
The illustrations – which use colour coding to illustrate the severity of air pollution in cities across the world – contrast improvements across Europe with worsening air quality in parts of Africa and Central Asia.
The images illustrate the need for targeted international action on air pollution, which is thought to contribute to one in ten deaths worldwide, researchers say.
Known as Air Quality Stripes, the project was led by the Universities of Leeds and Edinburgh, alongside North Carolina State University and the UK Met Office.
Plotting pollution
Using computer simulations and satellite data, researchers charted trends in so-called particulate matter air pollution – such as dust, dirt and smoke – between 1850 to 2021.
Particulates are produced by human activities including industry, cars, agriculture, and fires caused by climate change, alongside natural sources such as volcanoes and deserts.
Exposure to particulate pollution has been linked with severe health conditions including respiratory diseases, cancers, and neurological disorders including Alzheimer’s and Parkinson’s.
Researchers used a colour-coded system of stripes to illustrate air quality, ranging from light blues – indicating levels within the World Health Organization’s 2021 Air Quality Guidelines – to oranges and blacks signalling the highest pollution levels.
The initiative was inspired by the climate stripes, created by Professor Ed Hawkins at the University of Reading, which has been widely used to illustrate global warming since 1850.
Global gap
The images show substantial improvement in air quality across European capitals including London, Edinburgh, and Berlin thanks to stricter regulations and technological advances.
Worsening air pollution in cities across central Asia and parts of Africa – such as Islamabad, Delhi and Nairobi – due to rapid urbanisation, industrial growth and limited regulation, is also revealed.
In some cities, natural factors such as desert dust and wildfires raised pollution levels while in others such as Jakarta, proximity to ocean breezes lowered particulate levels.
Illustrations were produced for every capital city with two additional cities for China, India, and the United States. The research team also included their own cities of Leeds and Exeter.