Fine particulate matters or particles with a diameter smaller than 2.5µm (called PM2.5 hereafter) are the primary group of air pollutants in developing countries. Effects of PM2.5 on human health range from damages to the respiratory tract, lung cancers, heart strokes to premature deaths.
PM2.5 created from incomplete burning such as from internal combustion engines, coal-fired facilities to burning agricultural residues. Some PM2.5 created from other precursors such as the chemical reaction of ammonium with nitrous oxides or sulfur dioxide and forms ammonia salts. In the end, compoents of PM2.5 are included carbonaceous origins, sulfate, nitrate, crustal origins, water and few unknown quantities. The ratios are reported to be different between urban and rural sites, dry and raining reasons or different locations on the globe.
A concentration in the ambient air is a temporal state of a mass balance. In this post, I provide correlations of weather parameters to the PM2.5 concentration. The key parameters include wind speed and direction, precipitation, relative humidity and temperature. Climate data was extracted from MERRA-2 products published by NASA. The ground PM2.5 data was downloaded from AirNow measured by FEM stations placed on the Department of States' sites over the globe. This post covers the sites of Hanoi and Ho Chi Minh City, Vietnam.
The author only evaluated relations between each weather input with PM2.5 concentration with a given timestamp. This approach aims at the correlation and not able to build mechanics for the fate-transport mechanism.