Updated: June 29, 2020 9:34:54 pm
Written by Sagnik Dey and Joshua Apte
The unprecedented COVID pandemic has forced countries to shut down most economic activities and send the citizens into a lockdown. India started the first phase of lockdown from March 24 to April 14, followed by a second (April 15-May 3), third (May 4- May 15) and fourth (May 16-May 31) phase with varying degrees of relaxation. This social disruption came at a time when India had embarked on a mission to improve its air quality and alleviate the staggering health and economic burden attributed to air pollution. The lockdown has temporarily halted all activities under the National Clean Air Programme (NCAP), but at the same time provided an opportunity for scientists and policymakers to utilise this situation for learning valuable lessons about changes in air quality and use the knowledge to strategise the future course of action.
Air quality has improved, but not enough. Data from the Central Pollution Control Board monitors across the country show a dramatic improvement in air quality during the lockdown period. Stories about “blue sky” experienced after decades have been going around. While this improvement is no doubt a silver lining in this torrid time, we should not be complacent. We must realise that although air quality has improved, it did not remain below the national standard throughout the lockdown period and certainly never went even closer to the WHO air quality guideline (AQG) in most of the cities. In north India, the level of particulate matter (PM) is usually six to ten times the WHO AQG (two-three times the national standard), and hence, a few days of respite is not just enough for any considerable health benefit.
Second, not all air pollutants have decreased during the lockdown. Ozone, for example, has increased in many cities during the lockdown, suggesting that the benefit of lower particulate pollution level may have been partially compensated by the rise in ozone exposure. One of the authors of this piece has been working with IIT-Delhi and the University of Texas to continuously monitor the individual components that make up particulate matter. This data shows that the largest reduction occurred for black carbon, nitrate and sulphate (secondary particulates formed from precursor gases NO2 and SO2, emitted mostly by vehicles, industries and power plants). However, the single largest component of PM in Delhi, organic aerosol, did not reduce drastically. As a result, the PM did not remain below the national standard consistently.
Addressing only local emission sources is not adequate. Analysis of satellite data and the sensor network has revealed that the reduction of PM level is much higher in urban areas (where all the CPCB ground-based monitoring is carried out) than in the rural areas. Nearly 50-80 per cent of the outdoor air pollution in rural areas is contributed by household emissions and background dust and the rest is transported urban pollution.
During the lockdown, emissions from transportation, construction and industrial (including brick kilns) sectors have almost stopped and those from power plants reduced significantly. However, the emissions from household activities has continued. Also, satellite data reveals open fires during the post-harvesting season in many parts of the country. The consequence of this is unsatisfactory air quality in many rural areas during the lockdown period. With the urban areas usually getting media attention for poor air quality, we often forget that addressing local emission sources in the urban centres is not sufficient to achieve the national standard at a regional scale.
Evidence is emerging that air pollution may enhance COVID transmission risk. Recent studies have shown that patients with non-communicable diseases (for example, chronic obstructive pulmonary disease, cardiovascular disease, hypertension and diabetes) are more vulnerable to COVID infection and fatality. The burden of non-communicable diseases is higher amongst the population exposed to a high level of air pollution making them more vulnerable to COVID. Several early studies have found a positive association between air pollution exposure and COVID transmission risk in various countries. Though more in-depth studies are required to understand the causal pathway, there is no denying that the Indian population, exposed to a high level of air pollution throughout the year, is highly vulnerable. As the lockdown is being lifted to revive the failing economy, air pollution is bound to rise. It is therefore important for India to maintain clean air to minimise the risks of COVID infections in the coming days and months.
After years of deliberation and debate, India has initiated disease burden studies to estimate the health impacts of air pollution (and other major health risk factors) systematically, followed by the launch of NCAP. Although the focus of NCAP is on polluted cities, it is an important step forward as it acknowledges air pollution as a national problem. Recent air pollution mitigation efforts have paid dividends as Delhi experienced a higher number of good days in 2019 as compared to 2017 and 2018. In the post-COVID era, the urgency of reviving the economy must not sideline the NCAP implementation plan. The key mitigation measures such as transitioning to cleaner fuel for household use (through PMUY) that would eradicate household emissions, switching to Bharat Stage VI vehicles and fuels, strict compliance for industrial, power plant and brick kiln emissions, and a sustained programme to stop open crop-waste burning are expected to reduce greenhouse gas emissions and thereby provide opportunities for climate co-benefits.
India is standing at a crossroads, where it could lead the world in battling air pollution and climate change simultaneously, or it could continue ignoring the threat of air pollution now at the expense of our future generations. It is up to all of us to make the right choice.
(Dey is coordinator of Centre for Excellence for Research on Clean Air (CERCA) at IIT Delhi and Apte is assistant professor at the University of Berkeley, California. Views expressed are personal)
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