N. Kranjec, A. Galičič, I. Eržen et al. • The impact of ultrafine particles on daily counts of deaths from respiratory diseases in the Municipality... Nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3), carbon monoxide (CO), heavy metals, volatile organic compounds and pesticides one of the most common outdoor air pollutants in Slovenia and in Europe. InTroducTIon Particulate matter is besides nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3), carbon monoxide (CO), heavy metals, volatile organ­ic compounds and pesticides one of the most common outdoor air pol­lutants in Slovenia and in Europe [1, 2]. The division of particulate matter is most commonly based on aerodynamic diameter, including particles with aerodynamic diameter less than 10 µm (PM10), less than 2.5 µm (PM2.5), less than 1 µm (PM1), and less than 0.1 µm (PM0.1), with the last group also labeled as ultrafine particles (UFPs). Taken from the report Air quality in Slovenia 2014 [1], the main source of PM (62 %) and PM(74 %) are small furnaces. 102.5 UFPs are particles of outdoor air pollution, with aerodynamic diameter less than 0.1 µm. Chemical compounds and physical shape of UFPs is dependent on the source of formation and secondary formations in out­door air. Primary UFPs are formed directly at the emission source, whereas secondary UFPs are formed as a homogenous nucleation of gases [3-5]. The distribution and the type of UFPs are strongly de­pendent on the type of diesel exhaust, as traffic is counted as one of the main UFPs formation sources [6, 7]. Sources of emission of UFPs are also small furnaces, biomass boilers, and emissions from industrial coal fueled power plants [8-10]. Concentrations of ultrafine particle (UFP) number concentrations in the environment, where there are no anthropogenic sources of formation, vary between few to twenty thou­sand particles on cm3 [10]. Even though UFPs have high particle number concentrations on cm3, they add very little to total mass of particles of different sizes (total mass concentration of particles of vari­ous sizes) [11]. Variation of UFP number concentration is dependent on location and seasonal and daily temporal variability of meteorologi­cal and ecological parameters [4]. The formation of UFPs is also strongly associated with pollutants, which are formed in combustion processes, like nitrogen oxides (NOx) and carbon monoxide (CO) [12]. One of the most important UFP characteristics, influencing public health, is chemical properties of particles, mostly elemental composi­tion, inorganic ions and carbonaceous compounds [5, 13]. Considering bigger relative surface area of UFPs in comparison to coarse particles, it is predicted that UFPs have bigger toxicological effect on health; small particle size diameter is enabling them to enter into the blood­stream and thus spread in the whole organism through penetration into the lung tissue compartments [5, 11]. UFP deposition in the respiratory tract can be affected by physical activity, entryway – oral versus nasal breathing, disease status, and individuals age [9]. UFP deposition importantly affects the development of respiratory and cardiovascular diseases and functioning of other internal organs [11]. Exposure to total deposited fraction of UFPs is higher in asthmatic than in non-asthmatic children [14]. Health risk is also associated with heightened immune response, which may lead to the formation of blood clots and can cause myocardial infarction and stroke [10]. Heightened risks of sudden asthma exacerbation, induced allergy response, throm­ © Inštitut za sanitarno inženirstvo, 2016 The impact of ultrafine particles on daily counts of deaths from respiratory diseases in the Municipality... • N. Kranjec, A. Galičič, I. Eržen et al. bosis, and endothelial dysfunction have also been confirmed [9, 15]. In patients with asthma, exposure to UFPs has a more significant effect on exacerbation of acute respiratory diseases [16]. Exposure to UFPs in outdoor air can reduce vascular reactivity and can significantly reduce venous nitrate (NO) concentrations [17]. The impact of the delayed and cumulative effects of UFPs pollution has also been discussed. Cumula­tive effects of 5-day UFPs pollution levels are stronger than health ef­fects which appear right after the exposure [17]. Exposure to UFPs is associated with the decrease of electrical activity of the heart, which may lead to myocardial infarction [18, 19]. Exposure to UFPs exerts proinflammatory effects through oxidative stress response, and with the formation of reactive oxygen spices (ROS) stimulates the progression of atherosclerosis