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Keywords: pollution, air pollution, air quality, aqi, environmental problems
Seasonal Air Pollution in Thailand
Air Pollution and conversely the Air Quality in Thailand varies seasonally and by geographic area. Smog is a serious problem during the dry / hot season in much of Thailand. Even the southern Islands are not immune, as there are days when smoke from Sumatra travels North to blanket Phuket, though this is much less common than smog in Bangkok, Northern, and Northeastern Thailand.
March is a particularly troublesome month for air pollution, though it can arrive in early February, and stay around through much of May. April is also generally smoggy, with some time off for Songkran and intermittant rainfall. Northern Thailand generally gets the worst of the annual haze.
- The dry season has a lot more haze and is also when a large amount of agricultural burning is taking place, including in neighboring countries which generate cross-border haze (including Cambodia, Laos, and Myanmar).
- Due to the lack of rain (or at least much less common), the air isn't as clean.
- There are air pattern differences that might possibly intensify various sources of air pollution
Year-Round Air Pollution
Year round, especially between rainy periods, air pollution generally exceeds the WHO standars of a AQI 50. Bangkok as a large metropolis is particularly at risk, though these issues take place throughout the country, based on the widespread sources of pollutants, including:
- Industrial pollution (large-scale intesive agribusiness, construction, and the use of fertilizers and pesticides, including paraquat which is still legal in Thailand, several operating and closed mines, manufacturing and use of asbestos, etc.)
- Power generation (coal, diesel plants)
- Transportation pollution (gasoline and especially diesel fuel)
- Widespread trash burning practices
Kinds and Sources of Air Pollution
The main kinds of air pollutants that are tracked publicly, and of which consumers are aware and concerned, are pm10 and pm2.5 which are particulates of a very small size -- 10 and 2.5 micrometers (microns) in diameter, respectively. However, there is a wider range of sizes which are hazardous to animal and plant life, such as tobacco smoke which is from 1 to 0.01 microns in diameter, and soot (especially from diesel emissions) which is 0.1 to 0.01 microns in diameter. Dust itself can be of three sizes: heavy, settling, and suspended atmospheric dust, the heaviest can range in size starting around 1,000 microns in diameter all the way down to 0.001 microns for atmospheric dust. Pollen, mold, bacteria, and viruses are also particulate matter and range in size from 100 to 0.004 microns.
pm10, pm2.5, pm0.1
- Particulates measuring 10 microns in diameter can be anything from pollen, mold spores, bacteria, settling dust, cement dust, and fly ash.
- Particulates measuring 2.5 microns in diameter (fine particles) can have the same sources, though pollen is generally larger than this.
- Particulates measuring 0.1 microns in diameter (ultrafine particles) include viruses, suspended atmospheric dust, smog, tabacco smoke, and soot.
- Particulates smaller than 0.001 microns in diameter are gaseous contaminants rather than particulates.
Diesel exhaust is particularly hazardous, and labelled a group 1 carcinogen with strong evidence supporting this inclusion. Diesel exhaust includes a variety of contaminants including: sulfates and sulfites, carbon dioxide (though less than gasoline engine emissions), nitrogen dioxide, soot (~0.1 micron size), ground-level ozone,
Rain rain, come again
Smaller particles, especially those lessn than 1 micrometer, can stay in the atmosphere for weeks annd are mostly removed by precipitation. Working against this is the tendency of very small particles to coagulate in a few hours until they achieve a diameter of 0.3 micrometers.
Policy Issues Impeding Improvements
- Vehicle emissions could be curbed significantly with more stringent emissions regulations in terms of new vehicles and all registered vehicles, including passenger vehicles as well as larger vehicles used in commercial transportation. Making diesel engines illegal with a sunset date is needed immediately, and a sunset date on diesel fuel (for the vast majority of passenger vehicles).
- The few coal and diesel power plants should have advanced pollution scrubbers mandated
- Government requirements to use agricultural refuse that can be transformed into useful products, e.g., Biochar (which has a compelling use case in pesticide decontamination as well).