Diseases of the respiratory system
J00 – J99
X
X
Lower respiratory tract infections
(LRTI)
J09 – J18
+ J20 – J22
X
X
Pneumonia
J12 – J18
X
Chronic
obstructive
pulmonary
disease (COPD)
J40 - J44 + J47
X
X
Asthma
J45 – J46
X
Confounder variables
We also collected information on other variables used for confounding adjustment. They include long-
term time-trend (date order), indicator variables for weekdays and holidays, meteorological parameters
(air temperature, relative humidity, barometric pressure) and – if available - influenza epidemics.
Table 4 shows the providers of data on mortality, hospital admissions and influenza epidemics.

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Table 4. Sources of health data.
City
Mortality data
Hospital admissions data
Information on influenza
epidemics
Augsburg
Research Data Centres of the
Federal Statistical Office +
Statistical
Offices
of
the
Länder
Research Data Centres of the
Federal Statistical Office +
Statistical
Offices
of
the
Länder
German Influenza Working
Group of the Robert Koch
Institute
Chernivtsi
Main Statistic Department in
Chernivtsi Region
Collected directly from the
hospitals
No data available
Dresden
Research Data Centres of the
Federal Statistical Office +
Statistical
Offices
of
the
Länder
Research Data Centres of the
Federal Statistical Office +
Statistical
Offices
of
the
Länder
German Influenza Working
Group of the Robert Koch
Institute
Ljubljana
National Institute of Public
Health
Statistical
Office
of
the
Republic of Slovenia
National Institute
of
Public
Health
Prague
Institute of Health Information
and Statistics of the Czech
Republic
Institute of Health Information
and Statistics of the Czech
Republic
National Institute of Public
Health + Hygiene Station of
the City of Prague
Sociodemographic data
Sociodemographic data such as number of inhabitants (per age-group and per sex), estimated
percentage of smokers, population density or number of newborns and deceased persons was used to
describe the population in the cities involved in the project.
Data for Augsburg derived from the statistical yearbook of Augsburg. For Dresden data were obtained
from the census in 2011 and the Statistical Office of the Free State of Saxony. The Statistical Office of
the Republic of Slovenia provided sociodemographic data for Ljubljana. Data for Prague were
obtained from the Institute of Health Information and Statistics of the Czech Republic and the Czech
Statistical Office. For Chernivtsi data derived from the Main Statistic Department in Chernivtsi
Region.
Epidemiological analysis
The association between air pollutants, and mortality or hospital admissions was investigated using
Poisson regression models allowing for overdispersion. In a first step, a basic confounder model was
set up a priori for all cities. This basic model included time-trend (date order), day of the week,
holidays, the decrease of the populations present in the city during vacation periods, influenza
epidemics (if available), air temperature, and relative humidity. In a second step air pollution effects
were estimated by each city. The city-specific estimates were pooled using meta-analyses methods.
We performed single-lag models from lag 0 (same day of the event) up to lag 5 (five days prior to the
event) to visually examine the lag structure of the association between particle exposures and health
outcomes. Cumulative effect models were used to represent immediate effects (lag 0-1), delayed
effects (lag 2-5) and prolonged effects (lag 0-5).
Cities were weighted according to the precision of the city-specific effect estimates. For pooling the

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Handbook UFIREG Project
city-specific estimates the maximum likelihood effects estimator after van Houwelingen was used (van
Houwelingen et al., 2002). We tested heterogeneity between the city-specific effect estimates using a
Chi-squared test and by quantifying the degree of heterogeneity with the index I
2
. An I
2
of 50%
indicates moderate heterogeneity and I
2
of at least 75% is an index for high heterogeneity between the
city-specific estimates.
3
RESULTS
Temporal and spatial variation of PNC in the UFIREG cities
The temporal variation of PNC was determined at one fixed monitoring site in each of the five project
cities. Overall, PNC and the temporal variation of different size fractions varied between the five sites.
Figure 7 shows the seasonal variation of PNC between 10 and 100 nm from May 2012 to April 2014.
The averaged PNC ranged from approximately 4,700 particles per cm
3
in Dresden in the winter
months (December to February) to 8,200 particles per cm
3
in Prague in the summer months (June to
August). In Prague and Dresden, there was a considerable influence of new particle formation due to
high global radiation and precursor gases in summer. Leaf burning in autumn is still common in
Chernivtsi and probably reflected by the high concentrations of particles shown in Figure 7 and 8. In
winter, thermal inversion may lead to high PNC which was in particular typical for Ljubljana (Figure
7 and 8).
Figure 7. Seasonal variation of particle number concentration (10-100 nm) in UFIREG cities from May
2012 to April 2014 (Chernivtsi: January 2013 – April 2014).