and precipitation of acute cardiovascular response, which involves all responses from the increased blood pressure to myocardial infarction [20]. Besides the effect on the development of respiratory dis­eases and cardiovascular system, UFPs have other effects on human health. Exposure to UFPs increases the levels of biomarkers for neu­trophilic inflammation [21]. In patients with chronic respiratory diseas­es, exposure to UFPs can induce immune response of the white blood cells (monocytes) [22]. UFPs can change the structure of DNA [23]. Contradictory effects of UFPs partly come from the increased oxidative stress in the tissue and their subsequent impairment of the phagocytic Traffic is counted as one of ability of alveolar macrophages and phagocyte activity [20, 24]. the main UFPs formation Confirmation for the association between exposure to UFPs and other sources. Sources of emission acute health outcomes (such as mortality and dysfunction of the central of UFPs are also small nervous system) and chronic health outcomes (mortality and respiratory furnaces, biomass boilers, system dysfunction, reproductive and developmental effects, cancer, gen­ and emissions from industrial otoxicity and mutagenicity) were conducted as inconsistent [19, 25–28]. coal fueled power plants. Epidemiological studies at the population level, because of inconsisten­cies in their conclusions, still cannot firmly ascertain the association be­tween exposure to UFPs in outdoor air and morbidity and mortality for either cardiovascular or respiratory diseases [9–11]. Lanki et al. [19] have confirmed positive and statistically significant temporal variable as­sociation between UFP number concentrations in outdoor air and daily number of hospital admissions because of acute myocardial infarction. Positive and statistically significant temporal variable association was proven between UFP number concentration in outdoor air and number of daily hospital admissions and daily counts of deaths because of stroke; UFP number concentrations in warmer seasons have been prov­en by Kettunen et al. as well [29]. Leitte et al. [16] have proven positive and statistically significant temporal variable association between daily number of emergency room visits for respiratory diseases and UFP size fraction between 0.05 in 0.10 µm. This association has not been proven for UFP size fraction smaller than 0.05 µm. Spirometric lung function was found to be non-significantly associated with concentrations of ul­trafine particle (UFP) number concentrations [28, 30]. The aim of this study is to assess the temporal variable association be­tween UFP number concentrations in outdoor air and daily counts of deaths from respiratory diseases in the Municipality of Ljubljana (MOL). International Journal of Sanitary Engineering Research Vol. 10 . No. 1/2016 N. Kranjec, A. Galičič, I. Eržen et al. • The impact of ultrafine particles on daily counts of deaths from respiratory diseases in the Municipality... MeTodoLoGY Study type and observed population For the observation of association between UFPs and daily counts of deaths from respiratory diseases in MOL, an epidemiological ecological temporal variability study was implemented. The unit of observation was represented as a single day in the period between January 1st, 2012 and December 31st, 2013. In total, there were 731 days of ob­servation in this period. The observed population was represented by residents of MOL aged 1 year or older, who died of respiratory diseases in the period of observation. Area of observation An area of observation in our study is an administrative unit of the Mu­nicipality of Ljubljana. In the first year (2012), MOL consisted of 280,278 residents; in the second year (2013) MOL consisted of 282,741 residents. Population density in 2012 counted as 1,019.2 m2 and in 2013 as 1,028.1 m2 [31]. MOL is situated in a basin, for which winter temperature inversion is characteristic, which causes long-term fog. Temperature inversion also creates poor airing of the basin, which further causes decreased dilu­tion of pollutants. In the year 2013 in MOL, 17 industrial sources were presented, which yearly produce over 100 kg of total dust from com­bustion sources. The total dust mass of 17 industrial sources in MOL in 2013 was 62,096 kg [32]. data collection Health and environmental data for this temporal variability study was collected within the European project UFIREG (Ultrafine particles – co­operation with environmental and health policy). UFIREG project start­ed in July 2011 and finished in December 2014 in four European countries – Dresden and Augsburg (Germany), Prague (Czech Repub­lic), Ljubljana (Slovenia) and Chernivtsi (Ukraine) [33]. Daily counts of deaths from respiratory diseases Health data was collected from death register, kept by the National In­stitute of Public Health. In the study, daily counts of deaths from respi­ratory diseases (ICD-10 (The International Statistical Classification of Diseases and Related Health Problems, 10th Revision), code J00 – J99) were recorded [34]. From the death register, the date of death, diagnosis of deaths, age at death, and gender were collected. Ultrafine particles in outdoor air UFP number concentrations were measured depending on the size (angl. Particle Number Concentration – PNC) in the time interval from 5 to 20 minutes, which were calculated to daily average concentra­tions. 24-hr average UFP number concentrations were calculated for five size ranges: UFP size from 0.01 to 0.02 µm, from 0.02 to 0.03 µm, from 0.03 to 0.05 µm, from 0.05 to 0.07 µm and from 0.07 to 0.10 µm as particle number/cm3. © Inštitut za sanitarno inženirstvo, 2016 The impact of ultrafine particles on daily counts of deaths from respiratory diseases in the Municipality... • N. Kranjec, A. Galičič, I. Eržen et al. UFP number concentration was collected on measuring sites, on the location at The National Institute of Chemistry, Hajdrihovaulica 19, Ljubljana. Kindergarten, primary school and multistorey buildings are situated in the vicinity of the measuring site. Measuring site is situated 50 m from the nearest road. In the vicinity of the measuring site, the railway station is situated (approximately 1 km). The measuring site is situated in the urban environment, and measurements are representa­tive for MOL [33]. Statistical analysis Distribution and temporal variability of daily counts of deaths from res­piratory diseases and daily UFP number concentrations in outdoor air are represented in tabular form with statisticaly significant parameters: mean, standard deviation, minimum and maximum value, quartile 1, median, quartile 3, total number of observed days, and total number of missing data. Temporal variability of daily counts of deaths from respiratory diseases and UFP number concentrations for each particle size diameter is displayed with sequence diagrams. For description of the observed variables and temporal variability, a statistical programme SPSS version 21.0 (SPSS Inc., Chicago, IL, ZDA) was used. reSuLTS data description Daily counts of deaths from respiratory diseases Daily counts of deaths from respiratory diseases were collected for 731/731 (100 %) observed days. Statistically significant values for data variability of daily counts of deaths from respiratory diseases for the years 2012 and 2013 are displayed in Table 1. Ultrafine particles in outdoor air Data for individual UFP size ranges (UFP, UFP, UFP, 0.01-0.020.02-0.030.03-0.05 UFPand UFP) was in the observed period measured for 0.05-0.07 0.07-0.10 435/731 (59,5 %) days. In total,this presents 296 (40,5 %) missing entries of UFP number concentration measurements. The chosen typi­cal statistical values for distribution of average 24-hr UFP number con­centrations for individual UFPs size ranges are displayed in Table 2. Table 1: Distribution of statistical values data for daily counts of deaths from respiratory diseases in the Municipality of Ljubljana in years 2012 and 2013 Year Mean Sd Min. Q1 Median Q3 Max. n Md 2012 0.37 0.64 0 0.00 0.00 1.00 3 366 0 2013 0.31 0.52 0 0.00 0.00 1.00 2 365 0 Legend: SD – standard deviation; Q1 – quartil 1;Q3– quartil 3; N – total number of oberved days; MD– number of missing data International Journal of Sanitary Engineering Research Vol. 10 . No. 1/2016 N. Kranjec, A. Galičič, I. Eržen et al. • The impact of ultrafine particles on daily counts of deaths from respiratory diseases in the Municipality... Table 2: Distribution of chosen typical values of average 24-hr number concentrations of UFP, UFP, UFP, 0.01-0.020.02-0.030.03-0.05 UFPand UFPin the Municipality of Ljubljana in years 2012 and 2013 0.05-0.07 0.07-0.10 Size ranges of uFPs Year Average Sd Min. Q1 Median Q3 Max. n Md UFD0.01-0.02 2012 1549.84 503.63 361 1200.28 1499.37 1903.08 3203 147 219 2013 1303.19 518.48 29 939.32 1222.0 1584.80 3564 288 77 UFD0.02-0.03 2012 1203.00 405.15 190 907.47 1158.59 1433.03 2462 147 219 2013 1113.33 433.37 92 838.40 1063.84 1346.27 3360 288 77 UFD0.03-0.05 2012 1571.23 571.64 183 1150.06 1537.13 1887.38 3897 147 219 2013 1483.22 628.58 267 1102.01 1392.05 1752.15 4164 288 77 UFD0.05-0.07 2012 1029.51 418.72 191 763.63 939.05 1226.13 3127 147 219 2013 994.42 472.69 232 659.13 897.34 1189.20 