Meeting WHO Air Quality Guidelines Could Save Over 9 Million Lives Annually, Finds Cambridge Study

Air pollution could be responsible for millions of preventable deaths every year, particularly in low- and middle-income countries. A new study by researchers from the University of Cambridge has found that meeting the World Health Organization's (WHO) recommended air quality levels could prevent or postpone more than nine million deaths annually across 136 low- and middle-income countries. The study, published in the journal Environment International, examined the health and economic benefits of reducing exposure to two major pollutants: fine particulate matter (PM2.5) and nitrogen dioxide (NO2).

The researchers found that cleaner air can not only reduce premature deaths but also lower the burden of diseases such as heart disease, stroke, chronic obstructive pulmonary disease (COPD) and dementia. It can also reduce healthcare costs and productivity losses.

What Are WHO's Air Quality Guidelines?

The WHO recommends an annual average concentration of no more than 5 micrograms per cubic metre for PM2.5 and 10 micrograms per cubic metre for nitrogen dioxide.

PM2.5 refers to extremely small particles measuring 2.5 microns or less in diameter. Since they are extremely tiny, they can travel deep into the lungs after being inhaled. These particles can come from vehicle emissions, power plants, industrial activity, construction dust and burning fuels.

NO2, on the other hand, is another important air pollutant and is mainly produced when fossil fuels are burned. Vehicle exhaust, particularly from diesel vehicles, industrial emissions and gas stoves and heaters are its sources.

More Than 9 Million Deaths Could Be Prevented

The researchers analysed air pollution, population and health data from 136 low- and middle-income countries and combined this with existing evidence linking pollution exposure with disease and death.

Their study suggested that bringing PM2.5 concentrations down to the WHO's recommended air quality guideline level could prevent or postpone about 9.4 million deaths every year across the countries studied. Reducing NO2 exposure to the WHO guideline level could prevent or postpone another 1.1 million deaths annually.

The researchers also examined what could happen if countries achieved the WHO's less stringent interim targets. Even this level of improvement could have a major effect, with around 6.6 million fewer deaths linked to PM2.5 and 4,35,000 fewer deaths associated with NO2.

Heart Disease And Stroke

The health benefits of cleaner air would go beyond preventing deaths. The study estimated that meeting WHO's PM2.5 guideline could result in around 2.8 million fewer new cases of COPD, 1.1 million fewer cases of dementia, 7.3 million fewer cases of coronary heart disease and 2.3 million fewer cases of stroke in a year.

This is because air pollution does not affect only the respiratory system. Fine particles can enter the lungs and lead to inflammation and impact processes of the blood vessels and the cardiovascular system. Long-term exposure has been linked to several serious conditions, including coronary heart disease, stroke, asthma, COPD and dementia.

Cleaner Air Could Also Save Money

The study found that achieving WHO air quality targets could have significant economic benefits in addition to the health gains. Researchers estimated that meeting the PM2.5 guideline could result in annual direct medical cost savings of about $11.8 billion for coronary heart disease, $5.9 billion for stroke and $8.6 billion for dementia.

Low- And Middle-Income Countries

The researchers said the burden of air pollution is particularly high in low- and middle-income countries. Rapid urbanisation, economic development and increasing dependence on cars and other motor vehicles have added to the worsening outdoor air quality in many of these countries.

Dr Annalan Navaratnam, Clinical Research Fellow at IMS Epidemiology, University of Cambridge, said tackling air pollution could have a major effect on quality of life and the number of early deaths.

"For the first time, we've been able to model the potential benefits of the WHO's clean air guidelines across countries with the highest levels of outdoor air pollution, both in terms of the millions of lives that could be saved every year and the potential economic and societal benefits," Navaratnam said.

According to the researchers, meeting WHO guidelines will not be easy, particularly in countries experiencing rapid population growth and urbanisation. However, they said decisions related to transport, urban planning and energy could play an important role in improving the air people breathe.

Dr Haneen Khreis from IMS Epidemiology, University of Cambridge, said cleaner air could help countries build healthier populations without sacrificing economic development.

The findings highlight that reducing air pollution is not only an environmental goal. It could also be a major public health measure which can potentially prevent millions of premature deaths and reduce the economic burden of pollution-related diseases every year.

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