Air Pollution: India's Silent Lung Disease Crisis

India has a high rate of lung disease due to air pollution. The country's air pollution is caused by industry, transportation, coal power plants, and household solid fuel usage. In 2019, air pollution was responsible for an estimated 36.8 billion economic losses in India, with 36.6% attributed to lung diseases, including COPD, lower respiratory infections, and lung cancer. Lung cancer, in particular, has been increasingly linked to air pollution, and doctors in India are witnessing black deposits on the lungs of children and non-smokers. According to the World Health Organization (WHO), air pollution claims approximately 7 million lives annually worldwide, with India contributing a significant number of these deaths.

Lung cancer

India has been ranked 5th among 118 countries for its poor air quality, with 21 of its cities featuring in a list of the 30 most polluted cities worldwide. The country's average PM2.5 concentration—a measure of the density of fine particulate matter in the air—is 11.6 times the World Health Organization's annual air quality guideline value.

The Air Quality Index (AQI) in India is worsening, which has led to a rise in the mortality rate due to lung cancer. Lung cancer patients are vulnerable to degrading lung capacity and respiratory diseases due to the increase in pollutants in the air. According to the 2020 National Cancer Registry Programme report, 1 in every 6 males and 1 in every 7 females in India had a cumulative risk of developing cancer of any site between the ages of 0 and 74. Lung cancer is now the most common cause of cancer-related deaths in India, and it is also a prominent cause worldwide.

The International Agency for Research on Cancer has classified outdoor air pollution and airborne particulate matter of 2.5 µm or less (PM2.5) as a group 1 carcinogen contributing to human lung cancer. Fine particulate matter has been causatively linked with most premature deaths, and lung cancer is a proven adverse respiratory effect of air pollution. Lung cancer risk models, however, often do not include air pollution, and the estimation of cumulative exposure to air pollution is complex.

In 2019, the concentration of PM2.5 in India's air was so high that it was equivalent to smoking 26 cigarettes. This is particularly concerning because tobacco smoking exacerbates the same set of diseases linked with air pollution. While smoking is still the second leading cause of lung cancer, air pollution is a close third, and it is an even greater concern for non-smokers. The number of estimated attributable lung cancer deaths has increased by nearly 30% since 2007 as smoking has decreased and air pollution has increased.

COPD

India experiences high levels of air pollution, which has been linked to a range of adverse health effects, including respiratory issues. In 2015, more than one million premature deaths in India were attributed to ambient air pollution, and a further one million to household air pollution.

Chronic obstructive pulmonary disease, or COPD, is one of the respiratory diseases that can be caused by air pollution. COPD is a chronic inflammatory lung disease that causes obstructed airflow from the lungs. It is characterised by symptoms such as coughing, mucus production, and shortness of breath. COPD is a significant health issue in India, with a high prevalence of cases. From 1990 to 2016, the crude prevalence of COPD in India increased by 29%, while the age-standardised prevalence declined by 5%. This suggests that the increase in cases is due to India's ageing population.

Air pollution is a leading risk factor for COPD in India. In 2016, more than half of the disability-adjusted life years (DALYs) due to COPD were attributed to air pollution, with 33.6% coming from ambient air pollution and 25.8% from household air pollution. The high levels of air pollution in India, particularly in industrial and urban areas, have been linked to the increased prevalence of COPD. Certain occupations that involve exposure to dust and pollutants, such as street sweeping and working in rice mills, also contribute to a higher risk of COPD.

Other risk factors for COPD in India include tobacco use, which accounted for 25.4% of COPD DALYs in 2016, and occupational risks, which accounted for 16.5%. The impact of these risk factors is influenced by socio-economic status, with lower socio-economic groups experiencing higher rates of COPD. Additionally, a history of respiratory diseases, such as asthma or tuberculosis, can increase the risk of developing COPD.

The economic impact of COPD in India is also significant. The average COPD patient in India spends about 15% of their salary on smoking products and 30% on disease management. The total economic loss attributable to air pollution in India in 2019 was $36.8 billion, of which 21.1% was due to COPD.

To address the burden of COPD in India, there is a need for improved detection and management of the disease. Implementing policies to reduce indoor and outdoor air pollution, such as the National Clean Air Programme (NCAP), is crucial. Additionally, early screening and primary prevention of risk factors through COPD-sensitive health literacy programs can help improve the quality of life for individuals at risk.

Lower respiratory infections

India has been exposed to high levels of ambient and household air pollutants, which have had adverse respiratory effects on its population. Respiratory diseases are a significant contributor to morbidity and premature mortality in India. In 2015, more than one million premature deaths were attributable to ambient air pollution in India, and more than one million additional deaths could be attributed to household air pollution.