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Figure 8. Seasonal variation of particle number concentration (100-200 nm) in UFIREG cities from May
2012 to April 2014 (Chernivtsi: January 2013 – April 2014).
In comparison to the PNC, the lowest PM
10
concentrations during summer could be observed in
Dresden which can be explained with different sources for UFP and PM
10
and the negligible mass of
nucleation particles which mainly cause the high PNC in Dresden in summer. As for PNC the
variation between the cities was found to be smaller in spring but higher in winter. Due to inversion,
the highest PM
10
mass concentrations were also determined in Ljubljana in winter (Figure 9).
Unfortunately, PM
10
is not measured in Chernivtsi.
Figure 9. Seasonal variation of PM
10
in UFIREG cities from May 2012 to April 2014.
The season dependent weekly variation (Figure 10) shows the influence of different sources and
everyday life of the citizens living around the different UFIREG sites. In spring, the PNC are more or
less comparable during the working days at all UFIREG stations. At the weekends, PNC measured in
Ljubljana and Augsburg decreased due to less traffic. Although these two stations fulfil the criteria for

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urban background classification, there is a clear traffic impact. In Dresden and Chernivtsi, there seems
to be an active ”particle producing” weekend life on Saturdays in summer but the overall highest
averaged UFP concentrations could be observed in Chernivtsi on Saturdays in autumn. The increase in
UFP concentrations in Ljubljana on Friday especially in autumn and winter could not be explained yet
but was perhaps caused by commuters` traffic.
Figure 10. Weekly variation of particle number concentration (10-100 nm) in UFIREG cities from May
2012 to April 2014 (Chernivtsi: January 2013 – April 2014).
Figure 11. Diurnal weekly variation for particle number concentration (10-100 nm) for two sites in
Dresden in 2013; the urban background site is the UFIREG site; blue circle indicate maximum
concentration caused by the operation of a leaf blower directly beside the station in October 2013.

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The averaged diurnal variation for each weekday is exemplarily shown for two sites in Dresden for the
year 2013 in Figure 11. The UFP concentrations were about 1.5 times higher during the nights at the
traffic site than at the background site. During the traffic rush hours, the difference was even more
than twice as high. Moreover, the diurnal variation in Dresden showed differences between working
days and weekend at both sites. During the nights on Friday and Saturday, in particular observed in
summer, high concentrations were recorded probably due to barbecue and bonfires. In average, these
“nightlife peaks” were almost as high as the traffic peaks during weekdays. The maximum peak on
Wednesdays at the urban background station (marked with the blue circle) is caused by one single
event – a leaf blower operated closely to the station in October 2013 which led to PNC over 1 million.
To assess the spatial variation between the UFIREG sites, the coefficient of divergence (COD) and the
Spearman`s rank correlation was calculated with daily means of size-fractioned PNC. The size
dependency of the Spearman`s rank correlation coefficient can be seen in Figure 12. The results
indicate a strong relationship between PNC in Dresden and Prague and a slight to moderate
relationship between Dresden-Augsburg and Prague-Augsburg with an increasing correlation
coefficient for increasing particle sizes. For the PNC of all other UFIREG sites, almost no correlation
could be found.
Figure 12. Spearman rank correlation of daily averages of all UFIREG cities from May 2012 to April 2014
(Chernivtsi: January 2013 – April 2014).
The link between PNC and concentrations of basic pollutants such as NO
2
, NO, SO
2
, PM
10
and certain
meteorological parameters was also examined within UFIREG in order to indicate whether and how
the selected project stations are influenced by local sources and by different processes involved in the
creation and growth of individual modes of particles in the air. Table 5 shows the results of
Spearman`s rank correlation between daily means of PNC and other air pollutants.

