Association Research Between Air Pollution Exposure And Childhood Asthma And Construction Of Air Pollutants Exposure Prediction Models

Objective:In the past five years,domestic air pollution has gradually increased,and the relationship between air pollution and childhood asthma needs to be discussed in depth,effects of air pollution on health can be divided into long-term effect and acute effect.At present,there is no clear evidence at home and abroad whether the exposure of mothers during pregnancy to air pollution will increase the risk of children’s wheezing and asthma among long-term effect studies.There is no large-scale study in the northeast region to confirm the impact of air pollution on respiratory diseases among acute effect studies.The key of air pollution exposure research is to assess accurately the level of exposure to individual air pollution at different stages of different locations.This study will firstly explore the relationship between air pollution exposure during pregnancy and children’s wheezing and asthma through systematic review.Then we use time series analysis to explore the impact of air pollution data on childhood asthma visits in outpatients and emergency in large hospital institutions in Shenyang city.The spatial information model of air pollutants in Shenyang City would be established by using geographic information data to astimate air pollution levels in different districts in Shenyang city,relationship ananlysis between air pollution exposure in 2015 and childhood asthma inpatiant visits will be conducted,which will provide scientific research directions and pollutant assessment tools for future air pollution and health research.Methods:We systematically reviewed epidemiological studies published through June 6,2017 available in the MEDLINE and Web of Science databases.We included studies that examined the association between prenatal exposures to any air pollutants except tobacco smoke and the incidence or prevalence of“wheezing”or“asthma”from birth to 14 years of age.We extracted key characteristics of each included study using a template of predefined data items.The Critical Appraisal Skills Programme checklists were used to assess the validity of each included study.We conducted overall and subgroup meta-analyses for each summary exposure-outcome association.Pooled odds ratios（OR）with 95% confidence intervals（CI）were estimated by using a random effects model.For time-series studies,Data were collected for daily outpatient and emergency hospital visits,meteorological conditions,air pollutants(PM₁₀,PM_2.5,SO₂,NO₂,CO,ozone) during 2013-2017.A generalized additive model analysis was performed and stratified according to gender,season,age and infection type to assess the short-term effects of air pollutants on childhood asthma outpatient hospital admissions.Using R3.2.2 to conduct conditional Poisson regression analyses to compute effect estimates of all pollutants,over-dispersion,autocorrelation,and lag days were controlled.The spatial distribution model of pollutants is based on data of pollutants concentration,locations of pollutant monitoring stations,population density distribution data,the traffic trunks distribution map and the land use vector map of Shenyang city during the year of 2015.Monitor stations were divided into training set and test set.Using ARCGIS10.2 software spatial analysis function,the land use,road length and population quantity in different buffers around each monitoring point were calculated as dependent variables,and multiple linear regression models were constructed by SPSS19.0.Leave one out cross validation method was used for model verification.Air pollutions levels were calculated in different districts,childhood asthma inpatients rates were calculated by employing population counts and hospital visits data in Shenyang city.Relationship ananysis were conducted by SPSS19.0.Results:partⅠ:Eighteen studies met our eligibility criteria.There was notable variability in exposure assessment methods.The overall random effects risk estimates（95%CI）of different pollutants were 1.04（0.94-1.15）aromatic hydrocarbons（PAH）,1.04（1.01-1.07）NO₂,1.4（0.97-2.03）PM_2.5 for childhood wheeze and 1.07（1.01-1.14）NO₂,1（0.97-1.03）PM_2.5,1.02（0.98-1.07）SO₂,1.08（1.05-1.12）PM₁₀ for childhood asthma.Minimal heterogeneity was seen for PAH and SO₂,while some heterogeneity was observed for PM₁₀,PM_2.5 and NO₂.PartⅡ:A total of 130,555 childhood asthma outpatient and emergency hospital visits were considered in the analysis.The largest same-day effects on childhood asthma outpatient and emergency hospital visits in all age groups were associated with ozone,CO,NO₂,SO₂,PM_2.5,and PM₁₀,with the largest relative risks of 0.899（95%CI 0.824-0.981）,1.027（95%CI 1.001-1.053）,1.087（95%CI 1.023-1.154）,1.041（95%CI 1.004-1.078）,1.033（95%CI1.010-1.056）,and 1.047（95%CI 1.013-1.082）,respectively,per SD increments for different pollutants.Sex analysis indicated that males were more susceptible to PM_2.5,whereas females were more susceptible to NO₂ and PM₁₀.Impact of PM_2.5 on childhood asthma outpatients visits was not evident in this study.Part III:We used the monthly average concentration values of various pollutant monitoring stations,as well as the geographical factors such as land use type,road traffic and population density in Shenyang City in 2015 to build the spatial distribution model of six pollutants in the season and cold season,wherein the adjusted R² value of SO₂ and PM₁₀ models could reach over 80%,NO₂ and CO could reach over 70%,and the R² values of PM_2.5and O₃ prediction models were lower.Air pollutions levels in the nine districts were fully calculated,results showed SO₂,PM_2.5,and PM₁₀ in warm season were significantly associated with childhood asthma inpatient rate especially in children aged 6-10 year old.NO₂ was only associated with 6-10 year old group children,while O₃ in cold season was negatively associated with asthma inpatient rate.Conclusions:1.The overall and subgroup risk estimates from the meta-analyses showed statistically significant associations between prenatal exposures to NO₂,SO₂,and PM₁₀ and the risk of wheezing and asthma development in childhood.2.The results suggest association between acute exposure to traffic-related pollutants and asthma outpatient and emergency visits was strongest,especially during the cold season.3.The spatial distribution model of pollutants in Shenyang City constructed in this study can better predict the average annual dose of pollutants exposed throughout 2015 in any location in Shenyang.Relationship between air pollution exposure in long period and childhood asthma inpatient rates were significant in statistics.Our study showed effect of embient air pollution exposure in short term and long term exposure on childhood asthma was significantly different.This study can support the subsequent dose responses of large epidemiology research between exposure to air pollution and disease development.