Most urban dwellers wouldn’t know just how bad the air they breathe is, a study evaluating the National Clean Air Programme (NCAP) has revealed.

Most Indian cities lack monitoring stations needed for meaningful air quality assessments, with 215 of 271 cities relying on single-station measurements, researchers have noted in the report.

India needs at least 4,094 continuous air quality monitoring stations under the Central Pollution Control Board’s thumb rules to assess trends in air pollution from tiny particulate matter (PM), but had only 540 continuous and 900 manual stations till December 2023, the researchers said.

The NCAP was launched in 2019. The Union environment ministry released ₹9,650 crore between 2019-20 and 2023-24 for air quality monitoring stations and other actions in 131 cities covered by the NCAP. The programme sought to lower PM concentrations by up to 30 per cent by 2024.

The nationwide counts of monitoring stations have increased nearly four-fold since 2019.

The proportion of the cities that meet PM2.5 standards — PM2.5 refers to particles less than 2.5 microns, small enough to reach the lungs — has increased from 10 per cent in 2019 to 15 per cent in 2023.

The share of cities with PM2.5 concentrations of 120 micrograms per cubic metre or higher — double the national standard of 60 micrograms per cubic metre — classified as “very poor air quality” dropped from 30 per cent in 2019 to 20 per cent in 2023.

However, over half the cities still have PM2.5 concentrations between 60 and 120.

“Cities are implementing various emission control measures to improve air quality, but growing consumption patterns are offsetting these technical gains,” wrote Sarath Guttikunda, adjunct faculty at the Indian Institute of Technology, New Delhi, and founder-director of Urban Emissions, a non-government entity analysing air pollution trends, and his coauthors in their report in the journal Atmospheric Emissions.

Rising vehicle numbers, for instance, have negated gains from new fuel standards that have improved the quality of emissions, while increased waste generation has offset advances in waste management technologies. The number of registered vehicles in the country rose from 300 million in 2019 to 370 million in 2023.

Vehicles ply amid smog in Calcutta. Picture by Pradip Sanyal

The number of cities issuing air quality index (AQI) bulletins has increased 12-fold from 22 in 2015 to 271 in 2023. However, 215 of the 271 cities relied on single-station measurements to calculate their AQI. Only 15 cities calculated the AQI from more than five stations which, the researchers say, is considered an ideal sample size to capture a range of urban locations, such as residential, industrial, traffic, commercial and background areas.

Delhi has over 40 monitoring stations — the highest in the country — but has not recorded significant reductions in its annual average PM2.5 in these years. The observed averages changed from 101 microgram per cubic metre in 2019 to 103 microgram per cubic metre in 2023.

Although urban and environment authorities have initiated multiple actions to lower pollution levels, any gain has been offset by increases in vehicle use, industrial activity and waste burning, the researchers said.

Guttikunda and collaborators Sai Krishna Damamalapati and Gautam Pradhan evaluated air quality trends across Indian cities between 2019 and 2023 using a mix of ground and satellite observations.

They noted what they have described as a “disproportionate emphasis” on lowering PM10 pollution and road dust in cities. While efforts to lower PM10 contribute to improvements in AQI values, they do not translate into overall air quality improvement in cities.

“Trends in regional gaseous pollutant concentrations and national fuel consumption patterns indicate that fossil fuel combustion emissions continue to rise at business-as-usual rates, largely unaffected by these targeted efforts,” the researchers wrote.

A multi-pollutant approach is essential to bring all pollutants, not just PM10 or road dust within standards. Such an approach would be crucial for India’s air quality management where PM2.5 is a key pollutant that often exceeds standards, contributing to illnesses and deaths, they said.