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Handbook UFIREG Project
Table 5. Spearman`s rank correlation coefficient between daily means of size-fractioned particle number
concentrations and daily mean of PM
10
, NO, NO
2
and SO
2
from May 2012 to April 2014
5
.
10-20 nm
20-30 nm
30-50 nm
50-70 nm
70-100 nm
100-200 nm >200 nm
PM
10
Augsburg_LfU
6
0,17
0,20
0,28
0,44
0,60
0,73
0,87
Augsburg_BP
7
0,06
0,10
0,19
0,38
0,56
0,66
0,82
Dresden
-0,12
0,07
0,21
0,44
0,65
0,81
0,93
Ljubljana
-0,02
0,17
0,30
0,47
0,65
0,80
0,88
Prague
-0,28
-0,05
0,18
0,48
0,70
0,84
0,92
NO
2
Augsburg_LfU
0,59
0,65
0,73
0,77
0,80
0,79
0,53
Augsburg_BP
0,44
0,46
0,48
0,59
0,69
0,72
0,65
Dresden
0,08
0,21
0,22
0,33
0,46
0,55
0,64
Ljubljana
0,15
0,45
0,51
0,57
0,64
0,66
0,63
Prague
-0,16
0,07
0,17
0,42
0,64
0,74
0,77
NO
Augsburg_LfU
0,57
0,64
0,72
0,79
0,82
0,79
0,52
Augsburg_BP
0,44
0,44
0,44
0,51
0,57
0,56
0,56
Dresden
0,13
0,23
0,23
0,29
0,37
0,43
0,49
Ljubljana
0,21
0,52
0,63
0,71
0,75
0,71
0,59
Prague
-0,03
0,17
0,25
0,44
0,61
0,66
0,64
SO
2
Augsburg_LfU
0,15
0,15
0,17
0,22
0,26
0,28
0,25
Dresden
0,04
0,14
0,22
0,34
0,46
0,55
0,51
Ljubljana
-0,03
-0,02
-0,02
-0,01
0,04
0,10
0,12
Prague
-0,19
0,00
0,06
0,12
0,21
0,28
0,37
The correlation analyses indicate a different behaviour of the monitored stations. The stations in
Ljubljana and in Augsburg were apparently more affected by traffic primary particle emissions than in
Dresden and Prague as mentioned before. This was clearly reflected by correlation coefficients about
0.5 for correlation between the concentrations of the smallest particle fractions and nitrogen oxides in
Ljubljana and Augsburg. The high correlation between NO
x
and PNC in Augsburg is striking. The
gaseous pollutants in Augsburg were measured not at the same location as PNC. The monitoring site
at Bourges Platz is considered as urban background site and the measurement station at the premises
of Bavarian Environment Agency even as regional background site. The high correlations between the
traffic related air pollutants (PNC, NO, NO
2
) measured at different urban background sites suggest
that the single monitoring site operated in our study in Augsburg is representative for the entire city
area. In Augsburg the traffic is the major source of locally generated particles. For Prague and
Dresden, the correlation coefficient for this relation was smaller. At all stations, correlation analysis
shows growing relation between PNC and other pollutants with growing particle size except for SO
2
which is weakly correlated with PNC, especially in Ljubljana.
5
Graduation of the green colour from light to dark for a better visibility of correlation: coefficient R<0.2: no or
only very weak relationship (light green); 0.2<R<0.5: weak to moderate relationship; 0.5<R<0.8: clear
correlation; R>0.8: high or even perfect correlation (dark green).
6
LfU: Bavarian Environment Agency.
7
BP: Bourges Platz.

image
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image
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Handbook UFIREG Project
Another phenomenon which varied significantly between the UFIREG sites was new particle
formation (NPF), a process mostly driven by high global radiation under certain conditions such as the
concentration of precursor gases. The impact of NPF on PNC was assessed by calculating the
nucleation strength factor. According to Salma et al. (2014), a value of the nucleation strength factor
higher than two confirms NPF as the major source of UFP whereas a nucleation strength factor lower
than one means other emission sources may contribute considerably to the overall UFP concentration.
The daily cycle of the nucleation strength factor shown in Figure 13 emphasizes again the difference
between particle sources at the sites in Ljubljana and Augsburg in comparison to the other stations.
The contribution of NPF to the UFP concentration plays an important role in Dresden, Prague and
Chernivtsi.
Figure 13. Diurnal variations of nucleation strength factor (NSF) at the UFIREG sites; the horizontal line
at NSF value of 2 indicate when new particle formation influences PNC more than any other process.
Figure 14. Averaged particle number size distribution of all summer days classified as new particle
formation day; left: Ljubljana, right: Chernivtsi.

image
image
image
image
image
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Handbook UFIREG Project
Figure 15. Averaged particle number size distribution of all summer days classified as non-event day; left:
Ljubljana, right: Chernivtsi.
Figure 14 demonstrates the varying impact of NPF on the particle number size distribution in
Ljubljana as example for almost negligible new particle formation and Chernivtsi where considerably
more nucleation occurred resulting in a pronounced “nucleation banana”. On average, particles grew
up to about 50 to 60 nm in diameter on NPF days in all cities. Traffic influence can be seen at the
Ljubljana site on NPF as well as non-event days, whereas in Chernivtsi fewer particles could be
observed at the measurement site during the morning rush hour. However, high PNC in the evenings
were always clearly visible in Chernivtsi (Figure 15).
Besides global radiation, other meteorological conditions favour high PNC. Therefore, a
meteorological cluster analysis based on 48 hour back trajectories
was performed within UFIREG
which assessed the influence of air mass origin and thermal inversion or stability of stratification on
particle number size distribution. The Figures 16 and 17 show the results exemplarily for Prague. In
short, air masses coming from south and east, either warm (cluster 2 in red) or cold (cluster 1, 3, 4 in
black/grey, green and blue), were characterised by higher number concentrations of particles larger
than 100 nm if they reach Prague. In contrast, fast air masses from the west (cluster 7 in yellow) had
apparently fewer particles.
Figure 16. Left: Mean trajectories of nine air mass clusters coming to Prague; Right: Box plots of
temperature for the nine clusters.

image
image
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Handbook UFIREG Project
Figure 17. Box plots for particle number concentration in the range of 30-100 nm (left) and 100-200 nm
(right) for the nine clusters.
In summary, different sources for UFP could be identified. They included different combustion
processes such as from traffic, domestic heating, fireworks, bonfires, and leaf blowers. Also long-
range transport and new particle formation contribute to UFP levels in the ambient air. The in-depth
analysis of source apportionment for each site is still on-going and will provide important information
concerning strategies for the improvement of urban air quality.

