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Weekly Air Quality in Selected Towns of Sri Lanka (21 – 27 July 2025)
During this week, strong westerly winds continued to flow from the Arabian Sea toward Sri Lanka. This resulted in moderate air pollution levels across most air quality monitoring stations in the country and specially in the western coastal station. The highest Air Quality Index (AQI) of 90 was recorded in Ambalangoda, while the lowest AQI of 27 was observed in Nuwara Eliya.
Summaries for the stations from 21 July to 27 July 2025
Air quality index was:
- Moderate (AQI 51 – 100): Chilaw, Digana, Kurunegala, Mirihana, Ambalangoda, Puttalam, Trincomalee, Anuradhapura, Jaffna, and Battaramulla.
- Good (AQI 0 – 50): Colombo, Nuwara Eliya, and Ambalantota
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
