Comparison of PM2.5 Exposure in Hazy and Non-Hazy Days in Nanjing, China.

Ting Zhang,Wenqing Li,Steven N Chillrud,Zhenyang Liu,Beizhan Yan,Junfeng Ji,Yang Chen,Masha Pitiranggon

doi:10.4209/aaqr.2016.07.0301

Abstract

Fine particulate matter (PM2.5), levels of which are about 6 times the 2014 WHO air quality guidelines for 190 cities in China, has been found to be associated with various adverse health outcomes. In this study, personal PM2.5 exposures were monitored along a fixed routine that included 19 types of non-residential micro-environments (MEs) on 4 hazy days (ambient PM2.5 292 ± 70 μg m-3) and 2 non-hazy days (55 ± 16 μg m-3) in Nanjing, China using miniaturized real-time portable particulate sensors that also collect integrated filters of PM2.5 (MicroPEMs, Research Triangle Institute (RTI), NC). Gravimetric correction is necessary for nephelometer devices in calculating real-time PM levels. During both hazy and non-hazy days, personal PM2.5 levels were generally higher in MEs with noticeable PM2.5 sources than MEs serving as receptor sites, higher in open MEs than indoor MEs, and higher in densely populated MEs than MEs with few people. Personal PM2.5 levels measured during hazy and non-hazy days were 242 ± 91 μg m-3 and 103 ± 147 μg m-3, respectively. The ratio of personal exposure to ambient PM2.5 levels (rp/a ) was less than 1.0 and less variable on hazy days (0.85 ± 0.31); while it was larger than 1.0 and more variable on non-hazy days (1.71 ± 1.93), confirming the importance of local sources other than ambient during non-hazy days. Air handling methods (e.g., ventilation/filtration) impacted personal exposures in enclosed locations on both types of days. Street food vendors with cooking emissions were MEs with the highest personal PM2.5 levels while subway cars in Nanjing were relatively clean due to good air filtration on both hazy and non-hazy days. In summary, on hazy days, personal exposure was mainly affected by the regional ambient levels, while on non-hazy days, local sources together with ambient levels determined personal exposure levels.

Highlights

China has experienced severe air pollution over the past 10 years, as air pollutant emissions increased with rapid industrialization and relentless fossil fuel consumption (Zhang et al, 2012; Guo et al, 2014)
Personal PM2.5 exposures were monitored along a fixed routine that included 19 types of non-residential micro-environments (MEs) on 4 hazy days and 2 non-hazy days (55 ± 16 μg m–3) in Nanjing, China using miniaturized real-time portable particulate sensors that collect integrated filters of PM2.5 (MicroPEMs, Research Triangle Institute (RTI), NC)
Sampling Design In this study, personal PM2.5 exposure was monitored during part of this haze episode, while exposures during non-hazy days were monitored in late Dec. 2013 and in March 2014

Summary

Introduction

China has experienced severe air pollution over the past 10 years, as air pollutant emissions increased with rapid industrialization and relentless fossil fuel consumption (Zhang et al, 2012; Guo et al, 2014). Elevated levels of PM2.5 obscures the sky and leads to haze, an atmospheric phenomenon defined as Numerous epidemiological studies have observed significant associations of chronic exposure to toxic components of PM2.5, including heavy metals and polycyclic aromatic hydrocarbons (PAH), with adverse health effects such as respiratory or cardiovascular diseases and lung cancer (Cao et al, 2013; Li et al, 2013; Yang et al, 2013). Because of the high exposures to PM2.5, studies have indicated that PM2.5 has become the fourth leading health threat in China, accounting for enormous life expectancy loss and carcinogenic/non-carcinogenic diseases (Chen et al, 2013; Yang et al, 2013)

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