The health risks posed by air pollution in the 23 Asian countries sandwiched between Russia and Australia have been analysed together for the first time – and over 3.4 million deaths occurred in this area in 2021, representing 40% of global air pollution deaths. 

These countries include India, Pakistan, Kazakhstan, Thailand, Singapore and Indonesia, excluding East and West Asia, most of which are middle- and high-income countries. 

Air pollution is hitting their economies hard. They lost 4 to 11% of gross domestic product (GDP) in 2019 due to citizens’ exposure to fine particulate matter pollution, PM 2.5.

The report, produced by the Health Effects Institute (HEI) in Boston and the Institute for Health Metrics and Evaluation, presents the latest comprehensive estimates of exposures to the three major air pollutants: PM2.5, nitrogen dioxide (NO2) and ozone.

Number One killer in South Asia

South Asia is the worst off by far. Air pollution is the number one risk factor for death across the region, accounting for 2.7 million deaths, of which 2.1 million are in India alone. 

Forty-one per cent of all non-communicable disease deaths in South Asia have been linked to exposure to air pollution, which increases the risk of heart disease, strokes, lung cancer, chronic lung disease and type 2 diabetes. 

Exposure to ambient PM 2.5 has also been associated with cardiovascular health including increased blood pressure and risk of cardiac arrest in India, Singapore, and Vietnam.

The effect of air pollution on children is particularly concerning. The report reveals several details. For instance, in Central Asia one in four deaths in children under five years of age in 2021 was attributable to air pollution. 

Old technologies, rapid urbanisation

The degrees of pollution and health effects vary between the three regions. But there’s a common theme in the sources of pollution: old technologies and practices, urbanisation particularly a rapid rise in motor vehicles. 

Significant sources of PM 2.5 come from burning fossil fuels in vehicles, power plants and other industrial facilities; burning coal in homes for heating and kitchens burning solid fuels, like wood, coal, dung and agricultural residues, for cooking.

Household air pollution (HAP) in homes with little or no access to clean cooking solutions, resulted in almost 1.8 million deaths in the three regions in 2021, which is more than half the number of deaths. 

In Nepal, exposure to HAP was associated with reductions in child height-for-age and weight-for-age, as well as increased rates of stunted and underweight children. Similarly, in India, exposure to PM 2.5 has been associated with a higher risk of underweight and stunting in children. 

In both South Asia and South East Asia, burning vegetation or agricultural waste has severe health effects. In SE Asia, the slash-and-burn practice leads to increased deaths and illness, especially in the lower-income countries like Myanmar. 

In South Asia, extensive burning of crop stubble severely affects the communities living near the agricultural fields. A study in northern India found that living in a district in the top quintile of fires per day was associated with a threefold higher risk of acute respiratory infections

In Tajikistan and Kazakhstan, coal and other biomass are widely used to heat homes – something that polluted Beijing many years ago until the China government government cracked down. 

NO2 harms children, especially in cities

Nitrogen dioxide is mainly generated through fuel burning in vehicles, power plants, and industrial facilities causing asthma and other respiratory diseases. It is the pollutant that, if you’re in heavy traffic, can irritate the eyes, nose, and throat, potentially causing coughing and shortness of breath. 

In cities across the three regions, burning of fossil fuels, especially in vehicles, is a health risk to children. In Bengaluru, India, average temperature and NO2 levels significantly influenced the number of childhood asthma hospital admissions. 

In Hanoi, Vietnam, an increase in short-term exposure to NO2 increased the number of lower respiratory infections (LRI) hospitalisations among children aged 0–7 years.

However, the highest average levels of NO2 worldwide in 2019 were in Central Asia where the average NO2 exposure is 13.3 μg/m³ (micrograms per cubic metre), significantly higher than the World Health Organization (WHO) guideline of 10. 

NO2 levels rose in all five countries analysed in sharp contrast to the global trend. The blame falls on old vehicles and coal-fired power plants. Across most countries, the average vehicle age is well over 10 years, with some vehicles as old as 20 years. 

Cities including Bishkek (Kyrgyzstan), Ashgabat (Turkmenistan) and Tashkent (Uzbekistan) rank among the cities with the highest annual average NO2 exposures. 

A large review of studies conducted in South East Asia found that the relative risk of childhood asthma increases for every 10 μg/m³ rise in NO2, indicating a higher likelihood of childhood asthma due to NO2.

Vehicles emit super-pollutant

Ground-level (tropospheric) ozone is a super pollutant with a more powerful warming impact than a ton of carbon dioxide (CO2), the biggest cause of global warming. But it is very shortlived with a life span of a few days or weeks. Death rates attributed to ozone are 3-5 times higher in South Asia than the global average. 

Notably, India carries around 50% of the global disease burden from exposure to ozone. In a business-as-usual scenario, this is likely to increase by 2050 to such a level that its health impacts are comparable to PM 2.5. 

Ozone is rising in most countries in line with the global trend, with increasing temperatures caused by global warming a major contributor. 

Ozone is a product of hydrocarbons reacting with nitrogen oxides in the presence of sunlight in higher temperatures. It is a major component of smog and can worsen bronchitis, cause emphysema, a chronic lung disease that damages, triggers asthma and permanently damages lung tissue. 

It can also damage plants by entering the pores in their leaves and burning plant tissue during respiration so rising ozone poses a growing threat to food security. 

Air pollution deaths are higher than COVID

“Bold investment is needed to strengthen technical capabilities and the to bolster the data and technology infrastructure at local and regional scales,” Pallavi Pant, a contributor and HEI’s Head of Global Initiatives, told Health Policy Watch.

Pant points out that interventions to reduce household solid fuel use or transportation emissions have shown promising results in several countries, like India’s Ujjwala scheme to provide free or subsidised cooking gas to poor households. Sustained action on these and other locally important sources including waste burning are needed.

In some countries the death rates from air pollution are worse than during the COVID-19  pandemic. 

The global average of age-standardised death rates attributed to air pollution was 100 deaths per 100,000 people. But in Nepal, it was 242 deaths/100,000. 

In India, it was 201 deaths/100,000. The COVID-19 death rate in 2021, as estimated by the Global Burden of Disease, was 157 deaths/100,000 for India, and the global average was 94/100,000.

Several of the 23 countries have taken some steps to reduce air pollution.  Many have implemented tighter emission controls for vehicles, and others – especially in South East Asia and Central Asia – are cooperating to tackle trans-boundary pollution. This is yet to pick up in South Asia, although the Thimpu initiative, aims for cooperation between India, Pakistan, Bangladesh, Nepal and Bhutan. 

Image Credits: Chetan Bhattacharji.