Politehnika Nova Gorica
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UNIVERSITY OF NOVA GORICA GRADUATE SCHOOL AN ENVIRONMENTAL MODEL FOR THE RELATIONSHIP BETWEEN AIR POLLUTION AND RESPIRATORY DISEASES IN CHILDREN – THE ZASAVJE CASE DISSERTATION Andreja Kukec Mentors: Prof. Lijana Zaletel-Kragelj, PhD Prof. Ivan Eržen, PhD Nova Gorica, 2013 UNIVERZA V NOVI GORICI FAKULTETA ZA PODIPLOMSKI ŠTUDIJ OKOLJSKI MODEL ZA POVEZANOST MED ONESNAŽENOSTJO ZRAKA IN BOLEZNIMI DIHAL PRI OTROCIH – PRIMER ZASAVJE DISERTACIJA Andreja Kukec Mentorja: Prof. dr. Lijana Zaletel-Kragelj Prof. dr. Ivan Eržen Nova Gorica, 2013 ABSTRACT BACKGROUND. Several epidemiological studies demonstrated association between outdoor air pollution exposure and respiratory diseases among children. In terms of outdoor air pollution, narrow valleys and closed basins present particularly critical areas. The aim of the study was to assess the association between the frequency of consultations in primary health care units due to respiratory diseases in children and outdoor air pollution in the Zasavje. METHODS. Mixed methods design was used to assess the association between health and environmental data. The research process was divided into six phases. In each phase, a separate study was done, of which the first four studies were preparative descriptive studies for the fifth and sixth analytical studies. The study population was all children, aged 1-11 years, residing in the Zasavje region permanently, who visited the CHC (Zagorje, Trbovlje or Hrastnik) due to selected respiratory diseases in the periods of observation. Time-trend study was performed for the 6-year period between January 1, 2006 and December 31, 2011. The association between the observed outcome, explanatory factors and covariates was analysed using Poisson regression models. A spatial multiple-group study was performed for the 1-year period between January 1, 2011 and December 31, 2011. The association between the observed outcome and explanatory factors was analysed by using the Bayesian hierarchical models. RESULTS. The results of the time-trend analysis have shown a positive and statistically significant correlation between the number of consultations due to respiratory diseases and PM10 in the municipalities of Zagorje ob Savi and Trbovlje, and O3 in the municipality of Zagorje ob Savi. The results of the spatial association analysis in established small spatial units have shown a positive and statistically significant association in the effect of yearly average SO2 concentration. CONCLUSION. It can be concluded, that there is certain relationship between the number of consultations in primary health care units due to respiratory diseases in children and the outdoor air pollution at the population level in the region of Zasavje. The association was more apparent in the models of temporal association, and less apparent in the models of spatial association. Considering the identified deficiencies, the results of the presented study could present an important foundation in planning future studies in the observed area and other areas with a similarly complex terrain. KEY WORDS: outdoor air pollution, respiratory diseases, children, ecological time-trend study, ecological spatial multiple-group study, small spatial units, Zasavje i IZVLEČEK IZHODIŠČE. Številne epidemiološke raziskave so pokazale povezanost med onesnaženostjo zunanjega zraka in boleznimi dihal pri otrocih. Posebno kritična območja glede onesnaženosti zunanjega zraka predstavljajo ozke doline in zaprte kotline. Namen raziskave je bil oceniti povezanost med obiski otrok na primarnem zdravstvenem varstvu in onesnaženostjo zunanjega zraka v Zasavju. METODE. Za oceno povezanosti med zdravstvenimi in okoljskimi podatki so bile uporabljene kombinacije različnih metod. Raziskovalni proces je bil razdeljen na šest faz. V vsaki fazi je bila izvedena ločena raziskava, od katerih so bile prve štiri raziskave po zasnovi opisne ter peta in šesta analitični. Opazovana populacija v raziskavi so bili vsi otroci, stari med 1 in 11 let s stalnim prebivališčem v Zasavju, ki so v obdobju opazovanja obiskali zdravstveni dom (Zagorje , Trbovlje ali Hrastnik) zaradi izbranih bolezni dihal. Raziskava časovnega trenda je bila izvedena za 6-letno obdobje od 1. januarja 2006 do 31. decembra 2011. Za analizo povezanosti med opazovanim zdravstvenim izidom, pojasnjevalnimi spremenljivkami in dejavniki ozadja so bili uporabljeni Poisson-ovi regresijski modeli. Prostorska analiza je bila izvedena za 1-letno obdobje med 1. januarjem 2011 in 31. decembrom 2011. Za analizo povezanosti med opazovanim zdravstvenim izidom in pojasnjevalnimi spremenljivkami so bili uporabljeni Bayes-ovi hierarhični modeli. REZULTATI. Pri rezultatih časovne analize se je pokazala pozitivna in statistično značilna