Blogs
Weekly Air Quality in Selected Towns of Sri Lanka (27 October – 02 November 2025)
On 31 October and 1 November 2025, the Western Coastal region (Colombo, Battaramulla to Chilaw) recorded Unhealthy daily AQI levels exceeding 150. The AQI was high on 30 November and 2nd November as well as unhealthy for the vulnerable. The regions in the Western hillslopes including Kandy (Digana and Akurana) and the region of aso reached Unhealthy air quality. Other locations experienced moderate air quality with occasional increases in particulate matter concentrations; air quality across Sri Lanka ranged from “Moderate” to “Unhealthy.”
Regional Wind Transport and Cyclonic Storms
During this period, air pollution was extreme in the Northern Indian Indo-Gangetic Plains downstream of the the Himalayas with AQI exceeding 300. This extreme air pollution was transported to Sri Lanka due to the wind circulation modulation due to the storm in the Arabian sea around 28-31 October. There was a complex interaction of the Arabian sea storm and Cyclone Montha in the Bay of Bengal which may eventually help to bring in cleaner air.
Summary for 27 October – 02 November 2025:
Air Quality Index (AQI) levels:
- Moderate (AQI 51–100): Kurunegala, Colombo-7, Mirihana, Ambalangoda, Ambalantota, Puttalam, Trincomalee, Jaffna, Anuradhapura
- Unhealthy for Sensitive Groups (AQI 101–150): Akurana, Digana, Battaramulla, Chilaw
- Unhealthy (AQI>150): Colombo, Chilaw, Battaramulla.
Observed fine particulate measurements by the hour for the last week.
Air Quality impact on human health
Fine particulate matter (PM 2.5) are generally 2.5 microns and smaller in size. Such particles are inhalable and easily lodges inside the lungs reducing capacity. PM2.5 is a concern for people’s health when levels in the air are high. The levels of risk are shown in the dial shown against the US EPA air quality standards. AQ has a scale that run from 0-500, that tells you how clean or polluted your air is. Each level on the scale corresponds to a different level of health concern.
AIR QUALITY BASICS
Air pollution, a widely- talked and argued topic today has been a primary cause of unforeseen climatic changes, many health problems associated with respiratory diseases and ecosystem damage. Vehicular and industrial emissions, dust, burning of fossil fuels, open burning of garbage waste and natural phenomena such as volcanoes, wildfires and pollen contribute to air pollution. Polluted air consists of both particulate matter of fine dimensions and gaseous matter. The presence of these impurities decreases the pureness of the air we breathe.
AQI
United States Environmental Protection Agency (US EPA) has set up a standard to measure the level of air pollution by the following 5 major air pollutants:
- Ground- level ozone (O3)
- Particle pollution (PM2.5 and PM10)
- Carbon monoxide (CO)
- Sulphur dioxide (SO2)
- Nitrogen dioxide (NO2)
Particulate matter of diameter less than 2.5 micrometers (PM2.5) and diameter less than 10 micrometers (PM10) and gases, ozone, carbon monoxide, sulphur dioxide and nitrogen dioxide have been identified as major air pollutants.
The AQI standard for ozone and particle pollution according to US EPA comprises of six categories. Each category is assigned a specific colour and corresponds to a different level of health concern. As the scale grows the air quality turns from good to extremely unhealthy.
Access to real- time air quality data from laser air quality sensoring instruments operated by FECT is available at www.cleanair.lk
