COVID19 Lockdowns across Southeast Asia improve air quality – but not everywhere

Isabella Suarez and Lauri Myllyvirta

The widespread threat of COVID-19 globally has seen Southeast Asian countries responding with varying degrees of lockdowns and community quarantines. The slowdown in economic and social activity has resulted in an overall reduction in urban emissions and electricity demand. In a region where 7 of the 11 nations are among the top 50 countries with the worst air quality conditions in the world, the abrupt halt to transportation, manufacturing, and business have led to reports of “clear skies” and cleaner air in some of the busiest and most populous cities.

In the large urban cities of Kuala Lumpur, Manila, and Bangkok, nitrogen dioxide (NO2) levels were reduced with transportation and manufacturing activities. In Jakarta, Hanoi, and Singapore, there was little change in fine particulate matter (PM2.5) as much of the pollution comes from power plants, industrial, residential and other sources in surrounding areas. In countries like Laos and Cambodia where lockdowns may have been less stringent as COVID-19 cases remain low, air pollution concentrations were within the range of previous years. 

Such improvements in air quality are anomalies and if left unchecked following the lockdowns, air pollution will return swiftly and the threats to human health and wellbeing linked to it will persist. This is especially concerning as new research links past and current air pollution exposure to increased vulnerability to COVID-19. Long-term exposure to NO2 leads to inflammation of the airways, which can exacerbate symptoms of asthma, chronic obstructive pulmonary disorder and similar respiratory diseases. It has also been found to increase risk for respiratory illness in children (WHO). NO2 is also the main source of nitrate aerosols, which can oxidize to form PM2.5, which poses additional health risk, as exposure to these particles can increase the risk of premature mortality from respiratory and cardiovascular disease (EPA). There is a higher risk in Southeast Asia where fossil fuel-heavy and inefficient energy systems, as well as lax emissions standards for industry, agriculture, and transportation, remain significant contributors to NO2 and PM2.5 in the atmosphere. 

With some of the most optimistic economic growth rates in the world, the region has been experiencing rapid urbanization accompanied by one of the fastest rates of electricity growth, increasing by approximately 6% every year and met mostly by coal – one of the most polluting fuels (IEA). Alongside this growth and expansion, the annual mean levels of ambient air pollution in many of the Southeast Asian countries now often exceed more than 5 times the World Health Organization’s (WHO) limits. This makes air pollution the biggest environmental risk to human health, contributing to chronic respiratory and cardiological disease and illness in addition to around 799,000 deaths in the region annually. Fossil fuel is said to be the cause of more than 150,000 of these premature deaths. Given the stress that health care systems and economies are under because of the pandemic, addressing air pollution must be included in countries’ recovery plans and economic stimulus packages to avoid compounding risks.

Our analysis examined NO2 levels using Sentinel-5P satellite data to identify how the individual lockdown responses to COVID-19 impacted air quality. The images were generated using each nation’s specific lockdown start date, and were compared to the same time period in 2019. Where data was available, we also examined the changes in PM2.5 or PM10. We then looked into which sources may have had the most significant contributions to air quality during the lockdowns. 

Where we saw a significant drop in NO2


On March 18, the Malaysian Prime Minister enacted a 14-day “Movement Control Order” (MCO). Though some manufacturing activity such as rubber trade has resumed due to high demand, the country has greatly limited social and economic activity. Beginning April 1, excursions to buy food, necessities, and medicines were restricted to a 10 kilometers radius from a person’s residence. 

As a result, Malaysia saw some of the most drastic and sustained changes in its NO2; the capital of Kuala Lumpur experienced an approximately 60% reduction from NO2 levels of 2019 while the surrounding Selangor province had a 40% reduction in NO2. In areas where coal and gas power plants are located, NO2 remains relatively unchanged as operations continue. The dramatic reductions in NO2 are mainly a result of transportation restrictions. Automobile emissions are one of the main causes of bad air pollution in Malaysia, where car ownership per person is the third highest in the world. Despite the government’s air quality control measures, the massive number of vehicles on the road are huge contributors to dangerous air pollution. 

The country also saw a decrease in energy consumption due to the decline in demand that usually comes from commercial and industrial activity. Energy demand during MCO was recorded to cover only half of their total installed capacity.

