Delhi’s air quality is still better than 2019 and 2018, but the margin of improvement is steadily decreasing, suggest CPCB data
Amid the challenges of COVID-19-induced lockdown, the considerable improvement in the city’s air quality gave some solace for Delhiites fighting a contagion from the confines of their homes.
Now, as they step out to bring life back to normal, the air quality is also slipping back to its ‘normal unhealthy levels’, suggests an analysis of Central Pollution Control Board (CPCB) data done by The Hindu.
The air pollution levels in the city saw a sharp decline during the first two of the four phases of lockdown compared to previous years. However, the margin of decline during the rest of the lockdown and unlock phases has reduced comparatively.
Experts say the government will have to make systematic changes and ensure strict implementation of control measures if it wants to sustain the low pollution levels seen during the lockdown.
The analysis of CPCB data shows that the average air quality index (AQI) during each phase of the lockdown and unlock periods between March 25 and July 31 was less than the AQI of the same period in 2019 and 2018.
A lower value of AQI means better air quality. AQI is the weighted average of different pollutants such as particulate matter, nitrogen dioxide (NO2), sulphur dioxide (SO2) and other pollutants.
No ‘very poor’ days
Also, there were no “very poor” or “severe” AQI days between March 25 and July 31, unlike 2019 and 2018 when there were six and seven “very poor” days respectively. In 2018, the AQI was “severe” on three days, according to the analysis.
A study of PM2.5 and NO2 levels by the Centre for Science and Environment, a research and advocacy organisation in Delhi, till May 31 has also shown similar results.
“We had done an analysis of PM2.5 and NO2 levels and found out that both had substantially reduced during lockdown 1 and lockdown 2. But the levels were rising again during lockdown 3 and 4,” said Anumita Roychowdhury, executive director of CSE.
‘Won’t last long’
The low levels of pollution are not expected to last, according to experts and officials.
The average AQI of Delhi during the first lockdown from March 25 to April 14 was 90.2 compared to 208.5 in 2019 and 197.2 in 2018. But by unlock 2, from July 1 to July 31, when there were a lot of relaxations, including vehicular movement, though the AQI was still less — 83.8 as compared to 134 in July 2019 and 103.8 in July 2018 — the difference had reduced significantly.
The lesser value of AQI in July this year as compared to March and April, when the AQI was 128.2 and 109.8 respectively, was also because of the effect of monsoon. Apart from the known sources of pollution, the air quality is also affected by wind speed, rainfall, temperature and other factors.
“Every department has suffered due to COVID-19 pandemic and many projects to fight air pollution have been affected. But things are starting now. We are in talks with IIT-Bombay for building a smog tower,” a Delhi government official said.
What is needed
“During the lockdown, some major sources of pollution such as industries, majority of vehicles and construction activities were restricted. But it is not possible to stop these sources of pollution in the future. So a lot more effort and technology will be needed to sustain the air quality levels seen during the lockdown,” Ms. Roychowdhury said.
Though Delhi has a long-term Comprehensive Action Plan, which has detailed projects and deadlines in different sectors to reduce pollution, it has not been fully implemented. The Capital has made some progress in terms of fighting air pollution such as reducing entry of trucks into the city, banning polluting fuel such as coal and shutting down all coal power plants, but in many other areas it is lagging in measures.
“We need to have a zero emission strategy for transportation. That includes electric vehicles, non-motorised transport and more public transport. Also, industries should move towards cleaner fuel and follow high emission controls,” said Ms. Roychowdhury. “The government should review the plans and targets set before the pandemic and revise it and ensure strict implementation.”