Air pollution levels are increasing worldwide. According to data from the international air quality technology company IQAir at around 9:30 am on Tuesday, the world's most polluted city is Sarajevo, Bosnia and Herzegovina, with an air quality score of 446. This is risky for citizens. Dhaka is in second place, with a score of 308, which also identifies the city's air as 'very unhealthy'. Hanoi, Vietnam, is in third place, with a score of 232.

Air quality is assessed through the AQI (Air Quality Index) score. A score of 0-50 is considered good, 51-100 is moderate, 101-150 is unhealthy (especially for sensitive groups), 151-200 is unhealthy, 201-300 is very unhealthy, and a score of 301-400 is considered risky, which can pose a serious health risk to citizens. Air pollution levels are measured by particulate matter (PM10 and PM2.5), NO2, CO, SO2, and ozone (O3).

Experts advise children, the elderly, and the sick to stay indoors, and others to limit outdoor activities, especially in situations where the AQI score is very high.