Air pollution is easy to overlook. It is often invisible, it drifts across borders and, on a normal day, it may not feel like much of a threat. The numbers tell a different story, however, and the air around us says a lot about how we live, so here are five things worth knowing about the air we breathe:
Almost everyone is breathing air that is too polluted
In 2023, 99 per cent of the world’s population lived in places where air pollution exceeded the World Health Organization’s strictest guideline for fine particles, the UN Environment Programme's (UNEP) Pollution Action Note shows. These particles are tiny enough to travel deep into the lungs and can also affect the heart and brain and are called “fine particulate matter”, also known as PM2.5. And PM2.5 is only one part of the picture. Ground-level ozone, nitrogen dioxide, carbon monoxide and other pollutants can also harm human health and ecosystems.
Air pollution can travel a very long way
Polluted air does not stop at the border. Fine particles can be carried hundreds or even thousands of kilometres, depending on wind and atmospheric conditions. Ground-level ozone can travel across countries too. That makes air pollution a problem that no city or country can solve entirely on its own. Even a blue sky does not mean the air is clean. Fine particles or other pollutants do not need to be visible to cause harm, which makes air pollution so easy to miss.
The sources of air pollution vary from place to place
Some sources are surprisingly ordinary. Globally, residential sources account for about 19 per cent of particle concentrations, while windblown dust accounts for around 16 per cent, UNEP – who annually organizes the international day of clean air for blue skies on 7 September with its convened Climate and Clean Air Coalition – explains. Transport, industry, energy production, agriculture and fires add to the mix. In many lower-income countries, burning wood, charcoal or coal for cooking and heating is a big source of pollution inside homes, for example.
Air pollution is a major cause of premature death
An estimated 7.9 million deaths worldwide are attributed to air pollution in 2023. Outdoor fine particles account for 4.9 million of those. The diseases linked to air pollution include chronic obstructive pulmonary disease, heart disease, stroke, lung cancer and lower respiratory infections. Long-term exposure to ground-level ozone is estimated to contribute to 500,000 premature deaths each year. Exposure to air pollution was estimated to reduce average global life expectancy by about one year and eight months in 2021.
Cleaner air and climate action often go together
Ground-level ozone can reduce the productivity of crops and harm vegetation, while particulate pollution can affect ecosystems and the climate. Many air pollutants and greenhouse gases come from the same sources, in particular from the burning of fossil fuels. Cutting that burning can therefore bring several benefits at once, such as cleaner air, healthier ecosystems and less warming.
