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Aided by weather, Sri Lanka’s lockdown leads to decline in air, sea pollution

  • Air pollution in Sri Lanka’s urban areas has decreased by up to 75% during the lockdown imposed in response to the COVID-19 pandemic, while plastic pollution and other forms of marine pollution have decreased by up to 40% along the island’s coastline, authorities say.
  • Experts say meteorological conditions are also a factor, including the monsoonal change in wind direction and lack of rainfall in recent months.
  • But the environmental respite is likely to be temporary, while the lockdown period threatens to see a surge in another type of waste — face masks — washing out to sea and on beaches if no proper waste management mechanisms are introduced.
  • Experts say the tangible improvements in environmental indicators give a glimpse of how effective lifestyle and economic changes can lead to lasting pollution reduction in Sri Lanka.

COLOMBO — The COVID-19 pandemic has sent half the global population into some form of lockdown. Factories have closed, streets and highways lie empty, restaurants no longer serve customers. Sri Lanka, like most other countries, has imposed strict measures to contain the spread of the virus. And like in many other countries, the sweeping halt in activity has had a tangible impact on pollution.

The government imposed an almost total island-wide lockdown from March 20 that lasted throughout April and into May. During that period, air pollution indexes have improved, particularly in urban areas like Colombo, where vehicle exhaust emissions account for most of the pollution.

Monitoring stations run by the Central Environment Authority (CEA) and the National Building Research Organisation (NBRO) recorded a sharp drop in concentrations of small particulate matter (PM2.5 and PM10) after the lockdown compared to a week before it was imposed, aligning with the mobility restrictions and curfews that came into force.

An NBRO monitoring station in the heart of Colombo recorded a 75% drop in PM2.5 and 65% in PM10 levels, including the lowest 24-hour average within 20 years. The air quality index (AQI) tracked by the U.S. Embassy in Colombo shows a similar trend of improved air quality: April 2020 had an overall average AQI of 52.1 in Colombo, 27% lower than April 2019 and 28% lower than April 2018.

Air quality has improved not only compared to previous years but also to previous months. The April AQI measured by the U.S. Embassy was half the level measured in February, highlighting a clear decline in overall emission levels.

“In Sri Lanka, air pollution is mainly concentrated in urban areas, and more than 60% of our urban air pollution is due to vehicular emissions,” said Sarath Premasiri, a senior scientist at the NBRO. Peaks in air pollution correspond to the morning and evening rush hours, so “If vehicle traffic is low, we expect low levels of pollutants,” Premasiri said.

Other major sources of air pollution are industrial activity, mining, coal- and diesel-fired power plants, domestic activity, burning of agricultural residue, and the traditional slash-and-burn farming method known as chena.

“Most industries and commercial enterprises have also stopped their activities, which minimizes wastewater and solid waste generation and reduces methane, H2S, and other related air pollutant emissions,” Premasiri said.

After vehicle emissions, electricity generation and industrial activity are the main sources of air pollution in Sri Lanka. Image by Dennis Mombauer/SLYCAN Trust.
After vehicle emissions, electricity generation and industrial activity are the main sources of air pollution in Sri Lanka. Image by Dennis Mombauer/SLYCAN Trust.

Global trend

A similar trend has played out worldwide, with concentrations of the pollutant nitrogen dioxide (NO2) declining by up to 30% in some regions. 2020 is also set to experience the largest ever annual fall in CO2 emissions, surpassing any previous economic crisis or war.

In the case of Sri Lanka, the lockdown might not be the only factor driving the change. And the change itself could prove fleeting.

“A single-issue explanation doesn’t hold water. There are at least two impacts going on,” said Lareef Zubair of the Sri Lanka-based Foundation for Environment, Climate and Technology (FECT) and the Columbia Water Center at Columbia University in the U.S.

Besides the curfew, he said, “we have seasonal changes in wind direction. If the wind is coming from the north and the Indian subcontinent, it will pick up more pollution on the way and in Sri Lanka. If it comes from the sea, there is no pollution. The curfew coincided with the wind undergoing monsoonal reversal.”

Experts agree that as the lockdown ends and activity begins to ramp up, pollution levels will likely to reach levels close to the previous normal.

