Why the air you breathe that was considered safe is no longer safe, according to the WHO

Air pollution is more dangerous than previously thought.

That’s the conclusion reached by the World Health Organization (WHO), which has updated air pollution thresholds for the first time in 16 years.

The reason? More than 90% of the world’s population breathes pollution levels much higher than those considered safe.

This leaves far behind the latest WHO indicators, which were in force since 2005.

Why is this happening? Scientists are finding more and more evidence of adverse effects of six types of pollutants on human health: PM2.5 and PM10 suspended particles; ozone (O3); carbon monoxide (CO); sulfur dioxide (SO2) and nitrogen dioxide (NO2).

With this measure, the WHO makes it clear that even air considered safe until now is no longer so because pollutants are dangerous to health even at low levels and tolerated until now.

It is estimated that more than 7 million people die prematurely each year as a consequence of air pollution.

This equates air pollution with smoking and unhealthy eating.

“The accumulated evidence is sufficient to justify actions to reduce the population’s exposure to key air pollutants, not only in particular countries or regions, but on a global scale,” the organization said in a statement.

Because right now?

Scientists have a hard time understanding how pollutants affect human health.

Not only because exposure to high levels is already harmful. But because we are also exposed to a combination of several of them.

Some, such as suspended particles smaller than 10 microns (PM10) and 2.5 microns (PM2.5) have a very varied origin.

It is known that they may come from the burning of fuels, including transportation, energy, households, industry and agriculture.

They are also particles so small that they can penetrate the lungs and enter the bloodstream.

Several epidemiological studies have indicated that exposure to PM2.5 can affect health even at low levels.

They are mainly associated with heart and lung diseases. Even short-term exposure, for hours or days, can increase the risk of hospital admission.

The WHO had to review more than 500 studies (including several rounds of peer reviews) to determine that much stricter levels of air pollution are needed to protect human health.

Nearly 80% of PM2.5-related deaths worldwide could be prevented if current levels of air pollution were reduced to those proposed in the updated guideline, according to a rapid scenario analysis conducted by WHO.

Disparities in exposure to air pollution are increasing around the world, particularly as low- and middle-income countries are experiencing increasing levels of air pollution due to large-scale urbanization and economic development which has relied heavily on the burning of fossil fuels.

New measures

In the case of PM10, the WHO lowered the annual exposure limit from 20 micrograms per cubic meter to 15.

For PM2.5, the reduction is half: from 10 micrograms per cubic meter to 5.

New limits have also been introduced for nitrogen dioxide NO2, a pollutant that causes problems in the respiratory system and is closely linked in cities to diesel and gasoline vehicles.

The new guidelines emphasize other pollutants, such as carbon monoxide, ozone and sulfur dioxide, as a preventive measure pending further scientific evidence.

However, the new WHO guidelines are not binding. In other words, it will be up to governments to take the necessary measures to improve air quality.

Although the WHO assures that a reduction in air pollution levels would bring sustainable benefits, it also clarifies that there are no completely safe levels.

The WHO said that while air quality had improved markedly since the 1990s in high-income countries, the global number of deaths and years of healthy life lost had barely decreased as air quality in general had declined. deteriorated in most other countries.

“Air pollution is a threat to health in all countries, but it affects people in low- and middle-income countries the most,” said WHO chief Tedros Adhanom Ghebreyesus.

The new guidelines come just weeks before the United Nations Climate Change Conference (COP26) begins in the Scottish city of Glasgow on October 31.

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