Characteristics of air pollution events: PM2.5
| Autor: | LIU, YEN-YU, 劉晏瑜 |
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| Rok vydání: | 2017 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 105 The frequency, duration and severity of exposure to air pollutants are important factors in exposure assessment. Exposures long – term and extreme air pollution events have been examined widely with respect to their potential effects, but repeated exposures at moderate levels received little attention. The purpose of this study was to establish a method to evaluate characteristics of their air pollution events. Fine particulate matters (PM2.5) between 2006 and 2016 at Nanzih station were obtained from Taiwan Environmental Protection Agency. Hourly monitoring data were converted to running 24-hour average concentrations. The criterial limit (35 µg/m3) was used to screen for air pollution status. Consecutive hours with 24-hour average concentrations above the limit were treated as the same pollution event. For each identified event, the time of first occurrence, total event hours, average and maximum concentrations were recorded. Between 2006 and 2016, the criterial limit was exceeded 54% of the time, and a pollution event last 92 hours on average, with event average concentration ranging between 35.1 and 83.4 µg/m3, which was substantially higher than the regulatory limit. The duration, frequency and severity of the PM2.5 events showed a strong seasonal pattern. The concentration and duration of pollution events were highest in dry season (October to February) and lowest in rainy season (April to August), with transient season (March and September) in between. The seasonal variation were more pronounced in event frequency and duration. A decreasing trend was observed in event duration, average and maximum concentration in the dry season. The regulatory limit (35 µg/m3) for 24-hr average concentration was used for screening air pollution events in this study. The method may also be applied with different screening value for other pollutants to better characterize intermittent air pollutant exposures. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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