Air pollution second leading risk factor for children, finds new report  

Air pollution has continued to scale new heights to become the second largest killer globally after blood pressure, recording a dubious tally of 8.1 million deaths in 2021. Of this, a staggering 2.6 million deaths occurred in South Asia alone. To this is added debilitating chronic diseases and a range of ill health.

With a population over one billion, India has recorded 2.1 million deaths including 237,000 ozone related deaths.

The bigger shocker is the deeply worrying tally of more than 700,000 deaths among children under five years of age, making air pollution the second leading risk factor after malnutrition globally. As many as 500,000 of these child deaths are linked to household air pollution from cooking indoors using dirty fuels in Africa and Asia.

More than 260,600 of these child deaths were yet again reported in South Asia. The air pollution-linked death rate in children under the age of five in South Asia is 164 deaths/100,000 in contrast to the global average of 108 deaths/100,000. This death tally remains so high despite the 53 per cent drop in death rate since 2000 due to growing access to clean energy for cooking, improved healthcare, nutrition, and awareness. Polluted air is a big trigger for pneumonia and other respiratory infections and allergic diseases in children.

These grim results are from the newly released State of Global Air (SoGA) 2024, a collaborative assessment by the US-based Health Effects Institute (HEI) and Institute for Health Metrics and Evaluation’s Global Burden of Disease (GBD) project. This has been produced for the first time in partnership with UNICEF. These results are linked to the disease burden estimated for the year 2021 in about 200 countries. 

“This new report offers a stark reminder of the significant impacts air pollution has on human health, with far too much of the burden borne by young children, older populations, and low- and middle-income countries,” said Dr. Pallavi Pant, HEI’s Head of Global Health who oversaw the SoGA report release.

Newer risks

While the spotlight of this annual tracker of health impact of air pollution continues to be on PM2.5 and ozone, nitrogen oxides (NO2) has also been added for the first time in this risk assessment. Even though PM2.5 (both ambient and household together) account for more than 90 per cent of the total air pollution disease burden, NO2 and ozone are the growing risk factors globally.

The new spotlight on the exposure to NO2 brings out the importance of the growing risk from traffic exhaust in densely populated urban areas. This is a leading risk factor for the development of childhood asthma. About 55 per cent of 194 countries studied do not yet meet the annual WHO Air Quality Guidelines of 10 µg/m3, resulting in 42 per cent of the world’s population being exposed to unacceptable levels.

The report further points out that in contrast to PM2.5, seven of the 10 countries with the highest NO2 exposures are in the high income countries in West Asia (including Bahrain, Qatar, Kuwait, Lebanon, and the United Arab Emirates). Russia and Turkey also experience high NO2 levels. The highest exposures to NO2 have been noted in countries with high socio-development index, including Singapore, Japan and Canada.

In 2021, exposure to NO2 was linked to 177,000 healthy years of life lost for children and adolescents. There is a strong connection between long-term exposure to traffic-related air pollution and early death due to cardiovascular diseases and lung cancer, asthma onset in children and adults, and acute lower-respiratory-tract infections in children.

NO2 is also a catalyst for formation of ozone, yet another very harmful gas. NO2 reacts with other chemicals in the atmosphere to produce both particulate matter and ozone. According to the report, nearly 490,000 deaths were linked to ozone and countries in West Asia (Qatar, Bahrain, Kuwait, Saudi Arabia, and Iraq), South Asia (Nepal, India, Bangladesh, and Pakistan), and East Asia (Republic of Korea) have reported the highest average ozone exposures in 2020.

Ozone levels have also increased in South Asia. In 2021, ozone was responsible for 56 per cent of all global ozone deaths reported in the region. 

The report further notes that the United States, partly due to its sizable population, widespread ozone pollution and relatively high rates of Chronic obstructive pulmonary disease (COPD), saw 14,000 deaths in 2021, higher than any other high-income country. Since 2010, the overall number of ozone-linked COPD deaths have increased by nearly 20 per cent. This is expected to increase as the population gets older.

Emerging vulnerability of Global South

While South Asia, including India, continues to bear the biggest brunt of particulate pollution-related health impact, the proportion of population experiencing high ozone exposures is also increasing in India, Nigeria, Pakistan, and Brazil. These countries have noted increases of more than 10 per cent in ambient ozone exposures in the last decade.

With populations of over one billion each, India and China have recorded 2.1 million and 2.3 million deaths respectively and together account for nearly 55 per cent of the total global disease burden from particulate matter. In 2021, nearly 50 per cent of all ozone-related COPD deaths were in India, followed by China and Bangladesh.

Evidently, nearly 20 per cent of the global ambient PM2.5 is attributed to household air pollution. This continues to remain a big concern in the Global South even though since 2000, there has been a 61 per cent reduction in the age-standardised death rate from household air pollution. This improvement has been possible due to growing access to clean energy for cooking, grid electricity, cleaner-burning cookstoves, and cleaner fuels.

Spotlight on climate change and air pollution risks

This time, SoGA has highlighted the climate penalty. It notes that the chemical reactions that form ozone increase when the air is warmer, especially during heatwaves. Evidence shows that ozone, also a greenhouse gas, spikes during heatwaves in China and Europe.

Exposure to ozone is associated with an increased risk of both acute and chronic respiratory illnesses such as COPD. Ozone also impacts plants, crop and vegetation. Ozone can reduce crop yields, damage biodiversity, and undermine food security and nutrition. Climate change can exacerbate the health burden of non-communicable diseases, including heart and lung diseases, during heatwaves.

COVID-19 alters order of the ranking of disease

The newly released GBD estimates or GBD 2021, is the first since the COVID-19 pandemic. This shows that COVID-19 has altered the ranking of diseases. During the pre-pandemic phase, 1990 to 2019, the order of the leading global causes of death were ischemic heart disease, stroke, chronic obstructive pulmonary disorder (COPD), and lower respiratory disease. But in 2021, the COVID-19 pandemic changed this order with age-standardised mortality from COVID ranking second after ischemic heart disease, and stroke and COPD dropping to third and fourth place, respectively.

The SoGA report is the lasting reminder of the growing health crisis associated with air pollution and the need to co-join the efforts to cut toxic emissions at source and also the greenhouse has emissions  to maximise the co-benefits of reducing public health risks and the warming impacts.