Inhalable particulate matter is a health concern, and people living in large cities such as Bangkok are exposed to a high concentration of particulates. This exposure has been linked to respiratory and cardiac diseases and cancers of the lung and brain. The physical and chemical nature of these particles, including size and metal content, may have an important role in their toxicology. Throughout 2018, particulate matter was measured in northern Bangkok covering all three seasons (cool, hot and rainy), near to the Don Muang toll road. PM10 was measured in 24-and 72-hour samples, aerodynamic size and mass distribution were measured for 3-day samples and particle number concentration measured in several locations. A diurnal cycle, with rush hour peaks, was detected in the aerosol number concentration data in February, March and April, but daily variations were high. Roadside measurements showed greater particle number temporal variability than fixed site outdoor measurements from the fifth floor of a building. There was a large fraction of particle number concentration in the submicron range, which showed the greatest variability compared with higher size fractions. PM10 samples varied between 30 and 100 µg m-3, with highest concentrations in the cool season (November to February). Mass samples were analysed for metal and metalloid concentrations via ICP-MS; the largest metal fractions present in the PM10 measurements were calcium, iron and magnesium with average airborne concentrations of 13.2, 3.6 and 2.0 µg m-3 respectively. Copper, zinc, arsenic, selenium, molybdenum, cadmium, antimony, and lead had large non crustal sources, with enrichment factors greater than 100. Principal component analysis identified likely sources as crustal minerals, tailpipe exhaust and non-combustion traffic. Metals associated with combustion sources were most found on the smaller size fraction of particles, which may have implications for associated adverse health outcomes because of the likely location of aerosol deposition in the distal airways of the lung. These particles were the most variable in both time and location.
|Journal||Aerosol and Air Quality Research|
|Publication status||In preparation - 24 Aug 2020|