Colombo Air Quality Index (AQI)
Sri Lanka's capital — Indian Ocean monsoon advantage, tuk-tuk exhaust, waste burning
Sri Lanka's Island Geography Advantage
Colombo is surrounded by the Indian Ocean — clean marine air flows in from multiple directions. This is fundamentally different from inland South Asian cities trapped by the Indo-Gangetic Plain. During the SW monsoon, ocean air directly washes Colombo's coast. Result: Colombo's annual AQI 78 vs Delhi's 155 — half the pollution of India's capital, same region.
Monthly AQI Pattern
Data: Monthly estimates based on IQAir, OpenAQ, and Sri Lanka CEA records.
Colombo's Two Monsoon Air Quality Calendar
- • Rain directly hits Colombo's western coast
- • Ocean winds carry clean marine air inland
- • July is cleanest month — AQI 52
- • Frequent rain showers wash PM from air
- • Best air quality period for outdoor activities
- • NE winds carry drier air from northeast
- • NE monsoon rains fall on the east coast
- • Colombo (west) receives less rain, drier
- • Pollution accumulates on calm days
- • February is worst month — AQI ~92
Colombo Pollutant Breakdown
| Pollutant | Annual Avg | WHO Limit | Primary Source |
|---|---|---|---|
| PM2.5 | 20 μg/m³ | 5 μg/m³ | Three-wheeler tuk-tuks, two-wheelers, waste burning |
| PM10 | 48 μg/m³ | 15 μg/m³ | Construction dust, unpaved roads, open burning |
| NO₂ | ~28 μg/m³ | 10 μg/m³ | Vehicle exhaust, diesel buses, power generation |
| O₃ | ~40 μg/m³ | 60 μg/m³ | Photochemical formation — worse in Feb inter-monsoon |
| SO₂ | ~8 μg/m³ | 40 μg/m³ | Coal power plant at Lakvijaya (250 km north) |
Colombo vs South Asian Cities
| City | Annual AQI | Key Factor |
|---|---|---|
| Dhaka | 175 | Brick kilns + IGP trap |
| Delhi | 155 | IGP geography |
| Lahore | 168 | World's most polluted |
| Kathmandu | 105 | Valley geography |
| Mumbai | 88 | Sea breeze advantage |
| Colombo ◀ | 78 | Island + monsoon advantage |
| Male | 35 | Open ocean, minimal industry |
Health Advisory for Colombo
Colombo is generally safe for outdoor activities. Bring a surgical mask or N95 for heavy traffic corridors (Galle Road, Baseline Road). June–August is the cleanest time to visit.
Run or cycle early morning on the Galle Face waterfront promenade — sea breezes are strongest before 9am. Avoid main roads during peak hours (7–9am, 5–8pm).
February and December are most likely to trigger respiratory symptoms. Keep windows closed on hazy days. Air purifiers recommended for Colombo 3–7 areas near the port.
PM2.5 at 20 μg/m³ creates meaningful long-term health exposure. Consider HEPA air purifier for bedroom. Avoid burning waste in garden — common but a major PM2.5 source.
Colombo Air Quality FAQ
How does the monsoon affect Colombo's air quality?
Colombo sits at the meeting point of two monsoon systems: the Southwest (SW) monsoon (May–September) and Northeast (NE) monsoon (November–March). The SW monsoon is the bigger air quality benefit — it brings heavy rainfall directly to Colombo's western coast, washing particulates from the atmosphere. July is typically the cleanest month, with AQI regularly below 55. The NE monsoon is drier in Colombo (though it rains on the east coast of Sri Lanka) and corresponds to the more polluted months (November–February). Inter-monsoon periods (April and October) have the highest ozone due to strong radiation and calm winds.
What are the main sources of pollution in Colombo?
Colombo's pollution has three dominant sources: (1) Three-wheelers and two-wheelers — Sri Lanka has an extremely high density of motorized three-wheelers (tuk-tuks) and motorcycles, many running on older, poorly maintained two-stroke engines that emit high levels of hydrocarbons and PM2.5; (2) Open waste burning — Sri Lanka's solid waste management system is under-resourced, and open burning of garbage in peri-urban areas is common; (3) Vehicle traffic generally — Colombo has significant road congestion with an aging bus fleet and rapid personal vehicle growth. Construction dust from Sri Lanka's infrastructure boom is an additional seasonal source.
How does Colombo's air quality compare to mainland South Asia?
Colombo has significantly better air quality than major mainland South Asian cities. Delhi averages AQI ~155, Dhaka ~175, Lahore ~168, Mumbai ~88 — versus Colombo's ~78. Island geography is the primary reason: Sri Lanka is surrounded by the Indian Ocean, which provides constant marine airflow. Pollutants cannot accumulate the way they do in the Indo-Gangetic Plain's geographic trap. Additionally, Sri Lanka has lower heavy industry density than India or Pakistan. However, Colombo's PM2.5 of 20 μg/m³ is still 4× the WHO guideline.
Did the Sri Lanka economic crisis worsen air quality?
Yes, the 2022 economic crisis had measurable air quality impacts. Fuel shortages caused: (1) Extended power cuts (up to 13 hours/day at peak), forcing homes and businesses to use backup generators and wood/biomass fires; (2) Reduced fuel availability led to increased use of older, more polluting vehicles; (3) Municipal services including waste collection were disrupted, increasing open burning of garbage. The recovery since late 2022 has generally restored pre-crisis conditions, but the generator use habit persists in many businesses.
When is the best time to visit Colombo for clean air?
June–August is Colombo's cleanest period thanks to the Southwest monsoon. July is typically the lowest AQI month. Be prepared for frequent rain (Colombo averages 233 mm in June) but the air is fresh and clean. Avoid January–March for the best AQI — the NE monsoon brings drier air from the northeast, allowing pollution to accumulate. February is typically the worst month. If visiting between November and April, monitor air quality apps and prioritize indoor activities on hazy days.