Lockdowns expose India’s elusive baseline air quality levels

While findings underline an urgent need for a national emissions inventory, progress on the National Clean Air Plan remains low priority

India is warily emerging from lockdowns imposed in several states to tackle the second wave of the deadly COVID-19 pandemic. While the virus devastated India’s healthcare, far more than the first wave last year, many researchers studying India’s air pollution scourge see the stark drop in economic and human activity during the lockdowns as a rare chance to explore the background dynamics influencing India’s air pollution patterns.

The total lockdown of 2020 brought down the particulate matter PM 2.5 to safe levels. In 2021 though, even with limited business activity during the partial lockdowns instated in several parts of the country during April and May, PM levels were back to pre-COVID concentrations.

This has triggered several questions among scientists who say India has enough laws but lacks a comprehensive inventory of emissions that could push greater compliance. Some even believe the country should revise its national ambient air quality standards. India permits an annual average of  60 µg/m3 of PM 10 and 40 µg/m3 of PM 2.5— a fairly liberal relaxation over standards issued by the World Health Organization (WHO). 

Plotting the change

As a first step to gauging the impact of lockdowns on air quality in Indian cities, researchers compared the Central Pollution Control Board (CPCB) air quality data for Delhi, Lucknow, Mumbai and Kolkata over the three months of March, April and May in 2019–when there was no lockdown–with corresponding levels in 2020 and 2021.

During March, April and May 2021, an analysis of state data by Climate Trends shows pollution remained above permissible limits in the big cities of Lucknow and Delhi. However, except Mumbai, all cities showed a dip in the average PM 2.5 levels during the three months in 2020. Mumbai’s average concentration of PM 2.5 between March to May in 2019 was 21.6 ug/m3, which increased to 31.3 ug/m3 in 2020 and then to 40.3 ug/m3 — charting a doubling of PM2.5 concentration during the period.

The safe limit for PM 2.5 (particulate matter measuring less than 2.5 microns) as prescribed by the CPCB is 40 ug/m3. “Mumbai being a coastal city has a mixed effect of local meteorology and prevalent conditions of large-scale motions, including that of cyclones. While cyclones such as Tauktae act as a washout/cleaning effect on the atmosphere, slow wind conditions, and favourable conditions of long transport of particulate matters from neighbouring states act as accumulation, suggesting marginal increase of the pollutants,” said professor SK Dhaka, Rajdhani College, Delhi University.

On the other hand, India’s national capital Delhi saw average PM 2.5 concentrations drop for the three months by nearly a third from 95.6 ug/m3 in 2019 to 69 ug/m3 in 2020. This reprieve though was short-lived as the concentration bounced right back to 95 ug/m3 in 2021. This decline and surge could be attributed to the Centre’s Ujjwala scheme of distribution of LPG cylinders. Research points out that in 2010, only 45% people living in Delhi’s slums used LPG cylinders and the rest depended on biofuels. In 2018, 96% of Delhi slum dwellers got access to LPG through the  Ujjwala scheme, which significantly brought down the biofuel emissions by 64%. But by 2021, the scheme had fallen into disuse as people could not refill their cylinders without aid and they switched back to burning biofuels. That may be one of the reasons for the rise in PM 2.5 levels in 2021.

Similarly, Kolkata’s PM2.5 concentration swayed from 41.8 ug/m3 in 2019 to 27.9 ug/m3 in 2020 and 37.3 ug/m3 in 2021. While there was a complete lockdown in 2020, the 2021 lockdown saw high movement of people seeking healthcare facilities due to increased COVID-19 cases and the state elections in West Bengal, which took place at the end of April and beginning of May.

Among the four cities studied, UP’s capital Lucknow was the only one that saw PM 2.5 concentrations decrease consistently in the three months since 2019, although it still remained above permissible limits. Its average PM 2.5 concentration in 2019 for the months of March, April and May was 103 ug/m3, which dipped to 92 ug/m3 in 2020 during lockdown and further to 79.6 ug/m3 in 2021.