povezanost med obiski zaradi bolezni dihal in PM10 v občini Zagorje ob Savi in Trbovlje ter O3 v občini Zagorje ob Savi. Pri rezultatih prostorske povezanosti na oblikovanih majhnih prostorskih enotah se je pozitivna in statistično značilna povezanost pokazala v primeru povprečne letne koncentracije SO2. ZAKLJUČEK. Zaključim lahko, da v Zasavju obstaja določena povezanost med številom obiskov otrok zaradi bolezni dihal na primarnem zdravstvenem varstvu in onesnaženostjo zunanjega zraka na populacijski ravni. Povezanost je bila bolj očitna v modelih časovne povezanosti in manj v modelih prostorske povezanosti. Ob upoštevanju opredeljenih pomanjkljivosti bodo rezultati predstavljenega dela lahko predstavljali pomemben temelj pri načrtovanju nadaljnjih raziskav na obravnavanem območju ali drugih razgibanih reliefih. KLJUČNE BESEDE: onesnaženost zunanjega zraka, bolezni dihal, otroci, ekološka raziskava časovnih trendov, več skupinska prostorska ekološka raziskava, majhne prostorske enote, Zasavje ii TABLE OF CONTENTS 1 INTRODUCTION 1 1.1 Outdoor air pollution 1 1.2 Outdoor air pollution and health effects 1 1.3 Outdoor air pollution in Zasavje 3 1.4 Methods for studying the relationship between outdoor air pollution and 4 health effects 1.4.1 Linkage methods for health and environment 4 1.4.2 Sources of data for studying the relationship between outdoor air pollution and health 5 effects at the population level 1.4.2.1 Health data 5 1.4.2.2 Environmental data 6 1.4.3 Review of studies exploring the temporal or spatial relationship between health 7 effects and outdoor air pollution at the population level 1.4.3.1 Temporal studies 7 1.4.3.1.1 Several air pollutants as explanatory factors 7 1.4.3.1.2 PM10 as explanatory factor 9 1.4.3.1.3 SO2 as an explanatory factor 11 1.4.3.1.4 NO2 as explanatory factor 12 1.4.3.1.5 O3 as explanatory factor 13 1.4.3.1.6 Studies exploring the temporal relationship between health effects and outdoor 15 air pollution in Slovenia 1.4.3.2 Spatial studies 15 1.5 Regulations relating to outdoor air pollutants in Europe, Slovenia and 17 Zasavje region to protect people’s health 2 AIM AND OBJECTIVES 19 iii 3 MATERIALS AND METHODS 21 3.1 Design of the study 21 3.2 Period of observation 21 3.3 Population of observation 21 3.4 Area of observation 22 3.5 Methods by phases 23 3.5.1 Phase I: Temporal variability of health data and assessment of the data quality 23 3.5.1.1 Observed temporal units 23 3.5.1.2 Origin and characteristics of health data 23 3.5.1.3 Assessment of the completeness and quality of health data 24 3.5.1.4 Description and temporal variability of health data 25 3.5.2 Phase II: Temporal variability of immission data and assessment of the data quality 25 3.5.2.1 Observed temporal units 25 3.5.2.2 Origin and characteristics of immission data 25 3.5.2.3 Assessment of completeness and quality of immission data 27 3.5.2.4 Description and temporal variability of immission data 27 3.5.3 Phase III: Methodology of determination of small spatial units 28 3.5.3.1 Area of observation 28 3.5.3.2 Periods of observation 28 3.5.3.3 Assessment of completeness and quality of emission data 28 3.5.3.4 The process of modelling of dispersion of air pollution 29 3.5.3.5 Determination of small spatial units for the relationship analysis 32 3.5.4 Phase IV: Assessment of the presence and importance of selected potential 34 confounding factors at the level of small areas 3.5.4.1 Design of the study 34 3.5.4.2 Population and period of observation 34 iv 3.5.4.3 Data collection 34 3.5.4.4 Selection of potential confounders 34 3.5.4.5 The procedure for assessment of frequency and importance of potential confounders 36 3.5.4.5.1 Data used in the procedure 36 3.5.4.5.2 Relationship analysis 37 3.5.4.6 Spatial distribution of potential confounding factors 38 3.5.5 Phase V: Time-trend study 39 3.5.5.1 Observed temporal units 39 3.5.5.2 Outcome of the observation 39 3.5.5.3 Explanatory factors 39 3.5.5.4 Covariates 39 3.5.5.4.1 Meteorological data 40 3.5.5.4.2 Seasonal data 40 3.5.5.5 Methods of temporal relationship analysis 40 3.5.6 Phase VI: Spatial multiple-group study 41 3.5.6.1 Observed spatial units 42 3.5.6.2 Outcome of the observation 42 3.5.6.3 Explanatory factors 44 3.5.6.4 Methods of spatial relationship analysis 44 3.5.6.5 Software package 45 3.6 Ethical considerations 45 4 RESULTS 47 4.1 Phase I: Temporal variability of health data 47 4.1.1 Data description 47 4.1.1.1 Number of consultations for chronic respiratory diseases 47 4.1.1.2 Number of consultations for acute respiratory diseases 48 v 4.1.1.3 Number of consultations for all respiratory diseases 49 4.1.2 Assessment of the quality of health data 51 4.1.2.1 The distinction between consultations due to respiratory diseases and consultations due to 51 other diseases 4.1.2.2 The distinction