Iran’s capital Tehran on Friday had the worst air quality index in the world, according to data by IQAir -- a global air quality monitoring company.

The company’s real-time air quality index (AQI) for Tehran was 206 on Friday, putting the Iranian capital on top of the list followed by Beijing and Pakistan’s Lahore with AQIs of 182 and 173, respectively.

According to the Swiss company that specializes in protection against airborne pollutants, the index of over 200 is considered ‘Very Unhealthy’.

The air quality is not much better in other Iranian cities like Esfahan, and people have been warned against going out, as a wave of dust carrying pollutants has hit the country from neighboring Iraq.

An official from Iran’s meteorological organization, Mohammad Asghari, told state broadcaster IRIB on Friday that 26 provinces of the country will be engulfed by dust in the coming days.

Using another pollution standard, Asghari said Tehran’s air quality index was 491, which is only nine points less than the maximum level in this scale and is considered ‘Hazardous’.

Pollution in Tehran also forced authorities to cancel outdoor sport matches scheduled for Friday while schools have gone virtual again only a week after they opened following the New Year holidays and a year of Covid-19 restrictions.

Air pollution is a persistent problem in large Iranian cities, especially in cold and hot weather when more electricity is used and power stations resort to using heavy dirty diesel fuels because of natural gas shortages.