Indian annual ambient air quality standard is achievable by completely mitigating emissions from household sources

Abstract

Exposures to ambient and household fine-particulate matter (PM_2.5) together are among the largest single causes of premature mortality in India according to the Global Burden of Disease Studies (GBD). Several recent investigations have estimated that household emissions are the largest contributor to ambient PM_2.5 exposure in the country. Using satellite-derived district-level PM_2.5 exposure and an Eulerian photochemical dispersion model CAMx (Comprehensive Air Quality Model with Extensions), we estimate the benefit in terms of population exposure of mitigating household sources--biomass for cooking, space- and water-heating, and kerosene for lighting. Complete mitigation of emissions from only these household sources would reduce India-wide, population-weighted average annual ambient PM_2.5 exposure by 17.5, 11.9, and 1.3%, respectively. Using GBD methods, this translates into reductions in Indian premature mortality of 6.6, 5.5, and 0.6%. If PM_2.5 emissions from all household sources are completely mitigated, 103 (of 597) additional districts (187 million people) would meet the Indian annual air-quality standard (40 μg m^-3) compared with baseline (2015) when 246 districts (398 million people) met the standard. At 38 μg m^-3, after complete mitigation of household sources, compared with 55.1 μg m^-3 at baseline, the mean annual national population-based concentration would meet the standard, although highly polluted areas, such as Delhi, would remain out of attainment. Our results support expansion of programs designed to promote clean household fuels and rural electrification to achieve improved air quality at regional scales, which also has substantial additional health benefits from directly reducing household air pollution exposures.

Keywords: PM2.5; air pollution; cooking; heating; lighting.

Fig. 1.

Annual ambient PM_2.5 exposure exceedances in India with reference to Indian NAAQS and WHO air-quality guidelines in the baseline year, 2015. Indian NAAQS: 40 µg m⁻³; WHO-IT1: 35 µg m⁻³; WHO-IT2: 25 µg m⁻³; WHO-IT3: 15 µg m⁻³; WHO-AQG: 10 µg m⁻³. Statistics (as inset figures) are shown as percentage of districts in each region exceeding the standard/guidelines.

Fig. 2.

Percentage of ambient PM_2.5 exposure that can be attributed to household PM_2.5 sources at baseline, 2015.

Fig. 3.

Relative contributions (%) of biomass use for (A) solid-fuel cooking, (B) space heating, and (C) water heating and kerosene use for (D) lighting to annual ambient PM_2.5 exposure at the district level at baseline, 2015.

Fig. 4.

(A) Percentage of districts where ambient PM_2.5 exposure exceeds various guidelines before and after mitigation of household emissions. Definition of the scenarios in the y axis are provided in Table 1 and (B) annual PM_2.5 exposure that needs to be further mitigated in each district after complete mitigation of household PM_2.5 to achieve Indian standard in that district.

Fig. 5.

Changes in population-weighted mean ($\pm 1\sigma$ shown by error bars) annual ambient PM_2.5 exposure (Top) and percentage averted premature mortality based (Bottom). The range of baseline PM_2.5 estimate is shaded in the top; the mean value is indicated by the dotted line. The dashed horizontal line in the top represents the Indian NAAQS. See text for details.