The 2024 IQAir World Air Quality Report published this morning contains some positive news tempered, as one might expect, by sobering reminders that global air quality still has a lot of scope for improvement.
The report reveals that 17% of cities met the WHO annual PM2.5 guideline level, almost double the 9% which met the guideline last year.
The 2024 Report includes data from 40,000 air quality monitoring stations across 8,954 cities in 138 countries (up from 7,812 locations in 134 countries in 2023). Last year there was insufficient data from Chad for the country to be included but they are back this year, reclaiming their title as the most polluted country on Earth.
A major contributory factor in Chad’s figure is its exposure to severe dust storms originating out of the Bodélé Depression, which can affect the country for up to 100 days a year (pictured above).
Djibouti and Mozambique are also included this year, while a lack of data means Iran, Afghanistan, and Burkina Faso are absent.
The five most polluted countries in 2024 were:
1. Chad: 91.8 μg/m³ (more than 18 times higher than the WHO PM2.5 annual guideline)
2. Bangladesh: 78.0 μg/m³
3. Pakistan: 73.7 μg/m³
4. Democratic Republic of the Congo: 58.2 μg/m³
5. India: 50.6 μg/m³
The above are the only countries that managed to exceed the WHO guideline of 5 µg/m³ by more than 10 times.
12 countries recorded PM2.5 concentrations below 5 µg/m³, the best performing being Bahamas, Bermuda and French Polynesia. Also below the guidelines were Estonia, Australia, New Zealand and Iceland.
The IQAir report uses empirically measured PM2.5 data gathered from ground-level air monitoring stations. The data is sourced from both regulatory air quality monitors and low-cost sensors, operated by a wide range of organisations — including government agencies, academic institutions, non-profits, and individual citizens committed to monitoring local air quality. Most of the data featured in the World Air Quality Report is collected in real-time, supplemented by year-end historical datasets to provide the most comprehensive global analysis possible.
The most polluted metropolitan area on Earth was Byrnihat in India, with an annual average PM2.5 concentration of 128.2 μg/m³. Of the nine most polluted cities, six of them were in India.
At the other end of the scale, Mayaguez in Puerto Rico recorded an annual average PM2.5 concentration of just 1.1 μg/m³.
The lack of reliable data coming out of Africa has long been a problem and this yea IQAir point out that across the continent, there is only one monitoring station for every 3.7 million people.
Elsewhere, it is noted that wildfires in the Amazon rainforest affected the air quality across large parts of South America last year, with PM2.5 levels in some Brazilian cities quadrupling in September.
In light of IQAir’s Schools4Earth initiative, which aims to bring real-time air quality monitoring to schools across the world, the report also explains how particulate matter poses a particular health risk to children.
Frank Hammes, Global CEO of IQAir said: ‘Air pollution remains a critical threat to both human health and environmental stability, yet vast populations remain unaware of their exposure levels,” said “Air quality data saves lives. It creates much needed awareness, informs policy decisions, guiding public health interventions, and empowers communities to take action to reduce air pollution and protect future generations.’
Aidan Farrow, Senior Air Quality Scientist with Greenpeace International said: ‘The World Air Quality Report, which compiles measurements of air pollution from around the globe, should be a rallying call for urgent and concerted international efforts to cut pollutant emissions.
‘By highlighting the disproportionate risk posed to young people by air pollution, the report reminds us that a failure to act today will be felt by future generations, while frequent references to human activities like coal burning and deforestation are a reminder that air quality, climate change, and the world that will be inherited by our children are inextricably linked.’
The full report can be read here.