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Handbook UFIREG Project
Descriptive statistics of health data
Table 6 shows a description of mortality outcomes by city for each year. In Augsburg, Dresden,
Ljubljana and Prague 40%-50% of natural death cases were due to cardiovascular diseases. In
Chernivtsi almost 70% of natural deaths were due to cardiovascular diseases in 2013.
Table 6. Description of (cause-specific) mortality outcomes by city.
City
Year
Population
Mean daily natural
death counts (SD)
Mean daily
cardiovascular
death counts (SD)
Mean daily
respiratory death
counts (SD)
Augsburg
2011
266 647
6.9 (2.5)
3.1 (1.7)
0.5 (0.8)
2012
272 699
7.2 (2.8)
3.1 (1.7)
0.4 (0.6)
Chernivtsi
2013
258 371
6.3 (2.7)
4.3 (2.1)
0.1 (0.4)
Dresden
2011
517 765
12.5 (3.6)
5.7 (2.4)
0.7 (0.9)
2012
525 105
13.1 (3.8)
5.8 (2.5)
0.7 (0.9)
Ljubljana
2012
280 607
5.8 (2.5)
2.3 (1.5)
0.4 (0.6)
2013
282 994
5.7 (2.4)
2.3 (1.5)
0.3 (0.5)
Prague
2012
1 246 780
27.1 (5.7)
13.7 (4.1)
1.5 (1.3)
2013
1 243 201
26.5 (5.9)
12.8 (3.8)
1.7 (1.4)
Outcome definitions: natural causes ICD-10 A00-R99, cardiovascular diseases ICD-10 I00-I99,
respiratory diseases ICD-10 J00-J99.
A description of hospital admissions by city for each year is shown in Table 7. So far, hospital
admission data is available for Augsburg (2011-2012), Chernivtsi (2013), Dresden (2011-2012),
Prague (2012-2013) and Ljubljana (2012). In all cities mean daily counts of cardiovascular hospital
admissions were higher than the mean daily counts of respiratory hospital admissions.

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Handbook UFIREG Project
Table 7. Description of cause-specific hospital admissions by city.
City
Year
Population
Mean daily
cardiovascular
hospital admissions
(SD)
Mean daily
respiratory hospital
admissions (SD)
Augsburg
2011
266 647
19.5 (8.5)
8.3 (3.9)
2012
272 699
19.7 (8.8)
8.6 (4.4)
Chernivtsi
2013
258 371
12.1 (5.7)
5.2 (3.3)
Dresden
2011
517 765
34.0 (12.6)
11.7 (4.7)
2012
525 105
34.3 (13.3)
11.5 (4.9)
Ljubljana
2012
280 607
14.4 (7.2)
8.2 (4.6)
Prague
2012
1 246 780
22.3 (8.7)
7.9 (4.0)
2013
1 243 201
24.3 (8.1)
9.8 (4.8)
Outcome definitions: cardiovascular diseases ICD-10 I00-I99, respiratory diseases ICD-10 J00-
J99.
Effects of ultrafine and fine particles on natural and cause-specific mortality
For the analysis of UFP health effects, only the size range 20 to 100 nm was used due to the relatively
high measurement uncertainty in the smaller size range 10 to 20 nm. Effects of UFP on mortality and
hospital admissions are presented as percent changes in relative risk in association with each 1,000
particles/cm
3
increase in daily UFP. Effects of PM
2.5
on mortality and hospital admissions are
presented as percent changes in relative risk in association with each 10 μg/m
3
increase in daily PM
2.5
.
The pooled relative risk of natural mortality increased by 0.36% (95%-confidence interval:[-0.27,
1.00]) in association with a 1,000 particles/cm
3
increase in daily UFP with a delay of one day (lag 1).
However, the association was not statistically significant and no increase in natural mortality in
association with an UFP increase could be found for other time lags.
Results on cardiovascular mortality were similar showing a delayed increase in the pooled relative risk
with an increase in daily UFP concentration. The strongest effect was found with a delay of three days
showing an increase in the risk of cardiovascular mortality by 0.33% [-0.57, 1.24] in association with
an increase of 1,000 particles/cm
3
in daily UFP. But overall, no significant increase in natural as well
as cardiovascular mortality could be observed in association with an increase in UFP.
Chernivtsi was excluded from the analysis on respiratory mortality due to insufficient respiratory
death cases in 2013. We observed an association between UFP and respiratory mortality across the
remaining four cities. An increase in daily UFP concentration was associated with a 2.13% [-0.43,
4.75] increase in the risk of respiratory mortality with a five days delay (Figure 18).

