Study on sandstorm PM10 exposure assessment in the large-scale region: a case study in Inner Mongolia.

The current exposure-effect curves describing sandstorm PM10 exposure and the health effects are drawn roughly by the outdoor concentration (OC), which ignored the exposure levels of people's practical activity sites. The main objective of this work is to develop a novel approach to quantify human PM10 exposure by their socio-categorized micro-environment activities-time weighed (SCMEATW) in strong sandstorm period, which can be used to assess the exposure profiles in the large-scale region. Types of people's SCMEATW were obtained by questionnaire investigation. Different types of representatives were trackly recorded during the big sandstorm. The average exposure levels were estimated by SCMEATW. Furthermore, the geographic information system (GIS) technique was taken not only to simulate the outdoor concentration spatially but also to create human exposure outlines in a visualized map simultaneously, which could help to understand the risk to different types of people. Additionally, exposure-response curves describing the acute outpatient rate odds by sandstorm were formed by SCMEATW, and the differences between SCMEATW and OC were compared. Results indicated that acute outpatient rate odds had relationships with PM10 exposure from SCMEATW, with a level less than that of OC. Some types of people, such as herdsmen and those people walking outdoors during a strong sandstorm, have more risk than office men. Our findings provide more understanding of human practical activities on their exposure levels; they especially provide a tool to understand sandstorm PM10 exposure in large scale spatially, which might help to perform the different categories population's risk assessment regionally.

[Distribution Characteristics of Water-soluble Ions in Size-segregated Particulate Matters in Taiyuan].

The distributions of size-segregated particles (PM10) and water-soluble ions (WSIs) in Taiyuan were studied from July 2014 to April 2015 by TE-235 aerosol sampling and ion chromatography analyzing. As the results shown, the daily PM10 level was 173.7 µg·m-3, which exceeded the Grade Ⅱ limitation value in the Ambient Air Quality Standard (150 µg·m-3, GB 3095-2012). PM10 levels varied seasonally, and its were 199.1 and 194.2 µg·m-3 in winter and spring, respectively, which were much higher than those in summer. The PM10 size-segregated was bimodal distribution for the range of 0-0.95 and 3.0-7.2 µm. The concentration of WSIs was the highest in winter, followed by summer and spring. SO42-, NO3- and NH4+ were the main water soluble ions and accounted for 66% to 80% of the total WSIs. SO42-, K+, NH4+ and Cl- showed a unimodal distribution at <0.95 µm in all samples, while Ca2+ and Mg2+ showed a bimodal distribution at <0.95 µm and 3.0-7.2 µm. NO3- showed a unimodal size distribution at <0.95 µm in winter and spring, compared with a bimodal distribution at <0.95 µm and 3.0-7.2 µm in summer. By the correlation analysis, PM10 and WSIs decreased with the increase of wind speed in summer and winter other than in spring for the road-dust re-suspension by strong wind. Based on the ratio analysis of NO3-/SO42- and Mg2+/Ca2+, coal combustion was the main source of NO3- and SO42-, while Mg2+ and Ca2+ were mainly from the dust and coal combustion.