The report suggests that despite general global air quality improving, some countries are failing to meet targets and others still have extremely high pollution levels. Unfortunately, the impacts of this can be felt most strongly in developing countries which depend upon fossil fuels, thus producing higher levels of pollutants.
The full article provides further information including the most polluted country and urban area - https://www.theguardian.com/environment/2024/mar/19/air-pollution-health-report