“It will depend on what course of action we take,” said Samantha Kumarasena, chief executive officer of the National Cleaner Production Centre (NCPC). “If we realize the importance of this and regulate activities properly, then we can avoid going back to normal.”

Coastal pollution is on the rise in Sri Lanka, with increasing use of plastic generating more waste that accumulates along the coastline, such as on this popular beach in Negombo. Image courtesy of Terney Pradeep Kumara/Marine Environment Protection Authority.

Less marine pollution

Sri Lanka’s lockdown has also seen a decline in marine pollution, according to Terney Pradeep Kumara, general manager of the Marine Environment Protection Authority (MEPA).

“We have observed that plastic pollution on the beaches has gone down by 40% while nitrate and phosphate levels have decreased by 30%,” he said.

Around 80% of marine pollution originates on land, and different types of plastic comprise most of it. Huge garbage patches float on the waves, toxic microplastics are eaten by fish and work their way up the food chain, and chemical pollutants create dead zones with low oxygen and cause algal blooms that can kill fish and contaminate ecosystems.

Pradeep Kumara said more data is needed to draw definite conclusions about the extent to which the lockdown on its own has contributed to the decline in marine pollution. MEPA has a monitoring system in place to collect monthly data on water quality and pollution, but because of the lockdown, only a limited number of stations have been operating, with data coming in from only five districts.

As with air pollution, there are also meteorological factors at work. “The COVID lockdown might be one reason for the reduced pollution,” Pradeep Kumara said, “but it is also because there has been no rain,” which accelerates the washing of land-based waste and pollutants out to sea.

Solid waste pollution threatens coastal ecosystems such as these mangroves in Dikkowita, in southeastern Sri Lanka. Image by Dennis Mombauer/SLYCAN Trust.

Unintended consequences

But even if the lockdown has had a significant contribution in reducing ocean plastic waste, it risks an increase in another kind of waste: the disposable face masks that have become ubiquitous during the pandemic.

“Places like Hong Kong and China have reported increasing numbers of face masks being washed onto beaches,” Pradeep Kumara said, warning Sri Lanka potentially faces the same problem.

“At the moment, Sri Lanka doesn’t have a system to collect these masks separately, and no clear guidelines on how to dispose of them,” he said.

Kumarasena added, “We have this fear that a lot of masks will end up on the beaches. But no one is talking about that.”

The massive impact of the pandemic has overshadowed this issue, but it will eventually have to be addressed, he said. “Collecting and disposing of the masks in an environmentally friendly manner is not so difficult,” Kumarasena said.

“At household level, in the office, or in the market, you can keep some bins or collection points where people can throw them, and then they can be collected and disposed. A simple waste management mechanism can be employed.”

Southern Hambantota Beach looks pristine after a beach cleanup intiative effort with all plastic waste removed. Image courtesy of Terney Pradeep Kumara/Marine Environment Protection Authority.

Learning to live with less

Experts highlight three dimensions to the relationship between the COVID-19 lockdown and environmental pollution in Sri Lanka. First, the lockdown measures have helped reduce air and marine pollution, at least for a limited time. Second, the response measures might themselves cause a fresh wave of waste. And finally, the pandemic offers an opportunity to look at a cleaner, healthier, less polluted world, if only for a brief window of time.

“The lesson to be learned from this is that if we can adopt more sustainable systems, we can have a real impact,” Pradeep Kumara said. Changes in lifestyles and a more circular economy can reduce air pollution, plastic waste and greenhouse gas emissions, he added.

“Is this kind of action possible only when there is a pandemic?” said Zubair from the FECT. “People are very modest when it comes to climate change, but regarding this pandemic, there is no debate.”

“If we can learn proper lessons from the COVID- 19 pandemic situation, we can plan for a sustainable lifestyle without compromising our quality of life,” said the NCPC’s Kumarasena. “We can do quite a lot of things without depending very much on the resource base and while conserving the resources. We can learn how to live with less.”


Dennis Mombauer is a Colombo-based freelance writer and director of research and education for the SLYCAN Trust. He focuses on climate change, conservation, ecosystem-based adaptation, and sustainable urban development, as well as on autism spectrum disorder.

Banner image of a polluted beach in Wellawatta, Sri Lanka, courtesy of Terney Pradeep Kumara/Marine Environment Protection Authority.

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