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Updated: Dec 20, 2018 12:53 IST

Air pollution exposures in India constitute a major public health threat. To prevent a full-blown national health crisis, our policy conversations and actions need to first acknowledge, and then respond to, the enormity and severity of the problem.

A significant part of the Indian population is exposed to air quality that is considerably worse than nationally and internationally accepted guidelines. What is the nature of this health crisis, how much do we know, and is there enough evidence to act? We need to engage with these questions as we demand action against air pollution.

Impact of air pollution on health in India are severe and prevalent across all states and socio-demographic groups. These impacts, whether estimated through mortality or morbidity rates, or through measuring reduction in life expectancy – are all growing at a significant rate. As a risk factor for disease burden in the country, air pollution is second only to child and maternal malnutrition, and ranks higher than unsafe water and unsanitary conditions – conditions we have long associated with poor health in India.

As the previous article in this series showed, the annual mean ambient levels of PM2.5 are multiple times both Indian and WHO norms. Health-damaging air pollution exposures are an everyday reality for both urban and rural populations in India. And it is not only ambient air pollution. Household air pollution – primarily caused by burning solid fuels such as wood and dung for cooking, has significant health impacts as well, and 56% of India’s population, largely in the rural areas, continues to rely on solid fuels, with the highest numbers in the states of Bihar, Jharkhand and Odisha. The most recent India State-Level Disease Burden estimates, released by an initiative co-ordinated by the Indian Council for Medical Research and the Public Health Foundation of India, and published in The Lancet Planetary Health, show that ambient and household air pollution contributes nearly equally to health impacts.

Also Read | Understanding the curse of air pollution

In 2017, air pollution is estimated to have contributed to one in eight deaths in India for a total of 1.24 million deaths according to estimates published in the Lancet study mentioned above. The impact goes beyond mortality; air pollution significantly reduces quality of life by increasing the incidence of a range of illnesses. Health literature uses a metric called Disability Adjusted Life Years (DALYs), which includes both the years of life lost due to premature death and the number of years lived with less than ideal health. The Lancet study found that air pollution contributed to more than 38 million years of healthy life lost in India.

The impact of air pollution on newborn babies and infants under the age of five years is particularly alarming. According to a recent WHO report, in 2016, 100,000 children under the age of five die annually due to exposure to air pollution – the highest in the world in this age bracket. This number is particularly astonishing, when compared to the overall under 5 years mortality in India in 2016 which stands at just under 10 lakh. Therefore, 10% of Indian children under 5 years are dying due to air pollution, a problem against which we continue to move at a glacial pace.

Air pollution is also emerging as the single largest risk factor for non-communicable diseases. This is especially the case for women. Air pollution is the single largest risk factor for women for chronic respiratory diseases, while for men, smoking and other occupational risks are also important contributory factors. A similar profile is emerging for cardiovascular disease and diabetes.

We are still discovering the scale and range of damage air pollution causes on our health. Cardio-respiratory diseases and lung cancer in adults, and acute lower respiratory infections in children are the more commonly known impacts of air pollution. However, emerging epidemiological research indicate a much wider range of health impacts of air pollution such as on birthweight, child growth and cognitive abilities, obesity and bladder cancer. For instance, recent studies in Tamil Nadu have provided convincing evidence for impacts of ambient and household PM2.5 exposures on birthweight. These impacts are not currently included in the burden of disease estimates, and therefore the totality of impacts of air pollution in India is likely grossly underestimated.

While there are not many epidemiological studies on long-term mortality in low and middle income countries including India, there is evidence that adverse effects of exposure to air pollution seen in other parts of the world are also occurring in India. While further studies are critical for our understanding, we need not wait for these to act, particularly since pollution levels in India are higher than anywhere else. Changes in daily rates of mortality associated with short-term exposure to particulates in India are similar to those reported in multicity studies conducted in China, South Korea, Japan, Europe, and North America. Several Indian studies have contributed to the pool of studies included in meta-analyses for estimating relative risks of Chronic Obstructive Pulmonary Diseases and cataracts in relation to household air pollution exposure. Arguments about lack of India-specific studies of air pollution on health do not hold water.

The evidence we have now sends a loud and clear message – there is a health crisis unfolding in India. Commissioning additional studies on emissions and impacts will undoubtedly help guide future policy actions. But currently available information and knowledge on health effects and exposure attribution to sources is more than sufficient to move us into ‘mission’ mode. Reasons not to make this move, whether political, financial, legal, or technical, while perhaps compelling, pale in comparison to the following reality: we are consciously subjecting the current and future generations to conditions that increase the burden of non-communicable diseases, impact child mortality, reduce life expectancy, impair cognitive skills, adversely impact pregnant women and their unborn children, and create life-long medical dependencies. We can no longer afford a lackadaisical response to a risk factor that is eroding rural and urban health, across every state in India.

Kalpana Balakrishnan is Director, ICMR Center for Advanced Research on Air Quality, Climate and Health, Sri Ramachandra Institute for Higher Education and Research (SRIHER), Chennai. Shibani Ghosh is a Fellow, Centre for Policy Research, New Delhi