A motorist driving through a thick layer of smog, December 17, 2025. | Photo credit: Sushil Kumar Verma
There is no direct correlation between higher levels of air quality index (AQI) and lung diseases, there is no “compelling data” to show such a link, Environment and Climate Change Minister Kirti Vardhan Singh told the Rajya Sabha on Thursday (Dec 18, 2025).
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However, he admitted that air pollution is one of the “trigger factors” of respiratory diseases and associated diseases.
Mr. Singh was responding to a question from BJP MP Laxmikanta Bajpayee, who holds a degree in Ayurveda. He sought to know if the government was “aware” of studies and medical tests linking “long-term dangerous AQI levels” in Delhi/National Capital Region to pulmonary fibrosis and irreversible reduction in lung capacity. He also wanted to know if the lung elasticity of citizens of Delhi/NCR was halved compared to residents in cities with “good” AQI levels; and if the government had some “solution” to save the people of Delhi from pulmonary fibrosis, COPD, emphysema, reduced lung function and ever-decreasing lung elasticity.
Also read | No deaths due to air pollution, Center told Rajya Sabha
However, the minister responded with only one sentence about the absence of a “direct correlation”. In response to a related question from Congress MP Randeep Surjewala, Mr Singh reiterated – as in previous weeks – that there was “no conclusive data” to establish a direct correlation of death “solely” with air pollution and that the health effects of air pollution were a “synergistic manifestation” of dietary habits, work habits, socio-economic status, medical history, immunity and her health status.
However, the minister detailed the government’s steps to tackle air pollution – the establishment of the Commission for Air Quality Management (CAQM) in 2020 and how it issued “95 statutory guidelines” to reduce air pollution in the region. The Supreme Court on Wednesday termed the CAQM’s actions as a “total failure” to curb pollution in Delhi NCR.
There is a large body of medical literature, including studies in India, linking air pollution levels to increased cases of asthma and chronic obstructive pulmonary disease. Historically, epidemiologists have relied on “association studies” to verify correlations between substances and their health effects. For example, Doll and Hill’s landmark studies were among the first to demonstrate a link between smoking and lung cancer. While these relationships are relatively easy to detect from medical data, the impact of air pollution is much more subtle, operates over a longer period of time, and cannot be detected directly. A well-known study in India from 2011 (Air Qual Atmos Health, Siddiqui et al.) compared the lung activity and respiratory disease profile of children in Delhi with their rural counterparts in West Bengal and Uttaranchal (the latter with much cleaner air) to show that a much higher proportion of children in Delhi had noticeable respiratory problems.
Published – 18 Dec 2025 21:31 IST
