Spatial and temporal analysis of Particulate Matter (PM10) in urban-industrial environment during episodic haze events in Malaysia

Haze episode in Malaysia typically takes place during the dry monsoon season. As a result, high concentration of atmospheric particles was recorded primarily brought by transboundary air pollution from the neighbour country. Therefore, this study aims to evaluate and compare the level of particulate matter (PM10) at urban-industrial areas during the episodic haze episodes in Malaysia. Hourly PM10 concentration with the concentration of gaseous air pollutants such as NOx, NO2, SO2, CO and O3 and meteorological parameters (relative humidity, temperature, wind speed) at urban-industrial areas namely Shah Alam (Selangor), Nilai (Negeri Sembilan), Bukit Rambai (Melaka) and Larkin (Johor), during the haze episode in 1997, 2005, 2013 and 2015 were used for analysis. In this study, spatio-temporal and correlation analysis were used to provide an overview of the distribution pattern and examine the relationships between the gaseous air pollutants and meteorological parameters with PM10 concentration. From the descriptive statistics, it was observed that PM10 level for all study areas were skewed to the right (> + 1) indicating occurrences of extreme events. A significant peak of PM10 concentration for each year of haze events were observed to be started in June or during the southwest monsoon to the inter monsoon in October. The occurrence, duration and impact of 1997 haze was detected to be identical to the 2015 haze event that reached its peak in October. From the correlation analysis, PM10 concentration were strongly correlated to the CO concentration (r > 0.5) during High Particulate Event (HPE). Very weak relationship of PM10 level with meteorological parameters (r < 0.3) were observed. Interestingly, O3 level shows very strong correlation with the meteorological parameters during HPE. The findings provide comprehensive evaluation on PM10 level during the historic haze episodes, thus can help the authorities in developing policies and guidelines to effectively monitor and reduce the negative impact of haze events.