Over 91% studies link air pollution to adverse health effects in India, finds analysis

More than 91 per cent of epidemiological studies examining the health impacts of air pollution in India have reported at least one adverse health association, according to an analysis released on Friday by the Centre for Research on Energy and Clean Air (CREA).

The analysis reviewed more than 180 studies published between 1975 and 2025, revealing that the health consequences of air pollution extend far beyond respiratory illnesses to cardiovascular diseases, diabetes, pregnancy complications, impaired child growth, tumours, blood disorders and mental and neurocognitive conditions.

CREA, an independent research organisation studying air pollution trends, causes, health impacts and mitigation measures, said the findings highlighted the widespread health risks associated with exposure to polluted air.

𝗥𝘂𝗿𝗮𝗹 𝗮𝗿𝗲𝗮𝘀 𝗮𝗹𝘀𝗼 𝗮𝗳𝗳𝗲𝗰𝘁𝗲𝗱

The analysis found that only 40 of the 180 studies examined the effects of air pollution on rural populations.

Of these, 38 reported at least one adverse health association, indicating that the health burden of air pollution was not confined to major cities.

The findings raised concerns about the relatively limited research attention given to rural communities, despite evidence of significant health risks.

"The findings highlight the need to move beyond a city-centric approach and explicitly include rural areas through a regional, airshed-based approach in the next phase of National Clean Air Programme (NCAP 2.0)," CREA analyst Manoj Kumar said.

An airshed-based approach considers pollution across a wider geographical region rather than treating individual cities as isolated units, recognising that pollutants can travel across administrative boundaries.

𝗗𝗲𝗹𝗵𝗶 𝗱𝗼𝗺𝗶𝗻𝗮𝘁𝗲𝘀 𝗿𝗲𝘀𝗲𝗮𝗿𝗰𝗵

The analysis also revealed substantial geographical disparities in air pollution research across India.

Delhi accounted for the highest number of studies examining the relationship between air pollution and health, with 26 studies focused on the national capital.

Punjab followed with 13 studies, while Maharashtra and Uttar Pradesh accounted for 11 each.

West Bengal featured in 10 studies, Tamil Nadu in nine, Karnataka in eight and Telangana in seven.

The concentration of research in a relatively small number of states highlighted gaps in the geographical coverage of epidemiological studies, particularly in rural and less-studied regions.

𝗠𝘂𝗹𝘁𝗶𝗽𝗹𝗲 𝗽𝗼𝗹𝗹𝘂𝘁𝗮𝗻𝘁𝘀 𝗲𝘅𝗮𝗺𝗶𝗻𝗲𝗱

The reviewed studies investigated several categories of air pollutants, including particulate matter and gaseous pollutants.

Of the studies examined, 45 investigated both particulate matter and gaseous pollutants, while 32 focused on PM2.5.

Four studies examined PM10 alone, and another 16 investigated both PM10 and PM2.5.

Among studies assessing gaseous pollutants, researchers reported statistically significant adverse health associations involving increased mortality, acute respiratory hospitalisations and emergency visits, asthma-related admissions and impaired lung function.

The analysis also highlighted the indirect contribution of gaseous pollutants to particulate pollution.

Sulphur oxides (SOx) and nitrogen oxides (NOx) undergo chemical reactions in the atmosphere, producing sulphate and nitrate particles that contribute to the formation of secondary PM2.5.

These processes mean that controlling particulate pollution requires measures targeting gaseous emissions as well.

𝗖𝗮𝗹𝗹 𝗳𝗼𝗿 𝗯𝗿𝗼𝗮𝗱𝗲𝗿 𝗮𝗰𝘁𝗶𝗼𝗻

CREA called for a multipollutant strategy to reduce exposure to harmful emissions and address the formation of secondary particulate matter and ground-level ozone.

"Air pollution mitigation must adopt a multipollutant approach, addressing gaseous precursors that contribute to secondary PM2.5 and ground-level ozone formation. This requires emission reductions at major sources, including industries, power plants, residential cooking, and other combustion activities," Kumar said.

The organisation stressed that effective pollution control would require coordinated action across sectors and geographical boundaries.

The findings come amid growing concerns over the health burden of air pollution in India, underscoring the need for stronger monitoring, broader epidemiological research and pollution-reduction strategies that protect both urban and rural populations.