Effects Of Mixed Exposure To Air Pollution On Mortality From Respiratory Diseases In Zibo

Respiratory diseases are common and frequently occurred diseases that seriously affect human health,mainly occurring in the trachea,bronchus,lungs and thorax,including chronic obstructive pulmonary disease（COPD）and lung cancer,which are one of the main causes of morbidity and mortality in the world.The results showed that about 3.91 million people died from chronic respiratory diseases worldwide in 2017,an increase of 18.0 percent since 1990.The prevention and treatment of respiratory diseases is one of the important public health problems.Risk factors for death from respiratory diseases include tobacco exposure,occupational exposure,air pollution,and severe respiratory infections,among which air pollution has received increasing attention.While some studies have found health effects from air pollution,the conclusions remained murky.Under normal environmental conditions,humans are exposed to a mixture of air pollution.However,most current studies only focused on the health effects of single pollutant,ignoring the effects of air pollution as a mixture,and the results may be skewed.Therefore,the adverse effects of mixed exposure of multiple pollutants on human health have attracted extensive attention of researchers.It is important to study exposures to multiple pollutants and their health hazards and to provide scientific evidence for air pollution control policies.In this study,the data of deaths from respiratory diseases in Zibo City as an example,Bayesian kernel machine regression（BKMR）and lagged weighted quantile sum regression（LWQS）,two multi-pollutant exposure research methods,were used to more fully estimate the relationships between air pollution as a mixture and death from respiratory diseases,provide references for similar studies,and provide scientific basis for local air pollutant control and prevention and treatment of vulnerable populations.Methods:Data of deaths from respiratory diseases（lung cancer and COPD）,air pollution and meteorological factors were collected in Zibo City,Shandong Province from January 1,2015 to December 31,2019.Descriptive epidemiological methods were used to analyze the general situation of deaths from respiratory diseases and their distribution characteristics.Describe the changes of air pollution and meteorological factors in the same period,and draw the corresponding time series graph.Based on weekly data,BKMR was used to explore the exposure-response relationships between air pollution mixtures and deaths from respiratory diseases,including total effects,single pollutant effects and interactions among pollutants,and to identify important air pollutant components.Based on the expose-response relationships in the previous step,and on the basis of daily data,LWQS was used to estimate the short-term delayed effects of air pollution mixture on respiratory disease deaths.Models were fitted in different subgroups to obtain time-varying effects of short-term exposure to air pollution in vulnerable populations.Results:1.During the study period,a total of 25 957 patients died of respiratory diseases in Zibo City.among which the male patients were more than the female patients.The average age of death cases was 74.36±12.42 years old,and the median age was 77 years old.The mortality rate of respiratory diseases in Zibo city was at a high level,but showed a trend of fluctuation decline.Most of the deaths were concentrated in December.January and February,and there was no significant seasonal pattern in lung cancer deaths.During the study period.the mortality rate of respiratory diseases in each county did not change significantly.Zhangdian District.located in the central area of Zibo City.kept at a low level,while other counties had high mortality rates.The levels of exposure to air pollution and meteorological factors showed significant seasonal changes.Except O₃,the concentrations of other air pollutants were high in winter and low in summer.2.The results of the BKMR analysis showed that the higher the concentration of air pollution mixture.the more deaths from respiratory diseases.A posteriori inclusion probability results showed that the posteriori inclusion probability of SO₂,O₃ and CO were greater than 0.4.which were more likely to affect deaths from respiratory diseases.The exposureresponse relationships were approximately linear,and there was no obvious interaction.Short-term LWQS analysis results showed that the contribution of O₃ reached the maximum within lag 0-2 days,and then decreased gradually.The contribution of SO₂ increased with the increase of lag days and reaches the maximum when the lag 5 days.The contribution of CO was relatively low and did not change much.3.There were more pollutants affecting the death from respiratory diseases in women（PM2.5.SO₂,O₃,CO）and the short-term lag effects were greater than that in men;Deaths from respiratory diseases in people aged 75 and older were more likely to be affected by air pollution than in people under 75;In the cold season,the presence of more pollutant components contributed to death from respiratory disease.The components of important pollutants in death from different respiratory diseases（lung cancer and COPD）were different.mainly gaseous pollutants.PM2.5SO₂,O₃ and CO were the main pollutants affecting death from respiratory diseases and COPD,and the effects of SO₂ and O₃ were larger.Black carbon was more likely to affect death from lung cancer,but the short-term lag effect was not statistically significant.Conclusions:1.This study found that the death rates of respiratory diseases in Zibo were at a relatively high level,but showed a decreasing trend year by year.Most of the deaths from respiratory diseases were concentrated in December,January and February in winter,and the mortality rate of respiratory diseases in Zhangdian District had always been at a low level.2.PM2.5,SO₂,O₃ and CO were more likely to have impacts on deaths from respiratory diseases,and SO₂ and O₃ had stronger short-term lag effects.The composition of air pollutants affecting the death from respiratory diseases varies among different groups,but the effects of air pollutants were generally stronger in the cold season,women,and people aged 75 and older.The components of important pollutants in death from different respiratory diseases（lung cancer and COPD）were different,mainly gaseous pollutants（SO₂,O₃ and CO）.