The COVID-19 pandemic has had a devastating impact on both lives and livelihoods in India — the virus has claimed 239 lives, the lockdown has reportedly claimed another 20. While there’s not much cause for cheer in what’s being observed all around, a recent briefing released by Climate Trends points to a possible silver lining: a drastic reduction in air pollution.

‘Good-air days’ for many Indian cities

The briefing paper says that over 90 Indian cities showed minimal air pollution since the lockdown.

35 cities ranked “good” on the fourth day of the lockdown.

These levels have been seen for the first time since the AQI was launched in 2014. Delhi, for instance, recorded its best-ever AQI score of 45 on March 26th. Other major cities also recorded significant drops in the level of major air pollutants.

Percentage drop in PM2.5 and NOx levels. Second Week of March – April 6.

A perusal of the National Air Quality database by CPCB suggests the same pattern in most cities.

Chennai’s monitoring stations are an exception. Analysis of air quality data from Chennai by Atmos shows little variation in air pollution before and after the lockdown. In fact, the data shows a spike in PM10 levels during the week of the lockdown.

Data from the only monitoring station in Chennai measuring PM10 levels indicates a spike after lockdown | Source: Nakul Mehta, Atmos – Respirer Living Sciences

This trend, however, does not indicate that Chennai’s pollution levels have somehow increased during the lockdown. Rather, it reveals the pitfalls of relying on insufficient data. The Atmos report explains that there is only one station which can monitor PM10 levels in the city.

The Climate Trends paper says that Chennai’s monitoring stations are recording only background levels of pollution, which exist even without the lockdown, making it hard to measure the impact of the lockdown on air pollution in the city.

Air pollution places Indians at high risk for COVID-19

The paper points out that people living with higher levels of air pollution could be at higher risk from COVID-19, since coronavirus disease is a respiratory disease. Exposure to air pollution puts people suffering from respiratory problems at higher risk for complications and death.

Air pollution caused more deaths in India in a year than COVID-19 has in the world till now. In 2017, air pollution caused an estimated 1.2 million deaths in India and is considered the third-biggest cause of death in the country. India is also home to 14 of the 15 most polluted cities in the world according to WHO.

Air pollution also exposes Indians to another high-risk factor – Type 2 diabetes. Citing a Health Effects Institute (HEI) study, the report says that “type-2 diabetes can be directly attributed to air pollution.” India is home to the second-highest number of diabetes patients in the world, behind China. The paper points out that diabetes is one of the most distinguished co-morbidities amongst COVID-19 related deaths.

The paper also highlights recent studies, which are establishing relationships between health, air pollution and COVID-19.

A study by researchers in Italy claims that the virus affected North Italy more severely because of air pollution. The hypothesis is that the virus can travel on particulate matter, which if true would make Indian cities highly vulnerable.

Another study by Harvard’s TH Chan School of Public Health makes a more alarming claim. It says that an increase of only 1 ug/m3 in PM2.5 levels is associated with a 15% increase in the COVID death rate. It claims that people living in areas of higher pollution levels are far more likely to die from COVID-19.

Air pollution exacerbates the risks associated with COVID-19 to a deadly combination of co-morbidities. While these new studies are yet to be peer-reviewed, the links between air pollution, respiratory illnesses and diabetes are well-documented. Considering the high levels of particulate matter that Indians are exposed to, the recent reduction of air pollution is a more than welcome sign.

Halted transportation, industrial activity and construction makes the difference

The lockdown brought many anthropogenic (human-made) contributors to a halt. This makes it possible to study their impact on air pollution.

For instance, industrial clusters in Gujarat, infamous for being one of the most critically polluted regions in the country, also reported a significant reduction in air pollution. Vapi is ranked as the most polluted industrial area among these. Since the lockdown, Vapi recorded a 79.7% drop in Sulphur Dioxide (SO2) levels according to the paper. It also had one of its best days ever on March 29th with an AQI of just 80, compared to 313 just a couple of weeks before on March 18th.

Daman Ganga river polluted in Vapi, Gujarat. PIC: Bharat Patel

While industrial activity makes the crucial difference in places like Vapi, it is vehicular transportation for cities like Delhi and Mumbai. In just two weeks of lockdown, the Nitrogen Oxide (NOx) levels fell by 50% in Delhi and 60% in Mumbai according to the Climate Trends report.

Vehicles are a major source of pollution. A 2018 study by TERI found that vehicular transportation was responsible for 81% of Delhi’s NOx levels, while also being significant contributors to PM2.5 and PM10 particles.

The briefing identifies three major anthropogenic causes for the reduction in air pollution during the lockdown. “It is due to a steep decline in traffic volumes, construction, and industrial activities,” it says.

“It is clear that air quality can improve in a matter of weeks”

An analysis of the reduction in air pollution during the lockdown reasserts a lot of what has already been well-documented – the correlation between health and air pollution, the main causes of air pollution and India’s vulnerability to them. But it also represents a possibility for what things may look like in the near future.

The report says that “it is clear that the air quality can improve in a matter of weeks. It has been demonstrated inadvertently with the lockdown that by enforcing more informed and stricter rules and regulations, city administrations can achieve the goals set out in the National Clean Air Programme (NCAP).”

With more than 70% of infrastructure in the country yet to be built up till 2030, it stresses the urgent need to move towards cleaner energy and construction policies. One of its key recommendations is a move to electric and zero-emission vehicles.