Figure 1: Kuala Lumpur NO2 levels from March 18 to May 5, 2020 (left) and 2019 (right)


The Philippine government announced an enhanced community quarantine (ECQ) for the main island of Luzon on March 15. Travel between provinces has been heavily restricted, and business and industrial activity has been temporarily limited to the essential. 

Air pollution in the Philippines affects 98% of Metro Manila’s 12.8 million population, and has been linked to between 11,000 and 27,000 deaths in 2018 alone. Vehicular sources, exacerbated by heavy traffic and congestion, usually accounts for 65% of air pollution in the country. The lockdown measures saw an approximately 45% reduction in the NO2 levels of Metro Manila, as a result of the slowdown in transport activity and a 40% decline in the country’s power demand due to the hold on manufacturing and business. Many major generators are running on reduced capacity to manage supply. The country is highly dependent on fossil fuels, but air pollution from coal, oil, and gas was attributed to an estimated 27,000 premature deaths per year.

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Figure 2: Manila NO2 levels from March 15 to May 5, 2020 (left) and 2019 (right)

Where we saw some air pollution improvements


Analysts cautioned that a full-fledged lockdown on one of the world’s most trade-dependent economies would have major ramifications – a lockdown was a ‘nuclear option’ that Singapore resisted. Instead, the country doubled down on mass testing and tracking and closure of international travel as early as January 31. All large gatherings were suspended on Feb 10 and a week later, a stay-home notice was announced. A “circuit breaker” that began on April 7 declared that only essential services could remain open.

NO2 decreased by about 30% since the border closures and stay-at-home measures that have impacted major emitting industries, including shipping and petrochemicals. Despite this reduction, NO2 concentrations remain above recommended levels as essential services in transportation and storage like shipping, safety and navigation services, port and terminal operations, and port marine services remain open. Over the Western region of the country, where 4 major gas plants are located and continue generation, high levels of NO2 persist. 

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Figure 3: Singapore NO2 levels from February 10 to May 5, 2020 (left) and 2019 (right)


On March 12, a work-from-home (WFH) mandate was declared in Jakarta. On March 30, the government declared a public health emergency, whereby regional administrations will be able to impose stricter social restrictions, like closing schools, workplaces, and limiting religious gatherings. 

Indonesia has the most dangerous levels of air pollution in the region. On average, 38,000 Indonesians are estimated to die from lower respiratory infections each year – approximately 3,000 to 6,000 of which would be avoided with clean air.  With the WFH in place, Jakarta saw an approximately 40% drop in NO2 levels in comparison to 2019 levels, indicating a dramatic fall in urban emissions as economic and social activities in the city were reduced. However, PM2.5 remained consistent to previous years, confirming previous studies that the city’s ambient air pollution problem is greatly impacted by pollutants from surrounding areas.

In the Banten province where the Suralaya power stations are located, NO2 remains high. A closer look at air masses trajectories arriving in Jakarta when PM2.5 levels peaked at both the U.S. State Department Jakarta Central and South air quality monitoring stations, show that much of the pollution during the episode was carried from the coal into the city. 

Figure 4: Greater Jakarta and Banten region NO2 levels from March 12 to May 5, 2020 (left) and 2019 (right)


Thailand restricted large gatherings and closed down various public spaces in early March, even prior to closing its borders on March 22, and issuing a State of Emergency on March 26. These measures have not resulted in dramatic changes in PM10 or NO2, as the north of the country has been dealing with forest fires caused by a combination of the land burning for commercial crops and persistent dry conditions exacerbated by climate change. PM10 in Chiang Mai has been increasing since the beginning of the year, due to agricultural burning and forest fires. 

On the other hand, the social distancing measures in Bangkok saw PM10 concentrations decrease in late March to the lowest levels since 2017. Similarly, Bangkok’s NO2 levels decreased by approximately 20% due to less urban transportation. 

NO2 over Thailand’s coal and gas power plants remains at its usual levels. This will likely continue to be the case as the country is set to slash its imports of electricity, as it’s faced with an oversupply of domestic power due to a steep decline in demand. 

Figure 5: Bangkok NO2 levels from March 26 to May 5, 2020 (left) and 2019 (right)

Where we saw sustained air pollution levels


Among the earliest to respond in the region, the Vietnamese government placed the entire province of Vinh Phuc, north of Hanoi, under quarantine as early as February 13. Prime Minister Phuc later issued a directive that placed the entire nation under lockdown effective April 1, though these measures were limited and have since eased as the number of cases in the country has plateaued.

