Choking innocence: Air pollution's toll on India's kids

Air pollution remains one of the most pressing global health challenges, disproportionately affecting low- and middle-income countries. Among these nations, India grapples with alarmingly high levels of air pollution, which significantly impacts vulnerable populations, especially children under the age of five.

A recent population-based analysis provides critical insights into the intricate relationship between ambient air pollution, socio-environmental factors, and respiratory health in Indian children under five years old. The paper published in the Lancet Regional Health synthesises the findings of the study and explores the implications for public health interventions and policy.

The burden of air pollution in India

India, home to 18% of the global population, accounts for over 26% of global disability-adjusted life years lost due to air pollution. With a population-weighted mean PM2.5 exposure of 90 µg/m³ in 2019, far exceeding both the World Health Organization’s (WHO) guideline of 5 µg/m³ and India’s national standard of 40 µg/m³, the country’s air quality presents a significant public health challenge.

While urban areas have historically been the focus of air pollution research, rural regions, where the majority of India’s population resides, also experience elevated PM2.5 levels due to widespread agricultural burning and the use of biomass fuels for cooking and heating.

Children: The most vulnerable population

Children under five are particularly susceptible to the adverse effects of air pollution. Their smaller body size, developing organs, and higher respiratory rates make them more vulnerable to inhaling pollutants. Respiratory illnesses, including wheezing, asthma, pneumonia, and other lung diseases, are prevalent among this demographic, significantly contributing to morbidity and mortality rates.

The study design

The study under discussion combined data from India’s National Family Health Survey (NFHS-5, 2019–2021) with NASA’s Global Annual PM2.5 Grids database to assess the impact of air pollution on children’s respiratory health. This retrospective observational study analysed data from 224,214 children under five years old, representing 165,561 families from 29,757 geographic clusters. Using bivariate and multivariable generalised additive models, researchers examined the associations between ambient air pollution, household socio-environmental factors, and respiratory illnesses.

Key Findings

Alarmingly high PM2.5 levels: The median annual PM2.5 level recorded across India was 63.4 µg/m³, with rural areas experiencing slightly higher levels than urban areas. Northeastern regions reported the highest PM2.5 concentrations, driven by rapid urbanisation, vehicular emissions, and biomass burning. Even PM2.5 levels below the national standard of 40 µg/m³ were associated with increased respiratory illness in children, underscoring the inadequacy of existing air quality standards in safeguarding health.

Strong correlation with respiratory illness: Respiratory illness, defined as cough, fever, and rapid breathing, was reported in 3.3% of children surveyed. The study found a monotonic, non-linear relationship between PM2.5 levels and respiratory illness, with the risk of illness increasing significantly even at low pollution levels. The association plateaued at extremely high PM2.5 levels (~100 µg/m³), a phenomenon attributed to potential pollution avoidance behaviors, measurement limitations, or other unmeasured confounding factors.

Socio-environmental determinants: Beyond air pollution, various socio-environmental factors were associated with respiratory illness. Children from poorer households, those exposed to toxic cooking fuels, and those living in homes with substandard sanitation facilities were more likely to suffer from respiratory illnesses. However, the study did not find a significant direct link between household cooking fuel types and respiratory illness, suggesting that the cumulative effect of ambient and household air pollution might be the underlying driver.

Seasonal and geographic variability: The study noted seasonal variations in respiratory illness, with children surveyed during the monsoon season being at higher risk. Geographic disparities were also evident, with the Central and Eastern regions of India reporting higher odds of respiratory illness compared to the Northern region.

Implications for policy and interventions

Strengthening air quality standards: The findings highlight the need for stricter air quality standards in India. Current national standards of 40 µg/m³ for PM2.5 are insufficient to protect public health, particularly vulnerable populations like young children. Reducing PM2.5 levels to the WHO guideline of 5 µg/m³ could yield significant health benefits.

Expanding the scope of pollution mitigation efforts: While urban pollution sources such as vehicular emissions and industrial activities are well-recognised, rural pollution sources, including agricultural burning and biomass fuel usage, must also be addressed. Policies like the National Clean Air Programme, which aims to reduce PM10 and PM2.5 levels by 20–30% by 2024, should incorporate strategies targeting rural pollution sources.

Promoting clean cooking technologies: The widespread use of biomass fuels for cooking remains a major contributor to both household and ambient air pollution. Initiatives such as the Pradhan Mantri Ujjwala Yojana, which subsidises liquefied petroleum gas (LPG) connections for rural households, should be expanded and complemented by behavioral change campaigns to encourage adoption and sustained use of clean cooking technologies.

Enhancing housing and sanitation: Improving housing quality and sanitation facilities can mitigate the impact of socio-environmental determinants of health. Investments in rural infrastructure, including access to piped water and improved sanitation, can reduce respiratory illness and other health risks associated with poor living conditions.

Seasonal and regional targeting: Given the seasonal spikes in respiratory illness during the monsoon season and the geographic variability in pollution levels, interventions should be tailored to address these patterns. For instance, pre-monsoon awareness campaigns and targeted healthcare resources in high-risk regions could help reduce illness rates.

Challenges and limitations

While the study provides robust evidence linking air pollution to respiratory illness in children, several limitations warrant consideration. The retrospective design precludes causal inferences, and the reliance on survey-reported data introduces potential biases.

Conclusion

This comprehensive analysis underscores the urgent need to address air pollution and its socio-environmental determinants to improve child health outcomes in India. Ambient air pollution, even at levels below the national standard, poses a significant threat to children under five, exacerbating respiratory illnesses and contributing to preventable morbidity and mortality.

The study’s findings serve as a clarion call for policymakers, healthcare professionals, and researchers to prioritise air pollution mitigation and child health interventions. With concerted efforts, it is possible to create an environment where every child can breathe clean air and lead a healthier life.