Clean air goals can be met by avoiding biomass, says study

Cutting household emissions completely would bring down the national PM 2.5 concentration to 38 micrograms per cubic metre from 55.1 micrograms per cubic metre in 2015.

A study has found that successful implementation of the Pradhan Mantri Ujjwala Yojana (to provide LPG to poor households) and the Deen Dayal Upadhyay Grameen Jyoti Yojana (to provide electricity to all rural households) would help India meet the annual national pollution safe standard for PM 2.5 concentrations.

The study cautions that in a “slow progress” scenario, where clean fuel is not used and only 25% of the household emissions are curbed (Hindustan File Photo)

The challenge is ensuring the beneficiaries use the clean fuels and not switch to using biomass — firewood, dung cakes or agricultural residue — which is heavily polluting.

The household emissions from cooking, space heating, water heating and lighting are responsible for as much as 30% of the annual PM 2.5 exposure, according to modelling studies jointly conducted by scientists from IIT Delhi, University of California, Urban Emissions and University of Illinois at Urbana.

The modelling exercise of curbing household emissions under various scenarios showed that if PM 2.5 emissions from household sources were eliminated completely, 103 additional districts out of a total of 597 districts would meet the national air quality standard of 40 micrograms per cubic metre. In 2015, only 246 districts met the standard. The study, published in Proceedings of the National Academy of Sciences, also found that curbing the use of solid fuels could reduce air pollution-related deaths by 13%, which is equivalent to saving about 2.7 lakh lives a year.

Cutting household emissions completely would bring down the national PM 2.5 concentration to 38 micrograms per cubic metre from 55.1 micrograms per cubic metre in 2015. But in a “moderate progress” scenario, when 75% of all emissions from households are curbed, 72 additional districts will meet the safe standard.

The study cautions that in a “slow progress” scenario, where clean fuel is not used and only 25% of the household emissions are curbed, the average national PM 2.5 concentration will reduce by only 2 micrograms per cubic metre.

At least 7 crore LPG connections have been provided under the Ujjwala Yojana scheme, according to its website. But a report by the Council on Energy, Environment and Water released last November said about 63% of rural households continue to use traditional biomass as their primary fuel for cooking, with some using LPG to supplement their fuel requirements. “Only if all sources of household emissions are stopped, the national PM 2.5 average will come down below 40 micrograms per cubic metre... But these results are under ideal conditions, achieving it is difficult,” said Sagnik Dey, co-author of the study and associate professor at Centre for Atmospheric Sciences, IIT Delhi.

The study also found that even if interventions in household emissions bring down the national average, highly polluted areas such as Delhi would still not meet air-quality standards. In 2015, the average PM2.5 exposure in India is estimated to have been 55 micrograms per cubic metre.

But exposure varies widely across regions, with the highest exposure of more than 100 micrograms per cubic metre observed in Delhi.

“Household fuels are the single biggest source of outdoor air pollution in India,” said Kirk R. Smith, professor of global environmental health at UC Berkeley and director of the Collaborative Clean Air Policy Centre.