The lockdown did not drastically reduce PM2.5 levels in the two cities where real-time monitoring data is available. PM2.5 remained above the WHO’s recommended limits and within the range of previous years. Hanoi’s average PM2.5 level in the period Feb 16 – May 1 was up almost 40% on year, and Ho Chi Minh City’s by 32%.

However, the lockdown did appear to reduced NO2 emissions in Hanoi, with a drop of about 10% year-on-year since mid-February, indicating a modest reduction in local emissions, particularly from transport. However, the striking thing about satellite-based NO2 retrievals in northern Vietnam is that the power plant and industrial clusters to the east and south of Hanoi are far larger emissions sources than Hanoi itself. Consequently, Hanoi’s air pollution largely originates from outside the city. Satellite measurements show significant increases in emissions from coal power and industrial areas in Quang Ninh province, and from the industrial areas in Ninh Binh south of Hanoi, important sources of air pollution in northern Vietnam.

Figure 6: Hanoi NO2 levels from February 13 to May 5, 2020 (left) and 2019 (right)

Ho Chi Minh saw an approximately 15% reduction in local NO2 levels. Just outside of these major cities, air pollution from coal-fired power plants (CFPP) persists. The country has been receiving excess coal from cargoes forced to divert deliveries meant for India, where a strict lockdown has been enforced, which may have inadvertently increased Vietnam’s coal consumption.

The limited to non-existent impact of reduced local traffic emissions on PM2.5 levels highlights that other sectors – residential, power and industrial – are important sources that need to be addressed in order to substantially improve air quality.

Figure 7: Saigon NO2 levels from March 1 to May 5, 2020 (left) and 2019 (right)

No observed improvements

Cambodia, Laos, Myanmar, Timor-Leste and Brunei have not seen an outbreak of COVID-19 cases in their countries. Measures put in place in the last few months have been preventative and have not resulted in changes to air pollution levels that can be attributed to lockdowns. Notably, in Myanmar and Cambodia, a significant increase in NO2 was observed earlier in the year as a result of the agricultural burning season – a major source of air pollution in these countries.


On March 19, schools, entertainment venues, and shopping centers were shut down for 30 days. By March 30, the Laos government issued a national stay-at-home order, and closed provincial borders. The country generally has good air quality due to lower levels of  industrialisation and motorisation and the abundance of hydropower, but this year NO2 increased drastically. This is due to forest fires in the north of the country that saw thousands of hectares of forest burned. Pollution from burning is exacerbated by uncontrolled slash and burn agricultural practices and garbage burning, which contributes not only to the local situation but also to regional air quality.

Figure 8: Northern Laos NO2 levels from March 19 to May 5, 2020 (left) and 2019 (right)


Transportation and fossil fuel production and consumption, as well as manufacturing remain barriers to better air quality. Despite other countries moving away from coal, Southeast Asia has made it a cornerstone of its energy transition at the expense of human health and sustainable development. Without reasonable improvements in mass transport, urbanization has been accompanied by a mass of personal vehicles on the road, worsening traffic and congestion. As countries begin easing their lockdown restrictions, dangerous air quality – both local and regional – will likely return as countries remain heavily reliant on polluting industries and fossil fuel. 

The current pandemic has emphasized the interconnectedness of our systems, exposing many vulnerabilities and gaps in addressing citizens’ needs. Poor air quality is a key threat to the health, the environment and the quality of life of millions of people as countries and their cities deal with COVID-19. 

Air pollution is a manageable issue. The improvements in air quality at this time confirm that it is possible to reduce air pollution if efforts are targeted towards the main sources of the problem. This includes investing in energy and transportation systems in ways that improve both human health and wellbeing, as well as the economy. Integrating energy policy considerations into air quality planning, and investing in renewable energy could help countries meet public health, environment, resilience, and energy goals. Expanding and modernizing transport could support mobility and yield multiple benefits for both individuals and industries, including a reduction in vehicles on the road and decongestion of traffic.

As lockdowns begin to ease in the region and recovery is top of mind, government stimulus packages must proactively invest in green.

References: Oxford Coronavirus Government Response Tracker