3447 288 77 UFD0.07-0.10 2012 1032.09 488.27 292 743.18 924.83 1188.02 3610 147 219 2013 1029.71 575.63 281 683.59 886.20 1195.85 4208 288 77 Legend: SD – standard deviation; Q1 Figure 1: Temporal variability: a) daily counts of deaths from respiratory diseases, – quartil 1;Q3– quartil 3; N – total number of data; MD – number of missing data Temporal variability of health and environmental data Temporal variability of daily counts of deaths from respiratory diseases of MOL population and UFP number concentration in outdoor air for each UFP size range in the years 2012 and 2013 is displayed with sequence diagrams in Figure 1. b) average 24-hour number concen­tration of UFP(number/cm3), 0.01-0.02 c) average 24-hour number concentra­tion of UFP(number/cm3), 0.02-0.03 d) average 24-hour number concen­tration of UFP(number/cm3), 0.03-0.05 e) average 24-hour number concen­tration of UFP(number/cm3) and 0.05-0.07 f) average 24-hour number concentra­tion of UFP(number/cm3) in the 0.07-0.10 Municipality of Ljubljana in years 2012 and 2013. © Inštitut za sanitarno inženirstvo, 2016 The impact of ultrafine particles on daily counts of deaths from respiratory diseases in the Municipality... • N. Kranjec, A. Galičič, I. Eržen et al. dIScuSSIon daily counts of deaths from respiratory diseases Collection of health data did not present any difficulties. Data of daily counts of deaths from respiratory diseases in MOL population was col­ lected for all days within the observed period from January the 1st , 2012 to December 31st, 2013. The highest daily counts of deaths from respiratory diseases in 2012 were in the period between the middle of February and the middle of April and again from the beginning of May to the middle of July and in October. Daily counts of deaths from respiratory diseases increased again from December 2012 to April 2013. In the year 2013, daily counts of deaths were again higher from the middle of May to the mid­ dle of July and in October. High daily counts of deaths in the years 2012 and 2013 coincide with the period of flu epidemic, which was in 2012 between the 4th and 14th week [35] and between the 2nd and 14th week in the year 2013 [36]. The highest daily counts of deaths from respiratory diseases were three deaths per day. The period with the highest daily counts of deaths from respiratory diseases in the year 2012 started at the beginning of Feb­ ruary and continued to the beginning of April and repeated again in the first half of July. In the year of 2013, the highest daily counts of deaths from respiratory diseases (three deaths per day) did not repeat. The highest daily counts of Daily counts of deaths from respiratory diseases show a repetitive pat- deaths from respiratory tern, which is typically seasonal. Seasonal predisposition is proven in diseases were three deaths the association with the number of emergency room visits [16] and per day. mortality for myocardial infarction [29, 37]. Leitte et al. [16] report exacerbation of health conditions on weekends and holidays. ultrafine particles in outdoor air Concentration of UFPs was slightly hightened in December and January, which is followed with a slight decrease of concentration in spring and in summer. Slight winter increase of UFP number concentrations can pro­ bably be associated with combustion in small furnaces in households. Even though seasonal temporal variability of UFP number concentrations in outdoor air is recognisable, there are still only slight differences in UFP number concentrations in outdoor air. This confirms that UFP number concentrations are mostly conditioned by traffic emissions, because 90 % of the secondary UFP formation in outdoor air is associated with the combustion of dieasel exhaust [7, 38]. In risk management of heightened UFP concentrations and consequently their health effect, it is important to have in mind that environmental indicator in Slovenia “The extent and structure of public transport and traffic” shows that growth of motorized traffic is above the average in comparison to EU [39]. Temporal variability of daily counts of deaths from respiratory diseases and uFP outdoor air pollution The length of the observed period was conditioned by the European project UFIREG. A 2-year observational period of health and UFP International Journal of Sanitary Engineering Research Vol. 10 . No. 1/2016 41 N. Kranjec, A. Galičič, I. Eržen et al. • The impact of ultrafine particles on daily counts of deaths from respiratory diseases in the Municipality... number concentrations data monitoring was medium long observation period. In epidemiological ecological