The fifth State of Global Air report shows air pollution is now the second-leading risk factor for death globally, after high blood pressure. Most of the deaths are from non-communicable diseases (NCD). The report has a silver lining about lives saved which shows how there’s been a large drop in the death rate of children

Almost 2,000 children under the age of five die every day because of air pollution, according to the latest State of Global Air (SoGA). Yet, the annual total of 700,000 deaths is a fraction of the 8.1 million lives lost because of air pollution. While there is a silver lining that some progress has been made, SoGA has several messages of concern for governments and citizens, especially parents. 

The report looks at deaths and health impacts caused by three pollutants: fine particulate matter (PM 2.5), household air pollution, and ozone (O3). It also looks at nitrogen dioxide (NO2), which causes childhood asthma, particularly for infants and toddlers. The study underscores how traffic exhaust, a major source of NO2, can make children acutely ill with long-term consequences. 

“Children are particularly susceptible to the health effects of air pollution, especially since their organ systems, including lungs, are still developing. To the extent possible, efforts should focus on reducing children’s exposure to air pollution.

A recent systematic review reported that exposure to traffic-related air pollution could result in asthma onset as well as acute lower-respiratory-tract infections in children,” Dr Pallavi Pant, head of Global Health at Boston’s Health Effects Institute (HEI), told Health Policy Watch. 

The SoGA report is a joint effort by HEI and UNICEF. It is a detailed analysis of recently released data from the Global Burden of Disease study from 2021.

Nine out of 10 deaths are caused by the tiny PM 2.5 particles. These enter the lungs and then the bloodstream, increasing the risks of NCDs in adults like heart disease, stroke, diabetes, lung cancer, and chronic obstructive pulmonary disease (COPD). 

The report exposes climate inequities as developing and low-income nations have the highest number of deaths. It also underscores how PM 2.5, the most-tracked air pollutant, is linked to greenhouse gases which are warming the world. The sources of both are largely the same – burning fossil fuels and biomass, particularly coal-fired power plants and transportation, and wild and farm fires. The most vulnerable populations are disproportionately affected by both climate hazards and polluted air.

India, Nigeria, and Pakistan top list of child air pollution deaths

Of the 700,000 child deaths are due to air pollution, and almost half a million are due to household pollution. The air pollution-linked death rate in children under the age of five in East, West, Central and southern Africa is over 100 times higher than their counterparts in high-income countries. There are two deaths per 100,000 of the population in rich countries, but the death rate in Africa’s children is 210/100,000. 

The highest number of children dying of air pollution is in India, Nigeria and Pakistan. The reason is largely pollution within households burning polluting fuels such as coal/charcoal, wood, animal dung, agricultural residue etc. 

In India over 169,000 children are estimated to have died in 2021 because of air pollution, that is more than one death every four minutes. Nigeria’s toll is over 114,00, and Pakistan’s over 68,000. 

“Despite progress in maternal and child health, every day almost 2,000 children under five years die because of health impacts linked to air pollution,” said UNICEF Deputy Executive Director Kitty van der Heijden.

“Our inaction is having profound effects on the next generation, with lifelong health and well-being impacts. The global urgency is undeniable. It is imperative governments and businesses consider these estimates and locally available data and use it to inform meaningful, child-focused action to reduce air pollution and protect children’s health.”

Globally, air pollution is only second to malnutrition in terms of risk factors for child deaths. The report points out that children are uniquely vulnerable to air pollution. The damage from air pollution can start in the womb with health effects that can last a lifetime. Children inhale more air per kilogramm of body weight and absorb more pollutants relative to adults while their lungs, bodies, and brains are still developing.

Countries with the highest air pollution deaths 

The total number of deaths linked to air pollution was 8.1 million in 2021, which is one out of every eight deaths globally. This is more than any previous year, which indicates that the disease burden of air pollution continues to rise.

The top 10 countries account for about 70% of all global deaths which includes two hundred countries and territories. 