image
image
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Handbook UFIREG Project
Figure 18. Percent change in respiratory mortality associated with each 1,000 particles/cm
3
increase in
daily UFP (lag 5).
Chernivtsi was excluded in the analyses on PM
2.5
since PM
2.5
was not available there. Effects of PM
2.5
on mortality were heterogeneous. Augsburg showed a significant increase in the relative risk of natural
and cardiovascular mortality with increases in PM
2.5
with a delay of two to five days, whereas,
Dresden showed decreases in the relative risk of natural and cardiovascular mortality. Non-significant
but positive effect estimates were found for Prague and Ljubljana. Overall, the pooled effect estimates
indicated a delayed increase in cardiovascular mortality in association with a 10 μg/m
3
increase in
PM
2.5
(Figure 19), but no effect of PM
2.5
on natural mortality. All cities showed non-significant
associations between PM
2.5
and deaths due to respiratory diseases.
Figure 19. Percent change in cardiovascular mortality associated with each 10 μg/m
3
increase in daily
PM
2.5
(average of lag 2-5).
Weight (%) %-change [95%-CI]
Weight (%) %-change [95%-CI]

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Handbook UFIREG Project
Effects of ultrafine and fine particles on cause-specific hospital admissions
Non-significant associations between UFP and hospital admissions due to cardiovascular diseases
were found. But, we detected an increase in hospital admissions due to respiratory diseases in
association with an increase in UFP concentration. The pooled relative risk increased significantly
with an UFP increase in the 2-day average (1.44% [0.38, 2.53]) as well as with an UFP increase in the
6-day average (1.74% [0.35, 3.16]) (Figure 20).
Figure 20. Percent change in respiratory hospital admissions associated with each 1,000 particles/cm
3
increase in daily UFP (6-day average: lag 0-5).
We observed heterogeneous effects of PM
2.5
on cardiovascular hospital admissions. A 10 μg/m
3
increase in PM
2.5
was associated with an increase in the relative risk of cardiovascular hospital
admissions in Augsburg, Prague and Ljubljana. However, Dresden showed non-significant decreases
in cardiovascular hospital admissions in association with an increase in PM
2.5
(Figure 21).
Figure 21. Percent change in cardiovascular hospital admissions associated with each 10 μg/m
3
increase in
daily PM
2.5
(lag 5).
Weight (%) %-change [95%-CI]
Weight (%) %-change [95%-CI]

image
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Handbook UFIREG Project
The association between PM
2.5
and hospital admissions due to respiratory diseases was significant. The
pooled relative risk of respiratory hospital admissions increased with a delay of one (3.06% [1.55,
4.60]) to five days (2.29% [0.60, 4.00]) as well as with an increase in the 6-day average of PM
2.5
(5.15% [3.00, 7.33]) (Figure 22).
Figure 22. Percent change in respiratory hospital admissions associated with each 10 μg/m
3
increase in
daily PM
2.5
(6-day average: lag 0-5).
4
DISCUSSION AND CONCLUSIONS
Quality assured measurements of UFP or of highly size-resolved PNC is still a challenge. However,
within UFIREG the measuring routine could be improved considerably. Although an extensive quality
assurance (QA) programme was performed within the scope of UFIREG, it emerged throughout the
project that QA should be even more emphasised in future projects. To this end, important knowledge
about future QA measures could be gained within UFIREG. The uncertainty of UFP/PNC
measurements is still about +/- 20% due to the measurement principle in general and to the relatively
new measurement technique and is, therewith, higher than for other air pollutants. Consequently, the
instrument`s quality and the measurement uncertainty need to be monitored and checked by reference
instruments on-site on a very regular basis, especially with regard to epidemiological studies.
The complex QA, the high investment and running costs and the lack of legal regulations cause the
sluggish integration of UFP/PNC measurements in official monitoring networks. In consequence, the
data basis for epidemiological analyses is poor and epidemiological evidence for health effects of UFP
is still not conclusive.
Determination of the total PNC by particle counters could be an alternative for the elaborate size-
resolved PNC measurements. However, only particle number size distribution data enable in-depth
analysis, especially for identifying particle sources. These data are also more suitable for
epidemiological studies such as in UFIREG.
Weight (%) %-change [95%-CI]