temporal variability studies up un­til now, health effect of UFPs in outdoor air at the population level was observed both in short and long observation periods. In the study of Penttinen et al. [28, 30], the period of observation was six months long, in the study of Delfinno et al. [27], Brüskeet et al. [22], Leitteet et al. [16], Karakatsaniet et al. [25] and Chung et al. [40] the period of observation was from six months to two years long. Six years and a half [41] and seven-year observation period [29] present long periods of observation. Figure 1 shows the temporal variability association between periods with higher daily counts of deaths from respiratory diseases and higher daily UFP number concentrations. UFP health effect has already been evidenced in some previous studies. Leitte et al. [16] have proven po­sitive association between UFPsand emergency room visits for 0.05-0.10 acute exacerbation of respiratory diseases. Penttinen et al. [30] have proven a positive association between UFP number concentrations and asthma exacerbation. The observed temporal variability association for longer periods with heightened daily counts of deaths from respiratory diseases and higher daily UFP number concentrations can be contributed to time delayed effects from exposure to the observed health outcome, in the case of this study to the heightened daily counts of deaths from respiratory diseases. In previous studies, it has already been recognized that out­door air pollution not only on the day of the exposure but also for se­veral preceding days affect daily counts of deaths on a given day [42– 45]. It has been discovered that long-term health effects of the outdoor air pollution can persist up until a month [45, 46]. difficulties of data collection We had some difficulties with collection and preparation of data of daily UFP number concentrations in outdoor air. In the years 2012 and 2013, in total, 40.5 % of data were missing. The biggest part of missing data was in the year 2012 (from January to March 2012 and the first half of July 2012), less data was missing in 2013 (the first half of February 2013). The reason behind the missing measurement data is consequen­tial to the control and validation of measurement equipment and mainte­nance of measuring equipment [33]. UFPs in outdoor air and UFP health effects present in science a relatively new research field that is why it is important to know that on the European level there is no pre­scribed method of UFP measurement on the regulatory level [10]. Kukec et al. [47] have already emphasized the complications with the collec­tion of environmental data, which is essential for association with health data at the population level. In the future, the availability and quality of exposure to coarse particles data in outdoor air should be improved. One of the most important challenges in future research still presents the standardization of measuring equipment and technique for UFP mea­surements as well as the inclusion of UFPs in the routine system of the national network for monitoring air quality [47]. © Inštitut za sanitarno inženirstvo, 2016 The impact of ultrafine particles on daily counts of deaths from respiratory diseases in the Municipality... • N. Kranjec, A. Galičič, I. Eržen et al. In the literature review of outdoor air pollution and health effect at the population level, Galičič et al. [48] have also concluded that collection of suitable and quality environmental data presents one of the most frequent limitations in epidemiological ecological studies. Strengths and limitations of our study Our study is the first study in the field of the investigation of UFP ef­ fect in outdoor air on public health in Slovenia, which is why we have come to some limitations of our study. The biggest limitation of our study presents missing the environmental data of daily UFP number concentrations. The second limitation is related to the small popula­ tion and consequently less daily counts of deaths from respiratory diseases. Nevertheless, our study can be considered as relevant, be­ cause the area of observation was not yet investigated in Slovenia. Even though UFP number concentration data was gathered within the UFIREG project, the authors of this study were acquainted with the use of measuring equipment, and that the acquired knowledge would be used in the future for measurements of UFP number con­ centrations in other parts of Slovenia, which are most burdened with outdoor air pollution. In the future, research Future research specific population groups should be considered Research of the UFP effect in outdoor air on