The severe air pollution in Bangkok (BKK) is an important issue in Thailand. The Bangkok air quality and meteorological data used in this study were collected by the Pollution Control Department of the Ministry of Natural Resources and Environment, Thailand, during 1996–2009. Measurements of hourly air quality and meteorological data were derived from 10 residential and seven roadside sites. Pearson’s chi-square cross tabulation statistics show that the 24-hour mean PM10 concentrations at both roadside and residential sites were to be significantly higher than the Thai National ambient air quality standards (NAAQS) and World Health Organization (WHO) guidelines. The daily 1-hour maximum O3 (O3-1hr) concentration was higher than the Thai NAAQS at both sites. However, the concentrations of 8-hour time-weighting average of CO (CO8hr) were lower than the Thai NAAQS at both sites. The 24-hour average SO2 concentration and the daily 1-hour mean concentration of NO2 were higher than the WHO guidelines, but complied with the Thai NAAQS at both sites. A stepwise multiple linear regression model was used to analyze the significant factors affecting PM10, CO8hr, O3-1hr, NO2, and SO2 levels at both sites, and the results showed a decreased association with meteorological parameters and an increased association with the area studied and seasons. In contrast, O3-1hr levels exhibited a decreased association with the area studied. This study found that traffic emissions are the major factor causing the spatial variation in air pollutants in BKK, Thailand, while the meteorological parameters might be the main factors that affect the temporal variations. Our findings show the heterogeneously spatiotemporal characteristics of air pollution in BKK, and can be used to help mitigate this problem.