| Author: | Zhang, Zhuozhi |
| Title: | Chemical characteristics and health risk assessment of indoor PM2.5 in Chinese residential homes |
| Advisors: | Lee, Shun-cheng (CEE) |
| Degree: | Ph.D. |
| Year: | 2023 |
| Subject: | Indoor air pollution Indoor air pollution -- Health aspects Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Civil and Environmental Engineering |
| Pages: | xxv, 200 pages : color illustrations |
| Language: | English |
| Abstract: | Particulate matters (PM), especially those with smaller sizes, are reported to have posted severe adverse health effects to human through inhalation exposure. Other than widely studied ambient PM pollution, indoor PM pollution which may be present with elevated levels should also be paid more attention to, as people tend to spend most of the time in indoor environments. Spatial variation of indoor PM pollution may not be appropriately concluded due to the differences in sampling schemes and study periods in previous studies, of which mostly the investigations were conducted in a single city. Due to the same reason, the PM inhalation exposure-associated health risks estimated in previous studies varied substantially even with similar levels of concerned PM-bound constituents. To obtain more comparable results for further discussion and analysis, a simultaneous residential indoor sampling campaign was conducted in four Chinese cities, including Hong Kong, Guangzhou, Shanghai, and Xi'an, during winter and early spring of 2016-2017. For indoor PM2.5 levels, an order of Xi'an > Shanghai > Guangzhou > Hong Kong residences was found, which was different from that of outdoors. Compositional analysis results showed that organic matters contributed most fractions in the collected samples, accounting for 33.6-49.9% of the PM2.5 mass. Variations of PM2.5 compositions were identified between cities, while the differences between scenarios with different levels of ambient air qualities or indoor activities were found to be less significant. Traffic-related emission was identified as a major source of indoor PM2.5 commonly found in the investigated four cities, and other city-dependent prominent sources including crustal sources, ocean-going vessel emissions, coal-fired power plants, fuel combustion for heating services, industrial emissions, incineration emissions, etc., were also identified. A probabilistic risk assessment model was adopted for estimating the cancer risks related to the inhalation exposures of PM2.5-bound carcinogenic polycyclic aromatic hydrocarbons (PAHs). With different inhalation rates, body weights, and exposure durations, the cancer risks estimated for different age groups were found of a gradient of adult > adolescent > children > senior, and the cancer risks for male population were generally higher than those of female population. Xi'an residents were found exposed to considerable level of cancer risks as the PM2.5-bound PAHs in Xi'an were found much higher than the other cities, while occupants in other cities were found with insignificant risks associated with inhalation exposures of PM2.5-bound carcinogenic PAHs during winter. High resolution mass spectrometry (HRMS) with high mass resolving power, equipped with soft ionization techniques with less fragmentation has been adopted in analysis of aerosol samples, and non-targeted screening were adopted to assign chemical formulas to the numerous detected species. We further utilized this technique for characterizing the chemical constituents in indoor PM collected during a case study conducted in Hong Kong in early spring of 2021, which were rarely reported in previous studies. 12-hr concurrent indoor and outdoor samples were collected for studying the indoor-outdoor interactions and temporal variations of the PM2.5 and its chemical compositions. Scenarios with different degrees of cooking activities were selected for HRMS analysis. Indoor cooking activities were found contributing more highly oxidized molecules (HOMs) with aliphatic-like structures, as well as large molecules poly-cyclic aromatic core compounds characterized as semi-volatile oxygenated organic aerosols (SV-OOA) constituents. Some highly saturated and less oxygenated aliphatic-like compounds, benzene-core compounds characterized as SV-OOA and biomass burning organic aerosols (BBOA), and a few mono- and poly-cyclic core compounds characterized as hydrocarbon-like organic aerosols (HOA) can be identified separately in samples with cooking activities. |
| Rights: | All rights reserved |
| Access: | open access |
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