Elsevier

Energy and Buildings

Volume 173, 15 August 2018, Pages 623-633
Energy and Buildings

Spring-time PM2.5 elemental analysis and polycyclic aromatic hydrocarbons measurement in High-rise residential buildings in Chongqing and Xian, China

https://doi.org/10.1016/j.enbuild.2018.06.003Get rights and content

Abstract

The mass concentration and the elemental composition of PM2.5 and polycyclic aromatic hydrocarbons were measured in 30 residential apartments during spring in the city of Xian and Chongqing, China. A total of 45 major, minor and trace elements were determined by X-Ray Fluorescence analysis. The carbonaceous species were determined with the thermal–optical transmittance technique. The daily PM2.5 mass concentration ranged from 25 to 140 µg/m3. The following compounds had higher concentrations outdoors than indoors and had higher concentrations in Xi'an than in Chongqing: Na, Al, Si, K, Mn, Fe, Cu, Zn, Br. Sulfur had higher concentrations in Chongqing than in Xi'an and had higher concentrations outdoors than indoors. For the strongly enriched elements (enrichment factor > 100) like S, Cl, Zn, Br, an anthropogenic origin can be suggested. In this study, the average ratio of organic carbon to elemental carbon was 4.9, indicating the possible presence of secondary organic carbon.

Introduction

Many toxicological studies have suggested that exposure to particulate matter (PM) leads to adverse health effects, particularly cardiovascular and respiratory diseases [1], [2], [3]. Carbonaceous material is a large component of urban particulate matter and plays an important role in urban air quality, health, visibility, and climate [4], [5], [6]. Carbonaceous species, including organic carbon (OC) and elemental carbon (EC), are major components of PM. EC, also known as black carbon (BC) or soot, is the non-volatile, light-absorbing portion emitted directly into the atmosphere from combustion sources. OC contains compounds with a wide range of molecular forms and volatilities. Moreover, elemental components constitute a small portion by mass of the particles, however, the existence of some heavy metals such as lead, arsenic, selenium, and iron, may exhibit detrimental health impact to human body even in trace amount [7]. Therefore, it is necessary to know the characteristics of the fine particles to develop effective strategy for the control of fine aerosol pollution.

As for assessing the sources of air pollution in highly populated urban areas, Kam et al conducted an investigation to assess on-road particulate (PM) composition in major roadways and surface streets in Los Angeles [8], and it was found that PM0.25 is heavily influenced by vehicular emissions, which is evident in its substantial contribution to total carbon (TC), including both EC and OC components, while PM2.5-0.25 and PM10-2.5 are less impacted by on-road sources. In major urban areas close to sea port, PM2.5 mass was mainly composed by secondary inorganic aerosols and particulate organic matter, reflecting the simultaneous contribution of both regional and local emission sources [9]. Either sampling on a moving vehicle or sampling in a fixed position, the samplers will be finally analyzed in a laboratory to obtain the detailed PM composition.

The indoor environment has long been identified as a high priority for health, since people in urban area normally spend 80–90% of their time indoors [10]. Several recent indoor/outdoor studies focused on PM and its chemical characteristics [11], [12], [13], [14], [15], [16], the contribution of outdoor PM to indoor PM, and health impacts. Fine particles (PM2.5) are composed of metal oxides, black and elemental carbon, primary and secondary organic compounds, sulfate, nitrate, ammonium and hydrogen ions [17]. Even though most elements are linked with outdoor emission sources (e.g. incinerators, motor vehicles, metal industries, and coal or oil combustion), they may still contribute significantly to indoor particles through air infiltration. Other sources of elements may include crustal material from road dust, construction activities, tire/brake wear, cement factories, etc.

China has the most number of cities with urban population over 1 million in the world. According to the demographia research group in 2017, there are 102 Chinese cities with over 1 million people in the "urban area", as defined by the group's methodology [18]. China also has one of the highest PM2.5 levels in the world [19]. It is well recognized that carbonaceous aerosols are the important components of the urban PM2.5 particles in China, accounting for up to 40% of the PM2.5 mass [20], [21], [22], [23], [24]. Pollution levels in urban areas of China are an important determinant of indoor air quality. Outdoor particle pollution, including polycyclic aromatic hydrocarbons (PAHs), elemental carbon (EC) and many elements, are important contributors to indoor levels of pollution, which are higher than levels experienced in developed countries that have mature air pollution management programs [25]. Systematic knowledge of chemical composition and source apportionment of PM2.5 is still lacking for the inside of China's residential buildings compared to several research studies conducted in cities outside China [26], [27], [28], [29], [30].

Understanding personal exposures to both air PM2.5 and PAHs—and how different sources contribute to individual exposures—has been considered an important first step in assessing the possible public health risks from these species in the urban environment. The objectives of this study are: (1) to comprehensively investigate PM2.5 mass concentration and characteristics of chemical compositions in fine particles in high-rise residential buildings in two China's big cities, Xi'an and Chongqing; (2) to preliminarily identify the sources of air pollutant to indoor air in high-rise residential buildings by the ways of elemental analysis and provide possible control strategies.

Section snippets

Sampling apartments

Xi'an city (34°15′N, 108°56′E) lies on the Guanzhong Plain in the south-central part of Shaanxi province in China, covers a main city area of 530 km2, and has a population of 9.5 millions. Dust storms caused by the rapid increase in temperature occur during March and April. Chongqing city (29°57′N, 106°55′E) is situated at the transitional area between the Qinghai-Tibet Plateau and the plain on the middle and lower reaches of the Yangtze River, covers a main city area of 5400 km2, and has a

PM2.5 mass concentration

The concentrations of PM2.5 observed in this study are considerably higher than the daily averages standards stipulated by the China's National Ambient Air Quality (PM2.5 = 75 µg/m3) and WHO standards (PM2.5 = 25 µg/m3). Comparisons with WHO Ambient Air Quality standards for PM2.5 suggest that the majority of homes in the pilot study exceed the standards, in some cases even by a factor of six (Fig. 3). Ambient air is a primary contributor to indoor environment quality in both unoccupied and

Conclusion

In order to understand how different sources contribute to individual exposures, the mass concentration and the elemental composition of PM2.5 and PAHs were measured and analyzed in 30 high-rise residential apartments during spring in the city of Xian and Chongqing, China. The following conclusions can be made:

  • Outdoor particle pollution, including PAHs, EC and many elements, are important contributors to indoor levels of pollution in urban area of China. Using sulfur as a tracer for

Acknowledgment

The work presented in this paper is supported financially by the National Key Project of the Ministry of Science and Technology, China, on the causes and control technology of ambient air pollution through Grant No. 2016YFC0207101.

Conflict of interest

We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled.

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