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[MANILA] Lockdowns ordered in South-East Asia and South Asia to contain the spread of COVID-19 have resulted in an unexpected bonus — cleaner streets and reduced air pollution.
Around one third or 2.2 million of the world’s 7 million premature deaths each year from air pollution occur in the WHO’s Western Pacific Region — home to one-quarter of the world’s population.

“Measures related to frequent street cleaning to prevent contamination and bio-organism expansion such as COVID-19 should be maintained, and street solid waste management should be enhanced, especially management methods for waste minimisation following the circular economy theory”

Savitri Garivait, King Mongkut's University of Technology Thonburi

Researchers in Metro Manila and the Bangkok Metropolitan Region have noted that with citizens working from home, there has been a significant decrease in particulate matter smaller than 2.5 microns (PM2.5) emanating from vehicle exhaust that is dangerous to human health.   
According to Savitri Garivait, an associate professor specialising in air pollution at King Mongkut's University of Technology Thonburi, Bangkok, air pollution levels have decreased significantly in Thailand following lockdown orders imposed on all big cities on 22 March. 
Meanwhile, air quality stations in Metro Manila’s most populous city, Quezon City, recorded a decrease in PM2.5 by 80 per cent or more during 16—24 March when enhanced community quarantine was enforced.
“We can definitely see and feel the difference,” Mylene Cayetano, who led the data analysis and is an associate professor at the Institute of Environmental Science and Meteorology at the University of the Philippines Diliman, tells SciDev.Net.
After India, a country of 1.3 billion people, imposed a 21-day total lockdown from 24 March to 15 April, the air had become clear enough for people living in several north Indian cities to see the snow-capped Himalayas in the distance for the first time in decades — something that had become a cherished memory for older generations.  
In the capital city of Delhi, considered among the most polluted cities in the world, the air quality index which regularly hovers around the ‘hazardous—dangerous’ range, suddenly dropped down to ‘healthy’. Indian authorities have now extended the lockdown to 3 May with some relaxations for ‘essential’ activity.
In Kuala Lumpur where air pollution is “not severe” unless there’s a haze or other phenomena, there has been “an improvement”, says Andy Chan, dean of engineering at the University of Nottingham in Malaysia. The amount of PM2.5 is currently around 40—50 micrograms per cubic meter of air compared to the usual 50—70 levels, according to the Air Pollutant Index of Malaysia. Chan attributes this to reduced industrial activity.
These gains are important in the Asia-Pacific region where 92 per cent of the population or some four billion people are exposed to levels of air pollution that pose a “significant risk to their health,” according to the UN Environment Programme.
Apart from improved air quality, the streets are cleaner with fewer people, including vendors of street food and other items, around to generate solid waste.
“To keep them it that way, measures related to frequent street cleaning to prevent contamination and bio-organism expansion such as COVID-19 should be maintained, and street solid waste management should be enhanced, especially management methods for waste minimisation following the circular economy theory,” Garivait tells SciDev.Net. “In addition, measures related to household solid waste should be strengthened to support the ‘work-from-home’ lifestyle.” 
Cayetano predicts that after the lockdowns are lifted air pollution levels will go back from ‘normal—moderate’ at the moment to ‘unhealthy’ in Metro Manila. Meanwhile, other parts of South-East Asia continue to face major air pollution problems despite the lockdowns. For instance, Northern Thailand’s seasonal haze problem has been getting worse as extremely dry conditions common at this time of year increase chances of forest fires both in Thailand and in the neighbouring countries, according to Garivait.
The poor air quality is made worse by farmers burning waste to clear land for the next harvest season. In Malaysia, similar slash-and-burn practices start around June to September. Chan, whose research focuses on transboundary haze, expects the conditions this year to be “quite bad” due to a possible El Niño.

Cayetano and Garivait say that steps can be taken to retain some of the positive air quality gains in Metro Manila and the Bangkok Metropolitan Region. They recommend that car owners avoid unnecessary idling, and open burning particularly solid waste, while adopting policies on long-term emission reduction at source.
This piece was produced by SciDev.Net’s Asia & Pacific desk.