public health is a new sci­entific field in public health that is why the possibilities for the future research are numerous. Studies up until now on the one hand show statistically significant association between the effect of UFPs of diffe­rent sizes in outdoor air on public health at the population level [16, (children, elderly, ill and poor), because the exposure to outdoor air pollution levels in this population 30], and on the other hand the effect is not shown for some UFP sizes groups has an immense ranges [16, 28]. For confirmation of UFPs in outdoor air effect on pub- health effect. lic health, further temporal and spatial variability epidemiological eco­ logical studies are needed. Galičič et al. [48] and Kukec et al. [49, 50] have already emphasized and recommended the investigation of the effect of outdoor air pollution, also of UFPs, on smaller spatial units with a thick web of the observed units, with the purpose to undertake the exact exposure assessment. The observed population of studies on the population level was repre­ sentative for the whole population. In the future, research specific po­ pulation groups should be considered (children, elderly, ill and poor), because the exposure to outdoor air pollution levels in this population groups has an immense health effect [51]. In the past, UFP number concentrations in outdoor air have been col­ lected only within the UFIREG project. Routine monitoring of UFP number concentrations in outdoor air should be enlisted in the national network for monitoring air quality, which is administered by Slovenian Environment Agency. Within the national network for monitoring air quality, in January 2016 data collection of PM10 concentrations was collected on 15 measuring sites, and PM2.5 concentrations were mea­ sured on 4 measuring sites [50]. International Journal of Sanitary Engineering Research Vol. 10 . No. 1/2016 43 N. Kranjec, A. Galičič, I. Eržen et al. • The impact of ultrafine particles on daily counts of deaths from respiratory diseases in the Municipality... UFP number concentrations in outdoor air are slightly higher in winter. The possibilities for future research in the field of UFP health effect in outdoor air on public health also presents chemical and microbiologi­cal composition of UFPs and UFP health effect together with other out­door air pollutants (multiple effects, synergistic and antagonistic inter­actions). It has been established that UFPs of various sizes also have different chemical composition, which is also associated with the source and age of UFPs [52]. concLuSIonS Temporal variability of daily counts of deaths from respiratory diseases and UFP number concentrations in outdoor air during the year have significant seasonal pattern. UFP number concentrations in outdoor air are slightly higher in winter, when also daily counts of deaths from res­piratory diseases are slightly higher. Thus temporal variable association between the periods of higher daily counts of deaths from respiratory disease and higher daily UFP number concentrations has been proven. Research of the UFP effects in outdoor air on public health is a new scientific field in public health, which because of its complexity needs an interdisciplinary approach. Acknowledgements Authors of this study would like to thank the members of UFIREG project for providing outdoor air pollution data and the National Insti­tute of Public Health for providing mortality data. reFerenceS [1] Kakovost zraka v Sloveniji v letu 2014: http://www.arso.gov.si/zrak/ kakovost %20zraka/poro %C4 %8Dila %20in %20publikacije/ porocilo_2014.pdf. (28. 12. 2015) [2] European Environment Agency. Air quality in Europe – 2015 report. Luxembourg: Publications Office of the European Union, 2015. [3] Holmes NS. A review of particle formation events and growth in the atmosphere in the various environments and discussion of mechanistic implications. Atmospheric Environment 2007; 41 (10): 2183–201. [4] Knibbs LD, Cole-Hunter T, Morawska L. A review of commuter exposure to ultrafine particles and its health effects. Atmospheric Environment; 2014; 45: 2611–22. [5] Morawska L, Moore MR, Ristovski ZD. Health Impacts of Ultrafine particles. In: Desktop Literature Review and Analysis. Canberra: Australian Government. Department of the Environment and Heritage 2004: 42–161. [6] Kittelson DB. Engines and nanoparticles: a review. J Aerosol Sci1998; 29: 575–88. [7] Morawska L, Ristovski Z, Jayaratne ER, et al. Ambient nano and ultrafine particles from motor vehicle emissions: Characteristics, ambient processing and implications on human exposure. Atmospheric Environment 