Quantify Individual Variation Of Fine Particulate Matter Exposure In Urban And Rural Homes In Sichuan

Fine particulate matter(PM_2.5)is one of the major air pollutants in China.Overexposure to PM_2.5 can cause harm to the respiratory system and cardiovascular system,which is an important risk factor for human health.Studying individual exposure to PM_2.5 is of great significance,and the PM_2.5 real-time monitor is important technical support.At present,most of the related studies focused on a certain group,while the individual exposure in the family unit has been rarely reported,and the difference of individual exposure remained unknown.Indoor PM_2.5 exposure is the main risk factor for individual exposure.In 2022,the State Administration of Market Supervision and Administration and the Standardization Administration of China jointly issued the Indoor Air Quality Standard（GB/T 18883-2022）,which stipulates the daily average concentration limit of indoor PM_2.5（50μg/m³）for the first time.Based on this background,this study independently designed and customized fixed and portable PM_2.5 real-time monitors with good stability and high precision,innovatively coupled with high-resolution behavior pattern lists,providing basic data and mode reference for finely characterizing individual PM_2.5 exposure risk assessment and prevention and control in residential households.Two kinds of real-time monitoring instruments were used to obtain the real-time concentration of individual exposure microenvironment of residents,and 297 PM_2.5real-time exposure curves were drawn in combination with detailed temporal activity patterns,to clarify the PM_2.5 exposure characteristics of residents（daily average exposure concentration level,microenvironmental exposure weight,exposure contribution and exposure intensity,etc.）,and to analyze the individual exposure differences of 47 households（160 people）.Taking103 elderly and primary school students（from 2 urban primary schools and 2 rural primary schools）who are sensitive to PM_2.5 exposure as representatives,this paper explores the urban-rural differences in PM_2.5 exposure of individual families.The main conclusions are as follows:（1）There were significant household individual variations in PM_2.5 exposure characteristics,and the risk of daily average exposure and high instantaneous exposure was positively correlated with age.In urban households,for example,the daily average exposure concentrations were 82.5±13.0μg/m³,87.4±14.9μg/m³,84.0±11.4μg/m³,83.6±11.3μg/m³and 82.1±10.0μg/m³for elderly men,elderly women,middle-aged men,middle-aged women and children respectively,all exceeding 50μg/m³,and whose average peak intra-day exposure concentrations for elderly males,elderly females,middle-aged males,middle-aged females and children in urban residential households were 308.9±264.2μg/m³,437.2±309.2μg/m³,280.3±211.9μg/m³,320.8±223.9μg/m³and 196.0±82.3μg/m³respectively.In rural households,the daily average exposure concentrations for elderly males and elderly females during the study period were essentially comparable and significantly higher than for children.The risk of PM_2.5 exposure increased with the age of the individual,and gender differences were mainly found in the elderly in urban residential households（women’s exposure was greater than men’s）.（2）Variations in exposure characteristics in each microenvironment are the main reason for the differences in individual PM_2.5 exposure.For residents of the cities tested,the exposure intensity in the living room was greater than 1.0,with the living room making the highest contribution to the exposure of children（41.7%）,followed by older men（36.6%）,older women（36.4%）and middle-aged women（34.4%）,significantly higher than that of middle-aged men（25.4%）;the exposure intensity in the bedroom was less than 1.0,with the bedroom contributing to individual exposure in the following order middle-aged females（43.6%）>children（42.1%）>elderly males（39.1%）>middle-aged males（37.4%）>elderly females（36.7%）.（3）There were significant urban-rural variations in PM_2.5 exposure between elderly and primary school children,who were sensitive members of the household PM_2.5 exposure.The daily average PM_2.5 exposure concentration was 42.1%higher for rural elderly than urban elderly during the study period,with the bedroom contributing significantly more to the exposure of rural elderly（48.5%vs 34.2%）,the intensity of exposure in the kitchen was significantly higher for rural elderly（2.36）than urban elderly（1.15）.For term time and holidays,rural primary school students had 55.9%and 32.4%higher intra-day exposure than urban primary school students respectively,urban primary school students had no significant difference in exposure levels during school hours and holidays,while primary school students in rural households had higher PM_2.5 exposure during term time（26.6%higher than during holidays）.The average PM_2.5 exposure concentration of rural primary school students in classrooms was 1.45 times higher than that of urban primary school students,while urban primary school students were more intensely exposed in classrooms（0.93 vs 0.72）.