Indoor air pollution is a significant risk factor for pneumonia among children. In India, most households use biomass fuels such as wood, straw, shrubs, grass, agricultural crops, and animal dung for cooking and heating. The combustion of these fuels produces harmful pollutants such as carbon monoxide, nitrogen and sulfur oxides, benzene, and polycyclic aromatic hydrocarbons. These pollutants have been linked to adverse respiratory effects, including acute respiratory tract infections, asthma, chronic obstructive pulmonary disease (COPD), and lung cancer.

Particulate matter with a diameter of 2.5 μm or less (PM2.5) has been causatively linked with most premature deaths in India. Exposure to PM2.5 has been estimated using satellite data, ground-level monitoring, and studies conducted in India. Outdoor and indoor air pollution are positively associated with upper and lower respiratory tract infections in children. Viral and bacterial infections can cause severe pathological abnormalities in both the upper and lower respiratory tracts, with the lower airway epithelium being more susceptible to damage.

Lower respiratory tract infections (LRTIs) involve infections of the lung and are associated with symptoms like cough, dyspnea, bronchitis, and pneumonia. Bacteria and viruses cause infections in both the upper and lower respiratory tracts, and upper respiratory infections (URIs) are often followed or accompanied by LRTIs. Children are a susceptible group for respiratory diseases, and indoor air pollution in households can increase their risk of developing respiratory infections.

In India, respiratory infections are a leading cause of neonatal and child mortality, with pneumonia being a common reason for avoidable deaths in children under five. Almost two-thirds of households use biomass fuels for cooking, and about 2.7% of children suffered from acute respiratory infections (ARI) in the two weeks preceding a 2015-2016 survey. Policy interventions are needed to reduce the exposure of indoor air pollution, especially among impoverished groups, by providing cleaner fuels for cooking, such as LPG and electricity.

Heart disease

India has a high rate of lung disease due to air pollution. A 2019 study by the Global Burden of Disease found that 39.5% of pollution-related diseases in India were lung diseases, including COPD, lower respiratory infections, and lung cancer.

Air pollution is a significant issue in India, and it has severe consequences for people's health. While lung disease is a prominent concern, air pollution also increases the risk of heart disease. Studies have shown that air pollution negatively impacts heart rate and rhythm, affecting the heart muscle and leading to potential heart failure. This is particularly concerning for young adults, who are increasingly at risk of cardiovascular issues due to their active social lifestyles and frequent exposure to polluted environments.

In 2019, the Global Burden of Disease study estimated that pollution caused 9 million deaths worldwide, with 61.9% of those being due to cardiovascular disease, including ischemic heart disease and stroke. Air pollution is a critical factor contributing to these cardiovascular issues, and this risk is heightened in middle- and low-income countries like India.

The impact of air pollution on heart disease is influenced by other factors such as smoking and diet. While the background rate of heart disease in India is not exceptionally high by world standards, the absolute impact on public health is significant due to the interplay of these risk factors.

To address the problem of air pollution and its impact on heart disease, urgent attention is required. Educating young adults about the dangers of air pollution and implementing initiatives to reduce exposure are crucial steps. Additionally, controlling air pollution by targeting air quality standards set by the World Health Organization (WHO) can significantly reduce morbidity and mortality in India.

Stroke

India has a high rate of lung disease, with 39.5% of air pollution-related diseases in 2019 being lung diseases, including COPD (22.7%), lower respiratory infections (15.5%), and lung cancer (1.3%). Air pollution is also a contributing factor to other diseases in India, such as ischaemic heart disease, stroke, diabetes, neonatal disorders, and cataracts.

Air pollution is a major public health issue, causing 6.5 million deaths and 167.3 million disability-adjusted life years (DALYs) in 2015. It is one of the top five risk factors for mortality in emerging economies such as India and China.

The association between air pollution and stroke has been widely studied, with evidence suggesting that both short-term and long-term exposure to air pollution increases the risk of stroke. Short-term exposures can trigger cerebrovascular events in susceptible individuals, while long-term exposures can increase the risk of future events. The risk of ischaemic stroke, in particular, is higher after short-term or long-term exposure to air pollution, especially in those with a pre-existing cardiovascular burden, large artery disease, or small vessel disease.

Particulate matter (PM) air pollution, specifically PM2.5, has been linked to an increased risk of stroke. These fine particles can penetrate the alveolar spaces of the lungs and enter the bloodstream, potentially reaching systemic organs. The chemical composition of these particles, including reactive transition metals and organic hydrocarbons, can drive inflammation and oxidative stress, contributing to cerebrovascular disease.

While the association between air pollution and stroke is well-established, proving a direct causal relationship remains challenging. However, the reduction of air pollutant concentrations can significantly reduce the risk of cerebrovascular disease, including stroke. This was evident during the COVID-19 pandemic, when outdoor air pollution levels decreased due to global lockdowns, resulting in a decrease in stroke admissions worldwide.

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