2008; 42 (35): 8113–38. [8] Giugliano M, Cernuschi S, Lonati G, et al. Ultrafine particles from combustion sources: sampling and measurement. Chemical Engineering Transactions 2008; 16: 7–14. [9] Health Effects Institute. Understanding the Health Effects of Ambient Ultrafine particles. V: HEI Review Panel on Ultrafine particles. HEI Perspectives 3. Boston: Health Effects Institute 2013: 7–67. © Inštitut za sanitarno inženirstvo, 2016 The impact of ultrafine particles on daily counts of deaths from respiratory diseases in the Municipality... • N. Kranjec, A. Galičič, I. Eržen et al. [10] Gobec M, Cvahte J, Pavlinec P, et al. UFIREG – “Ultrafinidelci – prispevek k razvoju regionalne in evropske okoljske in zdravstvene politike”. IJSER 2014; 8 (1): 56–61. [11] Rückerl R, Schneider A, Breitner S, et al. Health effects of particulate air pollution: A review of epidemiological evidence. Inhal Toxicol 2011; 23 (10): 555–92. [12] Ma N, Birmili W. Estimating the contribution of photochemical particle formation to ultrafine particle number averages in an urban atmosphere. Sci Total Environ 2015; 512-513: 154–166. [13] Barone TL, Zhu Y. The morphology of ultrafine particles on and near major freeways. Atmospheric Environment 2008; 42 (28): 6749–58. [14] Olvera HA, Perez D, Clague JW, et al. The Effect of Ventilation, Age, and Asthmatic Condition on Ultrafine Particle Deposition in Children. Pulm Med 2012. [15] Oberdörster G, Elder A, Finkelstein J, et al. Assessment of Ambient UFPS Health Effects: Linking sources to exposure and responses in Extrapulmonary Organs. Rochester PM Center Report. University of Rochester 2010: 8–15. [16] Leitte AM, Schlink U, Herbarth O, et al. Size-Segregated Particle Number Concentrations and Respiratory Emergency Room Visits in Beijing, China. Environ Health Perspect 2011; 119 (4): 508–13. [17] Shah AP, Pietropaoli AP, Frasier LM, et al. Effect of Inhaled Carbon Ultrafine Particles on Reactive Hyperemia in Healthy Human Subjects. Environ Health Perspect 2008; 116(3): 375–80. [18] Klot SV, Peters A, Aalto P, et al. Ambient Air Pollution Is Associated With Increased Risk of Hospital Cardiac Readmissions of Myocardial Infarction Survivors in Five European Cities. Circulation 2005; 112 (20): 3073–9. [19] Lanki T, Pekkanen J, Aalto P, et al. Associations of traffic related air pollutants with hospitalisation for first acute myocardial infarction: the HEAPSS study. Occup Environ Med 2006; 63 (12): 844–51. [20] Brown DM, Donaldson K, Borm PJ, et al. Calcium and ROS-mediated activation of transcription factors and TNF-cytokine gene expression in macrophages exposed to ultrafine particles. Am J Physiol Lung Cell MolPhysiol 2004; 286: 344–53. [21] McCreanor J, Cullinan P, Nieuwenhuijsen MJ, et al. Respiratory Effects of Exposure to Diesel Traffic in Persons with Asthma. N Engl J Med 2007; 357: 2348–58. [22] Brüske I, Hampel R, Socher MM, et al. Impact of Ambient Air Pollution on the Differential White BloodCell Count in Patients with Chronic Pulmonary Disease. InhalToxicol 2010; 22 (3). [23] Avogbe PH, Ayi-Fanou L, Autrup H, et al. Ultrafine particulate matter and high-level benzene urban air pollution in relation to oxidative DNA damage. Carcinogenesis 2005; 26(3): 613–20. [24] Renwick LC, Brown D, Clouter A, et al. Increased inflammation and altered macrophage chemotactic responses caused by two ultrafine particle types. Occup Environ Med 2004; 61: 442–7. [25] Karakatsani A, Analitis A, Perifanou D, et al. Particulate matter air pollution and respiratory symptoms in individuals having either asthma or chronic obstructive pulmonary disease: a European multicentre panel study. Environ Health 2012; 11: 75–91. [26] Martins LD, Martins JA, Freitas ED, et al. Potential health impact of ultrafine particles under clean and polluted urban atmospheric conditions: a model-based study. Air QualAtmos Health 2010; 3(1): 29–39. [27] Delfino RJ, Staimer N, Tjoa T, et al. Air Pollution Exposures and Circulating Biomarkers of Effect in a Susceptible Population: Clues to Potential Causal Component Mixtures and Mechanisms. Environ Health Perspect 2009; 117 (8): 1232–8. [28] Penttinen P, Timonen KL, Tiittanen P, et al. Number Concentration and Size of Particles in Urban Air: Effects on Spirometric Lung Function in Adult Asthmatic Subjects. Environ Health Perspect 2001; 109 (4): 319–23. International Journal of Sanitary Engineering Research Vol. 10 . No. 1/2016 45 N. Kranjec, A. Galičič, I. Eržen et al. • The impact of ultrafine particles on daily counts of deaths from respiratory diseases in the Municipality... [29] Kettunen J, Lanki T, Tiittanen P, et al. Associations of Fine and Ultrafine Particulate Air Pollution With Stroke Mortality in an Area of Low Air. Stroke 2007; 38: 918–22. [30] Penttinen P, Timonen KL, Tiittanen P, et al. Ultrafine particles in urban air and respiratory health among adult asthmatics. EurRespir J 2001; 17 (3): 428–35. [31] Prebivalstvo po starosti in spolu, občine, Slovenija, polletno: http:// pxweb.stat.si/pxweb/Dialog/varval.asp?ma=05C4002S&ti=&path=../ Database/Dem_soc/05_prebivalstvo/10_stevilo_preb/20_05C40_ prebivalstvo_obcine/&lang=2. (3. 