Publication Date:
2017-12-13
Description:
Analysis of gaseous criteria pollutants in Bangkok Metropolitan Region (BMR), Thailand, during 2010–2014 reveals that the hourly concentrations of CO, SO2 and NO2 were mostly below the National Ambient Air Quality Standards (NAAQs) of Thailand. However, the hourly concentrations of O3 exceeded the Thailand NAAQs. The maximum concentrations of O3 ranged from 120–190 ppb. On average, the number of hourly O3 exceedances ranged from 1–60 hours a year depending on monitoring station locations. The exceedances occurred during the summer and winter, dry seasons. Interconversion between O3, NO and NO2 indicates crossover points between species occur when the concentration of NOx ([NOx] = [NO]+[NO2]) is ~ 60 ppb. However, when [NOx] 60 ppb. The calculated photochemical reaction rate (the reaction between NO2 with sunlight), during photostationary state ranges from 0.12 to 1.22 min−1. Linear regression analysis between the concentrations of Ox ([Ox ] = [O3]+[NO2]) and NOx provides the role of local and regional contributions to Ox . Both the local and regional Ox contributions enhance the concentration of Ox . Values of the local and regional Ox contributions during non-episode were ~ 44–54 ppb and ~ 0.13[NOx ] to 0.33[NOx ], respectively. Those values were about double during O3 episodes ([O3] 〉 100 ppb). Ratio analysis suggests that the major contributors of primary pollutants over BMR are mobile sources (CO/NOx = 19.8). The Air Quality Index (AQI) for BMR was predominantly between good to moderate. Unhealthy O3 categories were observed during episode conditions in the region.
Electronic ISSN:
1680-7375
Topics:
Geosciences
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