Study On The Pollution Characteristics And Health Risks Of Ambient Particulate Matter In Urban Taiyuan,China

Numerous of epidemiological and toxicological studies have shown that atmospheric particles,especially fine particles can damage the respiratory system and cardiovascular system,causing cardiopulmonary diseases and even death.The degree of damage has a great relationship with concentration,size and chemical composition of the particles.As one of major energy and industrial bases in North China,Taiyuan suffers from severe air pollution,which has serious impact on the ecological environment and human health.It is significant for the prevention and control of air pollution to carry out research on the pollution characteristics,chemical composition and health effect of atmospheric particles in the main urban area of Taiyuan.Firstly,the air pollution characteristic radar chart,pollutants concentration,meteorological factors and the backward trajectory were used to analyze the characteristics and causes of the typical heavy pollution weather process in Taiyuan from2013 to 2019.Secondly,the daily mass concentrations of urban PM_2.5and PM₁₀from January 2013 to October 2015 and the daily number of non-accidental death?NAD?and cause-specific mortality in the residents aged more than 65 years old were obtained;and using a time-series analysis with generalized additive distributed lag model?DLM?,the potential harvesting effects was determined and the single-day and cumulative lag-day effect of PM on mortality were estimated.Finally,PM_2.5samples were collected from Oct11-16,2016,using medium-volume PM_2.5samplers on the 1.5 m,13 m,and 58 m above the ground of a high building.Heavy metals?HMs?Ti,Cr,Mn,Fe,Ni,Cu,Zn,As,Cd,Ba and Pb in PM_2.5were determined using inductively coupled plasma atomic emission spectroscopy?ICP-AES?.Pearson correlation analysis and principal component analysis were conducted to determine the relationship and identify the sources of these HMs.And non-carcinogenic risks and carcinogenic risks were quantitatively assessed using health evaluation models developed by the United States Environmental Protection Agency?US EPA?.Results showed:?1?From 2013 to 2019,there were 80 times of heavy pollution processes with a total of 134 days.The main pollutant was PM_2.5,followed by PM₁₀;and the seasonal distribution showed that heavy pollution processes mainly occurs in the heating season,especially in January and December.The heavy pollution process in urban Taiyuan from2013 to 2019 can be classified into five categories:coal-burning,secondary pollution,and dust storm conversion type;secondary pollution,and dust storm conversion type;coal-burning,secondary pollution,and vehicle emission conversion type;secondary pollution,dust storm and steel pollution conversion type;and comprehensive pollution type.?2?There were significant associations of PM_2.5and PM₁₀with daily mortality on the current day and within one week.When the exposure window was extended to lag 0-30days,a statistically significant increase in the cumulative effect estimates of PM_2.5and PM₁₀on cardiovascular diseases?CVD?,ischemic heart disease?IHD?,and myocardial infarction?MI?mortality,as well as PM_2.5on NAD was observed,while the associations of PM_2.5with respiratory disease?RD?and pneumonia mortality,PM₁₀with NAD and RD mortality were not statistically significant.?3?PM_2.5concentration decreased first and then increased with increasing height,and the average concentration of most heavy metals declined at daytime,while presented opposite trend at night.Source analysis showed that traffic emissions,coal combustion,and industrial processes were likely the dominant sources of the PM_2.5-bound heavy metals.The health risk values were all within an acceptable range,in the descending order of Cr,As,Ni,Cd and Cr,Pb,Zn,Cu.A higher non-carcinogenic risk was observed for children than for adults,which was contrary for the carcinogenic risk.The risk values of heavy metals except Cr decreased with height at daytime;while Cd,Ni and Pb first decreased and then increased at night,which presented opposite trend for As,and the profiles of Cu,Zn and Cr tended to increase at night.It was concluded that the characteristic of heavy pollution process in urban Taiyuan included short duration,heavy pollution,and PM_2.5as the primary pollutant.Heavy pollution weather processes were mainly affected by the combined effect of adverse weather conditions?such as high relative humidity?,primary pollutant emissions?coal combustion,motor vehicles,industrial production,etc.?,secondary conversion of precursor gases,regional transmission of sand and dust storm,and the pollutant transportation from the upwind regions;there were harvesting effect and cumulative effect of ambient PM_2.5and PM₁₀on the elderly residents'mortality due to RD and CVD in Taiyuan and those can be estimated quantitatively when using the broader time window,suggesting that the underestimation on the association of ambient particulate matter with NAD can be avoided using the present method in our study;it is significant for both architectural designers and residents to consider the possible entry of PM_2.5components into buildings and health risks to residents on different floors of buildings due to there are closely relationship between the vertical variation of health risks values and the contribution of PM_2.5pollution sources at different heights.