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Handbook UFIREG Project
Following the comparative air quality analysis at the UFIREG sites, it revealed that PNC depends
more on the special location of the measurement station (distance to the road, surrounding houses,
traffic intensity, distance to the city centre, dominant wind direction) than it is the case for PM
10
and
PM
2.5.
That should be considered if choosing the appropriate site for PNC measurements, especially
for long-term epidemiological studies.
In summary, the results demonstrate that PNC in urban areas depend strongly on different factors such
as the activity of different sources whereby the everyday life of people plays an important role,
meteorological conditions, cityscape as well as orographic situation. The sources include different
combustion processes such as from domestic heating, traffic, fireworks, bonfires or leaf blowers.
Hence, a reduction of PNC is possible through less traffic, lower-emission vehicles, better air
circulation in cities, less biomass burning (autumn and winter) and less bonfires/barbecues (summer).
The results of the epidemiological analyses indicate delayed effects of UFP on respiratory mortality as
well as immediate and prolonged effects of UFP on respiratory hospital admissions. Moreover, results
showed a significant association between PM
2.5
and respiratory hospital admissions. The effects of
PM
2.5
on natural and cardiovascular mortality as well as cardiovascular hospital admissions were
heterogeneous.
Further analyses regarding two-pollutant models and effect modification by several factors such as
age, sex, season, wind direction and new particle formation are ongoing in order to find an explanation
for the heterogeneity between the cities. Moreover, sensitivity analyses on the confounder models will
be conducted to test the robustness of the results.
Due to different starting points of UFP measurements and because of delayed availability of health
data in Germany it was not possible to use the same analysing periods for all five cities. Moreover, for
Chernivtsi only one year could be investigated due to limited data availability. Differences in coding,
difficulties in the exclusion of scheduled hospital admissions as well as in the restriction to people
living in the city and hospitalised in the city might cause differences between the cities with regard to
hospital admissions. However, UFIREG was one of the first multi-centre study investigating the
effects of UFP on (cause-specific) mortality and hospital admissions including cities from Central and
Eastern European countries since most research activities were so far concentrated on Western
European countries. Moreover, it was the first study on UFP using harmonised UFP-measurements in
all the five cities.
It is still not possible to draw definite conclusions on exposure to UFP and adverse health effects
despite a growing scientific literature. Further multi-centre studies such as UFIREG are needed
preferably investigating several years in order to produce powerful results. There are still few
epidemiological studies investigating adverse health effects of UFP. Therefore, it is important to
integrate UFP into routine measurement networks in order to provide data for short- as well as long-
term epidemiological studies.
5
RECOMMENDATIONS
So far no directives for regulation of UFP in ambient air and almost no official measurement sites
which routinely measure UFP exist. Usually, research results are used to formulate recommendations
and guidelines, e.g. the WHO Air Quality Guidelines (WHO, 2005), which support policymakers in
setting thresholds of air pollution constituents for national and European policy on air quality control

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Handbook UFIREG Project
such as the EU Air Quality Directive
8
. At this stage, further research is required to draw definite
conclusions on exposure to UFP and adverse health effects. Policymakers and stakeholders in turn can
support routine measurements of UFP and research efforts at his stage.
Research
The UFIREG project and other scientific studies have uncovered a number of knowledge gaps: there is
still (a) limited epidemiological evidence on the effect of short-term exposure to UFP on health; (b)
insufficient understanding of whether the effects of UFP are independent of those of PM
2.5
and PM
10
;
(c) no evidence on the effects of long-term exposure to UFP on health, and (d) little evidence showing
which size ranges or chemical characteristics of UFP are most significant to health (WHO Regional
Office for Europe, 2013).
Larger and more specific multi-centre studies and long study periods are needed to produce powerful
results. The creation of so-called supersites or special sites should be considered (WHO Regional
Office for Europe, 2013). Concentration–response functions need to be established for UFP and for
newly identified health outcomes. This will also require the generation of large data sets on these
exposure metrics (WHO Regional Office for Europe, 2013).
The project consortium is suggesting further pursuing open research questions (Box 2).
Box 2. Identified further research questions
-
Are the short-term health effects of UFP comparable in cities across Europe? (More
multicentre time-series studies including meta-analysis are needed.)
-
What are the health effects of personal short-term exposures to UFP?
-
What are the health effects of pollutant mixtures and together with individual activities i.e. in a
tunnel or during physical activity?
-
Are the health effects of UFP independent of the health effects of black carbon and/or other
criteria air pollutants?
-
What are the long-term health effects of UFP and their components?
-
Are population groups spending more time near traffic more at risk compared to other groups?
-
How effective are measures implemented for increasing air quality in urban settings?
-
Which are the main sources of UFP and how to estimate the health effect impact of specific
UFP sources?
Policymakers and stakeholders
As mentioned before, current data and studies on the levels of UFP and their health effects do not
allow firm conclusions on exposure limits and respective health effects to be considered in European
air quality guidelines. On the other hand, to date, UFP are not included in routine measurements of air
quality monitoring stations. This in turn explains the lack of data for epidemiological studies. At this
8
Directive 2008/50/EC of the European Parliament and of the Council of 21 May 2008 on ambient air quality
and cleaner air for Europe.

