The global concentrations of particulate matter have been graphically illustrated for the first time by a team of scientists.

Data from computer simulations and satellite observations were combined to estimate the changing concentrations of particulate matter since the beginning of the industrial revolution, with the colur palette for the stripes devised by an artist who analyzed more than 200 online images of “air pollution” to identify the dominant color palettes.

The Air Quality Stripes, which were created by the University of Leeds, the University of Edinburgh, North Carolina State University, and the UK Met Office, starkly contrast the significant improvements in air quality across much of Europe with the deterioration in parts of Africa and Central Asia.

The project’s findings highlight both the successes and ongoing challenges in tackling air pollution worldwide.

There are stripes for the capital city of every nation worldwide with two additional cities for China, India, and the United States. The research team also included their own cities of Leeds, Edinburgh, and Exeter.

AQ stripes for Islamabad, illustrating the timeline from 1850 to 2021, with black for ver poor and blue for fair. the latest data shows that air quality is still very poor.

The lightest blue stripes meet the World Health Organization Air Quality Guidelines which were introduced in 2021, with all other colors exceeding the guideline values.

Key findings:

• Europe’s Air Quality Gains: The images show substantial reductions in particulate matter levels across most of Europe (predominantly Western Europe). Stricter air quality regulations and technological advancements have successfully reduced particulate matter concentrations in most European cities (e.g. London, Brussels, Berlin).

• Worsening Conditions in Central Asia and parts of Africa: The visualisations reveal a concerning rise in particulate matter pollution in many cities in central Asia and Africa (e.g. Islamabad, Delhi, Nairobi). Rapid urbanization, industrial growth, and limited regulatory frameworks are contributing to this troubling trend, which poses significant health risks to local populations.

• Global Disparities: The images highlight the stark disparities in air quality progress between different regions.

The influence of natural sources was particularly notable in some locations, these sources include desert dust and wildfires, proximity to the coast was often quite noticeable with locations such as Jakarta having lower levels than might be expected.

The World Health Organization recommends that the annual average concentration of PM_2.5 should not exceed a concentration of 5 micrograms per cubic meter air (5 ug/m³). This new guideline is a concentration which is generally classed as very good air quality. There is no safe level of PM_2.5 recognized by medical science.

At present, 99% of the world’s population live with concentrations above this value, with the highest PM_2.5 levels typically found in low- and middle-income countries.

The AQ stripes use an annual average to take account of the ups and downs due to changes in weather patterns throughout the year, and to make comparison between locations simpler. However the researchers point out that even short-term exposure to very high levels can quickly have acute health effects requiring medical treatment.