The two countries with the most such deaths by far are China (2,349,332) and India (2,087,016), which is about 4 deaths a minute due to air pollution.

Air pollution is second only to high blood pressure as a global risk factor for death, except in South Asia where air pollution is the biggest cause of death. 

Most of the global deaths – 7.8 million, or nine out of every 10 – are because of PM 2.5 or ambient air pollution. As the report points out, nearly all of the world’s population lives in areas with unhealthy air. Among the key air pollutants that are currently measured, long-term exposure to PM 2.5 is the most consistent and accurate predictor of poor health outcomes across populations. 

Ozone and NO2: Traffic exhaust a threat to humans 

Apart from PM 2.5 and household pollution, the third cause of death the report examines is ozone (O3). Ground-level ozone is not emitted but it is a product of traffic exhaust, in particular nitrogen dioxide, and warmer temperatures in the presence of sunlight. That’s why, for example, during heatwaves, there is a higher level of ozone in place with heavy traffic from where it can travel long distances. It is also a greenhouse gas. 

For humans, O3 increases the risk of both acute and chronic respiratory illnesses such as COPD. The chances of fatalities are higher among those vulnerable, the sick, and the elderly. The report estimates that in 2021, long-term exposure to ozone contributed to an estimated 489,518 deaths globally, including 14,000 ozone-related COPD deaths in the United States, higher than in other high-income countries. 

However, now ozone is also a rising threat in developing nations as well. SoGA notes that countries including India, Nigeria, Pakistan, and Brazil have experienced increases of more than 10% in ambient ozone exposures in the last decade. 

As the table below shows, while the overall number of air pollution deaths has increased since 1990, this has mainly happened because of a rise in PM 2.5 and ozone (which in turn is produced by, among other factors, nitrogen dioxide from burning fossil fuels in vehicles, etc.) Deaths due to household air pollution declined largely thanks to the use of cleaner cooking fuels. 

Traffic triggers childhood asthma

While the current SoGA report has not looked at deaths attributable to nitrogen dioxide (NO2), exposure has been linked to a variety of health effects, including asthma and other respiratory diseases. As with ozone, the highest exposure to NO2 is in countries with high socio-development index, for example, Canada, Japan, and Singapore. But the exposures are declining because of policy actions like switching to more public transport and electric vehicles. 

Traffic is a major source of NO2 and its concentration is typically highest in urban areas, even though there are other sources of the gas such as power plants, industrial units, and agriculture. Pinpointing the traffic patterns and other factors that lead to spikes in NO2 pollution can help cities identify effective ways to control NO2 and reduce exposure.

Some ‘good news’

SoGA has emphasised that there is some “good news.” Since 2000, the death rate linked to children under five has dropped by 53%, due largely to efforts aimed at expanding access to clean energy for cooking, as well as improvements in access to healthcare, nutrition, and better awareness about the harms associated

with exposure to household air pollution. Although the report has not gone into the effects of specific schemes, India, which has the largest number of child deaths, launched the Ujjwala programme to provide cleaner cooking gas to low-income families. 

The reports authors are clear that air quality actions help. In under-served regions like Africa, Latin America, and Asia, steps can include installing air pollution monitoring networks or low-cost sensors, implementing stricter air quality policies, or switching to hybrid or electric vehicles. 

Arsenal of data 

Scientific studies over several decades have established that air pollution is associated with impacts on every major organ system in humans. While earlier ones looked at the more obvious connections with heart and respiratory issues, more recent ones are exploring the link with diseases such as Alzheimer’s and other neurodegenerative diseases. 

Breathing polluted air for months or years can lead to illness and early death from heart and lung diseases and diabetes, and increase the likelihood of adverse birth outcomes including preterm births, stillbirths and miscarriage. SoGA is the latest of several scientific studies that have conclusively demonstrated the vast health and economic benefits of slashing emissions from burning fossil fuels and biomass.

There’s enough in this arsenal of air pollution data for policymakers especially in the worst-hit countries to step up action quickly. Will they?

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