Total lockdown, lesser industrial activity, travel restrictions, shutdown of non-essential services, lesser vehicles on the road – measures taken by the Indian government and by governments across the globe to battle the coronavirus have had one immediate effect!

Cities all over India are reporting reduced pollution levels and clearer skies. Data released by the System of Air Quality and Weather Forecasting and Research (SAFAR) shows that nitrogen oxide levels in the atmosphere since March 5, 2020 have fallen by approximately 45 per cent in Mumbai and Pune, and by 50 per cent or so in Ahmedabad, as compared to the levels recorded in 2018 and 2019. On March 22nd, India was put on a one-day-long nationwide curfew in an attempt to flatten the coronavirus curve – it saw the lowest average PM2.5 and PM10 levels on record during this period.

According to the SAFAR, Delhi has recorded an overall air quality index (AQI) of 92, which lies towards the higher end of the ‘satisfactory’ category (AQIs 51 to 100).The AQI, which is maintained by the Central Pollution Control Board (CPCB), recorded a reading of 56 at the monitoring station at the Indira Gandhi International (IGI) Airport, one of the lowest in recent years. Bengaluru, Kolkata, Delhi and Lucknow witnessed a cleaner air as the Air Quality Index (AQI) stayed within two digits. In the financial capital Mumbai, levels were at 90, versus an average of around 153 in March 2019.

A new analysis by Centre for Science and Environment said morning and evening peaks in PM 2.5 (fine, respirable pollution particles) have flattened out. The reduction in NO2 concentrations is even more pronounced because the major source of NO2 emissions are vehicles and industries. Pollution levels remained lower than the capital’s usual standards, also due to the strong winds and unseasonal rainfall in and around Delhi between 23 and 25 March.

A recent statement by the World Meteorological Organization states, “Efforts to control the coronavirus pandemic have reduced economic activity and led to localized improvements in the air quality. But it is too early to assess the implications for concentrations of greenhouse gases, which are responsible for long-term climate change.”

Satellite imagery from the European Space Agency (ESA) shows that this reduction in pollution levels can be seen in many other countries as well. Readings from ESA’s Sentinel-5P satellite reveal that over the past six weeks, levels of nitrogen dioxide (NO2) over cities and industrial clusters in Asia and Europe were markedly lower than in the same period last year.

Images from the ESA Copernicus Sentinel-5P satellite shows a big drop in the levels of nitrogen dioxide in cities such as Paris, Milan and Madrid. Levels of nitrogen dioxide in London, Birmingham, Bristol and Cardiff seem to be at two thirds or even half of where they were before the pandemic.

According to NASA, nitrogen dioxide levels across eastern and central China have been 10-30% lower than normal. Research by the University of York found that air pollution levels in some US cities have dropped to levels lower than the average of the previous five years.

The World Health Organization describes NO2 as “a toxic gas which causes significant inflammation of the airways” at concentrations above 200 micrograms per cubic metre. Pollution particles may also be a vector for pathogens, as well as exacerbating existing health problems. The WHO is now investigating whether airborne pollution particles may be a vector that spreads Covid-19 and makes it more virulent.”

According to an article in The Guardian, “The health damage inflicted on people by long-standing air pollution in cities is likely to increase the death rate from coronavirus infections, experts have said. Dirty air is known to cause lung and heart damage and is responsible for at least 8m early deaths a year. This underlying health damage means respiratory infections, such as coronavirus, may well have a more serious impact on city dwellers and those exposed to toxic fumes, than on others.

However, scientists at the University of Colorado Boulder have also claimed that the rising atmospheric concentrations of carbon dioxide, which is at its highest levels in at least 800,000 years, have not slowed down despite the wide-scale shutdown of cities, extreme social distancing measures and a drastic reduction in transportation usage.