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Handbook UFIREG Project
stage, policymakers and stakeholders are called upon for supporting routine measurements and
research efforts to resolve this chicken-egg situation through:
Continuing efforts to integrate UFP into routine measurement networks in order to provide
data for short- as well as long-term epidemiological studies:
Supporting multi-pollutant approaches, as so far pollutants are most often assessed
independently.
Fostering the conduct of epidemiological studies to assess the association between UFP levels
and adverse health effects;
Facilitating studies for evidence that may allow defining limit values for daily concentrations
of UFP.
Developing and implementing measures to reduce UFP emissions, particularly from transport
and domestic heating/biomass burning. Measures may include:
Encouraging mass public transit and alternative energy sources for vehicles
(electric and hybrid technologies);
Encouraging fewer road traffic journeys and more physically active transport;
Supporting concept of low emission zones (incl. shipping traffic in cities);
Supporting urban planning measures that help control hot spots such as near
road microenvironments;
Supporting reliable filter systems for heavy duty vehicles (construction
machinery), ships and heating systems.
Helping protect people from UFP and soot particles also at occupational sites (e.g.
construction sites).
Strengthening communication and awareness raising for professionals and the public in
relation to air pollution and particulate matter, including UFP.
High costs and lack of regulations could however hamper efforts to integrate UFP into routine
measurements (Box 3).
Box 3. How much does UFP monitoring cost? (UFIREG, 2014)
Costs of particle number concentration measurements are composed of non-recurring investment
costs, running costs (consumables, chemicals, electricity etc.), personnel costs and extraordinary
costs. Investment and running costs have been estimated to be relatively high, on the basis of the
UFIREG experience. High costs and lack of regulations prevent many institutions and authorities
from including these measurements in the monitoring programmes of cities, regions or countries.
UFIREG suggests re-evaluating future requirements and challenges of air quality control.
Instruments to measure the distribution of particles sizes are expensive in investment and running
costs and can only be introduced at special sites (supersites).
So far, no directives for the regulation of UFP in ambient air and almost no official measurement sites
which routinely measure UFP exist. Even if further research is required to formulate guidelines or set
threshold, policymakers and stakeholders can support the process at this stage.

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Handbook UFIREG Project
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(available
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http://www.euro.who.int/__data/assets/pdf_file/0004/193108/REVIHAAP-Final-technical-report-
final-version.pdf; accessed 22 October 2014).
WHO (2005): Air quality guidelines, global update 2005. Geneva, Switzerland (available at:

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Handbook UFIREG Project
http://www.euro.who.int/__data/assets/pdf_file/0005/78638/E90038.pdf?ua=1;
accessed
23
October 2014).
Wiedensohler A, Birmili W, Nowak A (2012): Particle mobility size spectrometers: harmonization of
technical standards and data structure to facilitate high quality long-term observations of
atmospheric particle number size distributions, Atmos. Meas. Tech., 5, 657–685.
Ždímal V, Brabec M, Wagner Z (2008): Comparison of Two Approaches to Modeling Atmospheric
Aerosol Particle Size Distributions. Aerosol and Air Quality Research, 8(4), 392–410.

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Handbook UFIREG Project
FIGURES
Figure 1. Size comparisons of particulate matter .................................................................................... 6
Figure 2. Regional deposition of particles in the human respiratory tract .............................................. 6
Figure 3. Organs of the human body that can be affected by air pollution ............................................. 7
Figure 4. Stages in life of special susceptibility toward air pollution ..................................................... 7
Figure 5. Location of study areas and measurement sites....................................................................... 9
Figure 6. Simplified sketch of measurement principle and data processing within UFIREG ............... 10
Figure 7. Seasonal variation of particle number concentration (10-100 nm) in UFIREG cities ........... 15
Figure 8. Seasonal variation of particle number concentration (100-200 nm) in UFIREG cities ......... 16
Figure 9. Seasonal variation of PM
10
in UFIREG cities........................................................................ 16
Figure 10. Weekly variation of particle number concentration (10-100 nm) in UFIREG cities ........... 17
Figure 11. Diurnal weekly variation for particle number concentration (10-100 nm) for two sites in
Dresden in 2013. ................................................................................................................................... 17
Figure 12. Spearman rank correlation of daily averages of all UFIREG cities ..................................... 18
Figure 13. Diurnal variations of nucleation strength factor (NSF) at the UFIREG sites ...................... 20
Figure 14. Averaged particle number size distribution of all summer days classified as new particle
formation day ........................................................................................................................................ 20
Figure 15. Averaged particle number size distribution of all summer days classified as non-event day
............................................................................................................................................................... 21
Figure 16. Left: Mean trajectories of nine air mass clusters coming to Prague .................................... 21
Figure 17. Box plots for particle number concentration in the range of 30-100 nm (left) and
100-200 nm (right) for the nine clusters. ............................................................................................... 22
Figure 18. Percent change in respiratory mortality associated with UFP ............................................. 25
Figure 19. Percent change in cardiovascular mortality associated with PM
2.5
...................................... 25
Figure 20. Percent change in respiratory hospital admissions associated with UFP ............................. 26
Figure 21. Percent change in cardiovascular hospital admissions associated with PM
2.5
..................... 26
Figure 22. Percent change in respiratory hospital admissions associated with PM
2.5
........................... 27