7. 2015). [32] Opredelitev virov delcev PM10 v Ljubljani. Ljubljana: Slovenian Environment Agency: http://www.arso.gov.si/zrak/kakovost %20zraka/ poro %C4 %8Dila %20in %20publikacije/ViriLjubljanaBF.pdf. (9. 7. 2015) [33] UFIREG. Data collection and methods. Report. Dresden: Teschnsche Universität Dresden, 2014. [34] International Statistical Classification of Diseases and Related Health Problems 10th Revision. http://apps.who.int/classifications/icd10/ browse/2015/en. (13. 7. 2015). [35] Kraigher A. Epidemiološko spremljanje nalezljivih bolezni v Sloveniji v letu 2012. Ljubljana: National Institute of Public Health, 2013. [36] Kraigher A. Epidemiološko spremljanje nalezljivih bolezni v Sloveniji v letu 2013. Ljubljana: National Institute of Public Health, 2014. [37] Weschler CJ. Ozone’s impact on public health: contributions from indoor exposures to ozone and products of ozone-initiated chemistry. Environ Health Perspect 2006; 114: 1489–96. [38] Kittelson DB. Engine and nanoparticles: A review. J Aerosol Sci 1998; 29 (5/6):575–88. [39] Obseg in sestava potniškega prevoza in prometa. Agencija RS za okolje. http://kazalci.arso.gov.si/?data=indicator&ind_id=711 (13. 4. 2016). [40] Chung M, Wang DD, Rizzo AM, et al. Association of PNC, BC, and PM2.5 Measured at a Central Monitoring Site with Blood Pressure in a Predominantly Near Highway Population. Int J Environ Res Public Health 2015; 12 (3): 2765–80. [41] Ostro B, Hu J, Goldberg D, et al. Associations of Mortality with Long-Term Exposures to Fine and Ultrafine Particles, Species and Sources: Results from the California Teachers Study Cohort. Environ Health Perspect 2015; 123 (6): 549–56. [42] Kelsall JE, Samet JM, Zeger SL, et al. Air pollution and mortality in Philadelphia: 1974-1988. Am J Epidemiol 1997; 146:750–62. [43] Schwartz J, Dockery DW. Increased mortality in Philadelphia associated with daily air pollution concentrations. Am Rev Respir Dis 1992; 145: 600–4. [44] Zanobetti A, Schwartz J, in Dockery DW. Airborne particles are a risk factor for hospital admissions for heart and lung disease. Environ Health Perspect 2000; 108: 1071–77. [45] Zanobetti A, Schwartz J, Samoli E, et al. The temporal pattern of respiratory and heart disease mortality in response to air pollution. Environ Health Perspect 2003; 111: 1188–93. [46] Schwartz J. The distributed lag between air pollution and daily deaths. Epidemiology 2000; 11: 320–6. [47] Kukec A, Jereb G, Zaletel-Kragelj L, et al. Kakovost zunanjega zraka kot determinant zdravja. IJSER. 2014; Special Edition: 4–18. [48] Galičič A, Zaletel-Kragelj L, Božnar MZ, et al. Methodology for defining the effects of outdoor air pollution on children’s health at the population level – a systematic review. IJSER 9 2015; (1): 35–49. [49] Kukec A, Galičič A, Kranjec N, et al. Health exposure assessment methods for particles of varios sizes in outdoor air pollution: availability and quality of data. In: Lipič K, Rižnar K, Novak P (eds.) Gospodarno z © Inštitut za sanitarno inženirstvo, 2016 The impact of ultrafine particles on daily counts of deaths from respiratory diseases in the Municipality... • N. Kranjec, A. Galičič, I. Eržen et al. viri za sonaravni razvoj Slovenije: strokovno posvetovanje 2016, Moravske Toplice, 7. in 8. april 2016. 2016; 181–6. [50] Kukec A, Galičič A, Eržen I, et al. Pristopi in izzivi pri povezovanju zdravstvenih in okoljskih podatkov za ocenjevanje in obvladovanje okoljskih tveganj. In: Metodologije ocen vplivov tveganja, Okrogla miza Sveta zavarovanje okolja SAZU z mednarodno udeležbo, Ljubljana, 14. januar 2016. 2016; 31–7. [51] World Health Organisation. Frequently Asked Questions, Ambient and Household Air Pollution and Health, Update 2014. http://www.who.int/ phe/health_topics/outdoorair/databases/faqs_air_pollution.pdf?ua=1 (17. 10. 2015). [52] Ramgolam K, Favez O, Cachier H, et al. Size-partitioning of an urban aerosol to identify particle determinants involved in the proinflammatory response induced in airway epithelial cells. Part FibreToxicol 2009; 6: 10. International Journal of Sanitary Engineering Research Vol. 10 . No. 1/2016