Sources of Air Pollution
Air pollution originates from a variety of sources. In cities, most of these are human-made, meaning they can be solved through targeted action. These sources can be grouped into four main types:
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Air pollution is one of the biggest threats to our health, our climate, and our cities. Today, 41% of cities in the world have air pollution that is over 7 times higher than the World Health Organization’s recommendation. Without urgent action, the costs will continue to rise — in lives lost, health systems strain, and economic damage.
But it does not have to be this way. There are solutions. With investment and collaboration, cities can be at the forefront of delivering those solutions so that everyone who works, lives in, or visits them can breathe cleaner air.
Air pollution refers to harmful gases and particles in the air that change its natural composition. The World Health Organization (WHO) identifies common sources as household burning of fuels such as coal and wood for cooking and heating, motor vehicles, industrial facilities, and forest fires. Worldwide, most major sources of air pollution are man-made and involve the burning of fossil fuels or biomass.
Two common air pollutants are PM2.5 and nitrogen oxides (NOx). PM2.5 refers to tiny particles floating in the air — like bits of dust, smoke, ash, or soot. Nitrogen oxides are gases that form when fossil fuels like coal, petrol, or diesel are burned and mix with oxygen in the air.
Pollution doesn’t stay put. Wind and atmospheric reactions can transport pollutants far from where they originated, transforming them along the way. For example, areas downwind from power plants or cities can experience smog or haze.
Air pollution originates from a variety of sources. In cities, most of these are human-made, meaning they can be solved through targeted action. These sources can be grouped into four main types:
For example, vehicles such as cars, buses, planes, boats and trains.
These include agricultural areas and wood-burning fireplaces.
Power plants, factories, construction sites, waste landfills and oil refineries emit large amounts of pollution from fixed locations.
Events like wildfires, wind-blown dust, and volcanic eruptions can contribute to pollution. These are typically short-term, but the intensity of wildfires is increasing due to climate change.
The consequences of air pollution are significant, impacting everything from human health to our economy and the climate.
It contributes to serious illnesses like asthma and heart disease, fuels climate change, affects people differently depending on where they live or work, and costs the global economy trillions each year.
With 68% of the world’s population expected to live in urban areas by 2050, cities are at the frontlines of the air pollution crisis. But they also hold the tools to tackle it. From transport and energy to waste and buildings, there are so many ways to clean the air in our cities. When cities act, the results are real and rapid: cleaner air, better health, resilience to the climate crisis, stronger communities, fairer outcomes for the people who need it most and a healthier world for future generations. That’s why Breathe Cities partners with local leaders, communities and experts to drive bold action where it counts the most.
Reducing air pollution is a win-win strategy for our climate, health, people and our economy. Solutions vary, but can include:
The Breathe Cities initiative works across 14 cities globally to address air pollution. By supporting local governments, working with communities, expanding air quality data, and sharing lessons learned, the initiative aims to reduce pollutants, improve public health, and inspire more cities to take action.
Together, we can create healthier, thriving communities.