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Handbook UFIREG Project
TABLES
Table 1. Sources of air pollutant data .................................................................................................... 11
Table 2. Data availability of hourly PNC data in the UFIREG cities ................................................... 12
Table 3. Outcomes including ICD-10 codes. ........................................................................................ 13
Table 4. Sources of health data. ............................................................................................................ 14
Table 5. Spearman`s rank correlation coefficient between daily means of size-fractioned particle
number concentrations and daily mean of PM
10
, NO, NO
2
and SO
2
..................................................... 19
Table 6. Description of (cause-specific) mortality outcomes by city.................................................... 23
Table 7. Description of cause-specific hospital admissions by city...................................................... 24
BOXES
Box 1. Ultrafine Particles ........................................................................................................................ 8
Box 2. Identified further research questions .......................................................................................... 29
Box 3. How much does UFP monitoring cost?......................................................................................30

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Handbook UFIREG Project
ULTRAFINE PARTICLES – AN EVIDENCE BASED CONTRIBUTION TO THE
DEVELOPMENT OF REGIONAL AND EUROPEAN ENVIRONMENTAL AND
HEALTH POLICY (UFIREG)
INTERREG IV B CENTRAL EUROPE
Project number
: 3CE288P3
Duration:
7/2011 – 12/2014
Website:
www.ufireg-central.eu
Project Partners
Technische Universität Dresden, Research Association Public Health Saxony
(Lead Partner)
Fetscherstr. 74, D-01307 Dresden
Dr. Anja Zscheppang | Dr. Monika Senghaas
anja.zscheppang@tu-dresden.de | monika.senghaas@tu-dresden.de
Saxon State Office for Environment, Agriculture and Geology
Pillnitzer Platz 3, D-01326 Dresden
Dr. Gunter Löschau | Dr. Susanne Bastian
gunter.loeschau@smul.sachsen.de | susanne.bastian@smul.sachsen.de
Helmholtz-Zentrum München – German Research Center for Environmental Health
Institute of Epidemiology II
Ingolstädter Landstr. 1, D-85764 Neuherberg
Dr. Josef Cyrys | Dr. Alexandra Schneider
cyrys@helmholtz-muenchen.de
| alexandra.schneider@helmholtz-muenchen.de
Institute of Experimental Medicine, Academy of Sciences of the Czech Republic
Vídeňská 1083, CZ-142 20 Prague
Dr. Miroslav Dostál
dostal@biomed.cas.cz
Czech Hydrometeorological Institute
Na
Šabatce
2050/7, CZ-143 06 Prague
Jiří Novák
novakj@chmi.cz
The National Laboratory of Health, Environment and Food
Prvomajska ulica 1, SI-2000 Maribor
Matevz Gobec
matevz.gobec@nlzoh.si
L.I. Medved’s Research Center of Preventive Toxicology, Food and Chemical Safety, Ministry of Health,
Ukraine (State enterprise)
Heroiv oborony str. 6, UA-03680 Kiev
Prof. Dr. Dr. Leonid Vlasyk
leonid_vlasyk@mail.ru

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Technische Universität Dresden
Research Association Public Health Saxony
Dresden, Germany
www.tu-dresden.de
Saxon State Office for Environment,
Agriculture and Geology
Dresden, Germany
www.smul.sachsen.de/lfulg
Helmholtz Zentrum München – German
Research Center for Environmental Health
(GmbH)
Neuherberg, Germany
www.helmholtz-muenchen.de
Institute of Experimental Medicine,
Academy of Sciences of the Czech Republic
Prague, Czech Republic
www.iem.cas.cz
Czech Hydrometeorological Institute
Prague, Czech Republic
www.chmi.cz
National Laboratory of Health, Environment
and Food
Maribor, Slovenia
www.nlzoh.si
L.I. Medved´s Research Center of Preventive
Toxicology, Food and Chemical Safety,
Ministry of Health, Ukraine (State enterprise)
Kiev, Ukraine
www.medved.kiev.ua
UFIREG is implemented through the CENTRAL EUROPE Programme co-financed by the ERDF