Researchers say lockdowns during 2020 and 2021 lowered traffic and fossil fuel consumption. Closure of factories also added to cleaner air, but the levels are still relatively higher this year. GC Kisku, chief scientist at the Environmental Toxicology unit of the CSIR-Indian Institute of Toxicology Research said, “The good thing is that there has been a decreasing trend in PM10 levels from 2017 onwards. However, this year, the observed levels of PM 2.5, PM 10, SO2, and NO2 at all locations were found to be relatively higher as compared with monitoring data of the previous year.” 

The CSIR also recently released a report on the assessment of ambient air quality of Lucknow, which showed that the mean levels of PM10 (127.1 μg/m3) and PM2.5 (64.5 μg/m3) at all the monitoring locations of residential, commercial and industrial areas from April-May 2021 were higher than permissible limits.

Gufran Beig, a senior scientist with the Indian Institute of Tropical Meteorology (IITM), points out that in 2021, PM2.5 levels rose across several cities due to many reasons. Firstly, the lockdown was not complete and small-scale industries were allowed to function. Biofuel emissions, or household emissions, remained high as people cooked burning wood and cow dung. 

In 2020, power demand plummeted, causing steep drops in the operational capacities of several thermal power plants. This, however, was not the case in 2021 during the same period.  

The accidental emergence of baseline level

According to Beig, the drop in economic and human activity during the lockdowns gave an unprecedented view of India’s background air quality. Delhi saw a decline in emission sources of pollutants by nearly 85%–90%, which allowed scientists to offer an experimental estimate of baseline level that they defined as the minimum level reached after lockdown under consistent fair weather conditions of major pollutants, according to Beig.

Scientists said in a megacity like Delhi, where it was virtually impossible to halt all major sources of pollutant emissions in the normal course, the prolonged lockdown provided a unique opportunity to estimate the baseline concentration of various pollutants for the city. 

The baseline level is the level to which the population is chronically exposed and hence greatly relevant to epidemiological research. Some cities may be prone to spikes in pollution levels, but health outcomes heavily depend on chronic exposure.

Permanent concentration of PM2.5: Mumbai more toxic than Delhi

According to research co-authored by Beig and published last year, the maximum share in PM2.5 (41%) and NOx (65%) pre-lockdown was from the transport sectors. The baseline natural levels of the atmosphere for PM2.5 and NO2 are supposed to be permanently present near the surface and remain in equilibrium until a significant external forcing disrupts the equilibrium, and increases or decreases these levels. Scientists have found the level of permanent concentration of PM2.5 to be highest for Mumbai (33± 7 μg/m3) and lowest for Chennai (6 ± 2 μg/m3). The baseline values of NO2 are highest for Delhi (8 ± 3 ppb) and lowest for Kolkata and Chennai (1.7 ± 0.5 ppb).

Interestingly, Beig’s analysis of mortality during the COVID-19 outbreaks revealed that Delhi recorded relatively fewer deaths during the first wave of the pandemic as compared to many cities in India where recorded ambient pollution levels are much lower as compared to Delhi. Analysts said this anomaly could be explained in their findings of baseline concentration.

Although normal ambient pollution level is highest in Delhi (Annual Mean PM2.5 = 100 μg/m3), the baseline level of PM2.5 is much lower in Delhi as compared to Mumbai, Pune, and Ahmedabad. The maximum death count was recorded (at the time of the study in May 2020) in Mumbai where the PM2.5 baseline level is highest (~33 μg/m3). In Delhi, the baseline level is comparatively very low (22μg/m3), as where the death counts (231 around the same period). Delhi’s mortality count is even lower than that of relatively less polluted cities such as Pune or Ahmedabad— a trend that has been traced back to their baseline levels which are higher than that of Delhi (Table 1). 

