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Weekly Air Quality in Selected Towns of Sri Lanka (27 Jan – 02 Feb 2025)
From the 27th Jan – 02nd Feb 2025, air quality was unhealthy for sensitive groups (AQI 100-150) in Kurunegala, Colombo, Battaramulla (Pelawatta), Battaramulla (CEA), Gampaha, Ambalantota, Puttalam, Trincomalee and Jaffna. Moderate (AQI 50-100) in Akurana, Nuwara Eliya and Negombo. Good (AQI 0-50) in Digana. Air quality reached “Unhealthy for sensitive groups” levels on January 28th and 29th, with AQI exceeding 183 in Puttalam.
At the beginning of the week (27th), polluted air appeared across the Bay of Bengal and was carried toward Sri Lanka by northerly winds. As a result, most parts of Sri Lanka experienced poor air quality during the first three days of the week. In the middle of the week, Sri Lanka experienced easterly winds originating from the eastern seaward areas instead of northerly winds from the Bay of Bengal. This shift resulted in good air quality across the country.
However, by the end of the week, unhealthy air was again carried toward Sri Lanka by northerly and easterly winds from the Kolkata region. This led to moderate air quality levels in the northern, western, and eastern parts of Sri Lanka. Even with these changes, the Digana area consistently maintained good air quality from January 29th to February 2nd.
Colombo (US Embassy) recorded the highest weekly average AQI of 125. Digana recorded the lowest weekly AQI of 41.
Observed fine particulate measurements by the minute for last week

The AQ variation at a fine temporal scale is shown in Colombo and Pelawatte for last three days. The peak value in Colombo was about 160 and Pelawatte was about 160.
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