Characteristics and Health Effects of PM _2.5 in Different Indoor Microenvironments and Ambient Air in a Community in Xi’an, China: The Effect of Cooking in Household

Abstract

Xi’an, as one of the serious air pollution cities in western of China, many researches about the ambient air have developed. Limited has about the indoor air quality. In this study, PM_2.5 samples were collected from household, offices, and ambient air in one community during haze periods. The regular composition including organic carbon (OC), element carbon (EC), water soluble ions, element, and polycyclic aromatic hydrocarbons (PAHs) of PM_2.5 were discussed here. During the sampling time, ambient PM_2.5 was the highest dispersed, and then followed by the household and offices, and outdoor diffusion is one of the main sources for indoors. However, the cooking activities in household were also another source of PM_2.5 for household, with almost all the ratios of Kitchen/Sitting room (K/S) for different fractions were higher than 1. Though it has different composition in different environments, like organic matter (OM) in indoors attributed more than in ambient air, OM and water soluble ions were main parts of PM_2.5. NO₃- was a bit higher than SO₄^2-, which might because of the decrease of SO₄^2- emission here. Meanwhile, the average ratio of NO₃-/EC and SO₄^2--/EC indicated secondary oxidations were the main reasons for SO₄²⁺ and NO₃-. For the elements, S, K, Ca, Fe, and Cl were the abundant elements. As exceed the WHO guidelines limit and the cancer risks of As displayed possible health impact for people here. PAHs also showed high pollution levels, with an average of 166.6 ng/m³ in ambient air, and 108.0 ng/m³ in household. Coal combustion, biomass burning and vehicle emission were still the main sources. The ILCR for all age groups were higher than 1×10^-6, displayed that possible risks of PAHs were existed here, and PAHs pollution in this community need to be concerned.

Keywords: indoor air, office and household, cooking, characteristics, Health risk