Scientists postulate there was a significant rise in fatalities among COVID-19 patients with underlying conditions in certain cities because of chronic exposure to baseline air pollution levels rather than averaged ambient air pollution levels for PM2.5. They point out that baseline air pollution levels seriously weaken the immune system. Chronic exposure causes prolonged inflammation, which hyper-activates the innate immune system, making people more vulnerable to infection, illness, and premature death.

According to Dhaka, while the atmosphere was fairly clean in 2020, the condition of 40 ug/m3 prescribed by the CPCB was still not met. “According to a 24-hr baseline emission scenario for Delhi during lockdown, the afternoon levels matched the WHO standards, but because of high humidity early in the morning, the PM 2.5 levels were as high as 100 ug/m3,” Dhaka explains. Particulate matter, after coming in contact with moisture available in the atmosphere, assumes a larger size and concentration. However, since this PM is mostly made up of water it does not make the air dangerous, Dhaka adds. Additionally, dust transportation from Rajasthan in the west can cause fluctuations of up to 50% in PM 2.5 levels. 

Need for a national emissions inventory 

“Household emissions and open fires remain major sources of emissions in north India as they contribute nearly 20-30% more emissions than traffic. In a business-as-usual scenario, pollution is projected to increase and worsen as the population increases. Greater monitoring and reporting has arrested the PM 2.5 trend in the region of Delhi, but in eastern India the trend is increasing,” says Sagnik Dey of Centre of Excellence for Research on Clean Air ( CERCA) at IIT Delhi. 

Most significantly, Dey points out that India does not have a national emission inventory for each sector beyond 2015-16. There’s also no institutional or self-monitoring of emissions of heavy industry as well without which scenario of attaining clean air will remain off limits. To tackle toxic emissions in air, “India also needs inventory for GHG emissions without which it will be hard to identify sources and attain compliance from industry,” he adds.

India’s heavy industry which includes steel, cement and chemicals is yet to have any decarbonisation targets. Experts have opined that while one can cut emissions in power and transport sectors by switching from fossil fuels to renewables it’s not that simple in heavy industry where emissions, termed as process emissions, are generated in the very process of producing cement, steel or chemicals like ammonia.

National Clean Air Plan: An exercise in standing still

Although researchers are gradually finding the missing pieces in India’s air quality equation, there is little to suggest that new findings will find space in India’s air pollution policy any time soon. This much seems clear from the lack of appetite shown at governmental levels to formulate a comprehensive plan of action. According to new analysis from the Legal Initiative for Forest and Environment (LIFE), practically no progress has been made at the central or state levels in formulating individual action plans. Additionally, LIFE’s analysis also found that interventions that have been planned at the national and city levels, as a part of the current National Clean Air Policy (NCAP), are seriously flawed in their approach because it does not consider rural air pollution or local pollution sources.

“Our analysis shows that India is yet to have an action plan to clean up the air. NCAP is a national action plan only in name—it covers less than 5% of the cities, leaves out rural areas and does not focus on the state as a whole. Each and every component of NCAP till date has been a failure—whether it is monitoring, city action plan or state action plan,” says eminent environmental lawyer Ritwick Dutta, who is also the managing trustee at LIFE.

The NCAP agenda had mandated the preparation of “state action plans for control of air pollution” by the 23 states that have non-attainment cities in coordination with the CPCB and the Ministry of Environment, Forest and Climate Change (MoEF&CC). However, RTIs filed by LIFE to probe progress in 17 NCAP states found that none had formulated these plans, the deadline for which was 2020.

The analysis also points out the heavy urban bias in data collection in NCAP’s monitoring efforts in addition to the use of outdated manual monitoring stations rather than the more advanced and efficient Continuous Ambient Air Quality Monitoring (CAAQMS) technology. “Manual monitoring systems record data less frequently and have a higher scope of error and delay. Despite the more efficient CAAQMS technology, the government plans to spend a larger sum of allocated money on the outdated manual monitoring operation,” the report goes on to lament.

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