The Air Quality Index (AQI) will be used as a benchmark to determine the kind of official warning that would be issued for the public, said the director-general of the Department of Health, Panpimol Wipulakorn.
The index contains five colour-coded warnings that range from "very good" to "very unhealthy". Each warning is determined by the atmospheric concentration of PM2.5 – micro pollutants so miniscule they can enter the bloodstream through the lungs and cause cardiovascular disease.
A blue warning indicates “very good” air quality, with PM2.5 concentrations of less than 25 microgrammes per cubic metre (µg/m³).
A green warning indicates a “good” PM2.5 reading of between 26-38 µg/m³, while a yellow, or “moderate” warning, reflects a PM2.5 reading of 38-50 µg/m³.
An orange warning indicates air quality that is “unhealthy for sensitive groups”, with PM2.5 concentrations of between 51-90 µg/m³, while a red warning reflects “very unhealthy” conditions, with PM2.5 readings of above 91 51-90 µg/m³.
An orange warning has been issued for Bangkok and its immediate vicinity, as the concentration of PM2.5 exceeded the acceptable standard of 50 µg/m³ for three consecutive days.
The launch of the index follows the level of ultrafine dust particles again exceeding safety standards yesterday in several areas of Bangkok and surrounding provinces, the Pollution Control Department said.
The PCD measured the hazardous PM2.5 particulates in the air at 51-76 microgrammes per cubic metre, exceeding the safety standard of 50 mcgs/cm in 19 areas of Bangkok and its vicinity.
Air quality ranged between moderate and harmful pollution levels.
Ten of the worst affected were in Bangkok and nine in surrounding provinces – Nakhon Pathom, Nonthaburi, Pathum Thani, Samut Prakan and Samut Sakhon.
The PCD urged people to keep abreast of air quality announcements and not to panic. Air pollution would not interfere with their daily activities, the department said.
Children, the elderly, pregnant women and those with chronic disease were advised to be cautious and see a doctor if they experience difficulties.
The department on Monday said people in high-risk areas should avoid outdoor activities or wear N95 rated masks for protection.
Air quality information is available via the department’s website:www.air4thai.pcd.go.th and LINE application, air4thai.