Qualité de l’air à Kandy

Is there air pollution in Kandy?

Kandy is a city located in the central province of the island of Sri Lanka. The central province is one of nine different provinces located throughout the country, with Kandy being considered as one of its major cities. It is home to over 125,400 people, as per a census conducted in 2011 (and thus likely to have increased significantly since then, along with vehicle ownership and infrastructure, both elements that add to rising levels of air pollution).

In late May of 2021, a major pollution event occurred off the coast of Colombo, the commercial capital of Sri Lanka, as well as being its largest city and financial hub. Whilst this is a fair distance away from Kandy, it is worth mentioning due to it being one of the worst disasters of its kind in recent history. A ship containing large amounts of chemicals and plastic materials caught fire, leaking vast amounts of toxic effluence, plastic pellets and microscopic plastic beads into the water.

Whilst a large amount of the damage was confined to the sea, surrounding environments and ecosystems, as well as the land (with much of the coast being covered in tons of hazardous material and plastic particles), the smoke that was emitted would have caused considerable damage to any animals or humans that were exposed. However, due to its inland location, Kandy was kept safe from the immediate polluting effects of the smoke clouds, which were cleared away by strong coastal winds. The impact of the environmental fallout as well as trade, commerce and local livelihoods (such as fishing and tourism, already badly hit by the covid-19 outbreak) has yet to be seen.

Kandy itself presented with a US AQI reading of 37 in early June, a few days after the fire on the ship was extinguished. This reading placed Kandy into the ‘good’ air pollution ratings bracket, which is color coded as green, and requires a US AQI reading of anywhere between 0 to 50 to be classified as such.

These various color codes are used throughout the IQAir website on the various air quality maps and graphs, and correspond with the level of pollution currently present. On the US AQI scale, a ‘good’ rating of air pollution is one of the best that can be attained, indicating that the general public would be safe from any ill effects that air pollution can bring, with even vulnerable individuals being able to partake in outdoor activities with impunity, without having to worry about any adverse effects that higher levels of air pollution can bring.

Other readings of US AQI present in late May of 2021 were ones that went up to 53, placing the air quality into the ‘moderate’ ratings bracket for that particular day. This is color coded as yellow, and requires an entry reading of 51 to 100. As can be seen, it was on the lower end of the spectrum, indicating that whilst highly vulnerable individuals may be at risk to some form of respiratory distress, once again the general population would still feel little to no ill effects from this level of pollution.

However, whilst the air quality over this period of time is of a decently clean level, it can be seen from the records that in times past, Kandy has had some months that came in with significantly higher levels of air pollution, and will certainly have more in the future due to the nature of air pollution and the prevalence of its many causes.

How does air pollution build up in Kandy?

In 2020, Kandy came in with a PM2.5 reading of 21.9 μg/m³ as its yearly average. PM2.5 is one of the main pollutants used in the US AQI aggregate, with other pollutants such as PM10, nitrogen dioxide (NO₂), sulfur dioxide (SO₂) and ozone (O₃) being taken into account to get the final US AQI reading.

Whilst PM2.5 makes up a smaller portion of what is being calculated to form this US AQI number, it is also a prominent measure of air pollution in its own right, due to it being one of the more dangerous forms of air pollution present. Its incredibly small size of 2.5 microns or less in diameter gives it the ability to penetrate deep into the lung tissue and cross over into the blood stream, causing all manner of severe ailments and health effects.

This reading of 21.9 μg/m³ placed Kandy in 715^th place out of all cities ranked worldwide in 2020, as well as giving it a ‘moderate’ air pollution rating (which requires a PM2.5 reading of anywhere between 12.1 to 35.4 μg/m³). In order to attain such levels of pollution, various sources of pollution such as vehicular emissions, smoke and fumes from factories, industrial areas and power plants would all add up to form the higher readings on record.

Other sources of air pollution include road dust, fine particles released from the burning of organic matter such as firewood and charcoal, as well as construction sites and road repairs adding to the particle pollution collective.

What are some of the main air pollutants in Kandy?

Other pollutants found in the air in Kandy that go beyond the ones used in the US AQI calculation include ones such as lead and mercury, microscopic rubber particles released from tire treads, as well as volatile organic compounds (VOCs) and black carbon.

These last two are released from the combustion of both fossil fuels and organic matter, and as such would also be prevalent in the atmosphere. Some examples of VOCs include benzene and formaldehyde.

Does Kandy have badly polluted periods of time?

Some of the more highly polluted months on record in Kandy are ones such as January through to March, taken from data collected in 2020. Of note is that all cities currently on record in Sri Lanka also displayed considerably higher readings of air pollution in the first three months of the year.

This is a time period in which the air would be less safe, and as such certain individuals may want to make sure their exposure levels are kept low to avoid the highly negative side effects that excessive pollution exposure can bring.

Does the air quality in Kandy improve over certain times?

After the more polluted time period of the first few months starts to subside, the year of 2020 saw significant improvements from the months of May all the way through to November. Although none of them broke out of the ‘moderate’ pollution ratings bracket and down into the ‘good’ rating, or even better the WHO's target goal of 10 μg/m³ or less, they had PM2.5 readings that went down to numbers that represent a significantly safer quality of air.

Out of all of these months, the one that had the cleanest reading was September, coming in at 13.5 μg/m³. This was seen in many cities throughout Sri Lanka over 2020, seeming to be the month in which the air would be significantly more free from smoke, haze and damaging clouds of particulate matter.