The latest WHO data: Billions of people still breathe unhealthy air

Almost all of the world's population (99%) breathes more air than WHO's air quality limits, and air pollution is threatening people's health. More than 6,000 cities in 117 countries are monitoring air quality, a record high, but people living in those cities are still inhaling unhealthy levels of fine particulate matter and nitrogen dioxide, with people in low- and middle-income countries most affected.

The findings prompted the World Health Organization to emphasize the importance of limiting the use of fossil fuels and taking other practical steps to reduce air pollution levels.

On the eve of this year's World Health Day, with the theme "Our Planet, Our Health", the 2022 update of the World Health Organization Air Quality Database introduces for the first time earth's surface measurements of the annual average concentration of nitrogen dioxide (NO2). Nitrogen dioxide is a common urban pollutant and a precursor to particulate matter and ozone. The update also includes measuring particulate matter with a diameter equal to or less than 10 microns (PM10) or 2.5 microns (PM2.5). These two categories of pollutants come mainly from human activities related to the burning of fossil fuels.

The new air quality database is by far the most extensive database covering surface air pollution exposure. About 2,000 more cities/human settlements now record surface monitoring data for particulate matter, i.e. PM10 and/or PM2.5, compared to the last update. This marks a nearly 6-fold increase in the number of reports since the database was launched in 2011.

At the same time, the evidence base for the damage caused by air pollution to the human body has been growing rapidly, suggesting that many air pollutants, even at very low levels, cause serious harm.

Particulate matter, especially PM2.5, can penetrate deep into the lungs and enter the bloodstream, causing effects on the cardiovascular, cerebrovascular (stroke) and respiratory systems. There is new evidence that particulate matter also affects other organs, leading to related diseases.

NO2 is associated with respiratory disorders, particularly asthma, leading to respiratory symptoms (such as coughing, wheezing, or dyspnea), hospitalization, and emergency room visits.

WHO revised air quality guidelines last year to make them more stringent to help countries better assess the health of their air.

"The current energy issue highlights the importance of accelerating the transition to cleaner, healthier energy systems," said Dr Tedros Adhanom Ghebreyesus, WHO Director-General. "High fossil fuel prices, energy security, and the urgency of addressing the two major health challenges of air pollution and climate change underscore the urgent need to accelerate the construction of a world less dependent on fossil fuels."

Measures that the government can take to improve air quality and health

Some governments are taking steps to improve air quality, but WHO is calling for swift and intensified action to:

Adopt or revise and implement national air quality standards in accordance with the latest WHO air quality guidelines

Monitor air quality and identify sources of air pollution

Support the transition to clean home energy for cooking, heating and lighting

Build safe and affordable public transport systems and networks that are convenient for pedestrians and bicycles

Implement stricter vehicle emissions and efficiency standards; implement mandatory inspections and repairs of vehicles

Invest in energy-efficient housing and power generation

Improve industrial and municipal waste management

Reduction of agricultural waste incineration, forest fires and certain agroforestry activities (e.g. charcoal production)

Integrate air pollution into the curricula of health professionals and provide tools for health sector involvement.

Particulate pollution levels are lower in high-income countries, but most cities have nitrogen dioxide problems

Of the 117 countries monitoring air quality, 17% of cities in high-income countries have lower air quality than WHO's air quality guidelines for PM2.5 or PM10. In low- and middle-income countries, less than 1% of urban air quality meets who recommended thresholds.

Globally, low- and middle-income countries are still more exposed to unhealthy PM levels than the global average. But no2 patterns are different, with smaller differences between high- and lower-middle-income countries.

About 4,000 cities/human settlements in 74 countries are collecting surface NO2 data. Overall, the measurements show that only 23 percent of people in these places inhale annual average concentrations of nitrogen dioxide that meet the latest version of WHO air quality guidelines.

"It is unacceptable that after the pandemic, there are still 7 million preventable deaths, and countless years of preventable loss of health due to air pollution. When we see a lot of air pollution data, evidence, and available solutions, that's what we're talking about. However, there are still too many investments being invested in polluted environments rather than in clean, healthy air," said Dr Maria Neira, Director of WHO's Department of Environment, Climate Change and Health.

Monitoring needs to be improved

People living in low- and middle-income countries are the most vulnerable to air pollution. They are also the least covered in terms of air quality monitoring – but the situation is improving.

Europe and, to some extent, North America, remain the region with the most comprehensive air quality data. In many low- and middle-income countries, while PM2.5 measurements are still not available, measurements have improved considerably since the last database update in 2018, where the number of human settlements monitoring air quality has increased by 1,500.

WHO air quality guidelines

The evidence base for the harm caused by air pollution has been accumulating rapidly. Evidence suggests that many air pollutants, even at low levels, cause significant harm. Last year, the World Health Organization responded by revising air quality guidelines to reflect this evidence and make them more stringent, especially for PM and NO2, a move that was strongly supported by the health community, medical associations and patient organizations.

The 2022 database aims to monitor the state of the world's air and inform progress tracking of the Sustainable Development Goals.

See more about the new data