Financial Tribune- Tehran experienced the highest air quality in the Iranian month of Khordad (May 22�June 21) in the past six years, data on Tehran Municipality�s air quality website showed.

Based on World Health Organization Guidelines, air quality indices are split into six categories: clean (0-50), healthy (51-100), unhealthy for sensitive groups (101-150) unhealthy (151-200), very unhealthy (201-250) and dangerous (251+).

According to data retrieved from airnow.tehran.ir, Khordad had 28 healthy days with the AQI exceeding the 100 threshold on only three days.

The data for the previous six years can be found in the table below:

Since taking office in 2013, President Hassan Rouhani�s administration has taken steps to reduce air pollution in Iran�s metropolises, including the distribution of Euro-4 quality petrol, obliging automakers to produce Euro-4-compliant vehicles, banning the production of carburetor-equipped motorcycles and pushing TM to renovate its aging taxi fleet.

Air pollution inflicts upward of $30 billion in losses on Iranians, Massoumeh Ebtekar, a vice president and head of the Department of Environment, said.

More than 4,400 people die every year of diseases attributed to poor air quality in Tehran, according to statistics by the Health Ministry and World Health Organization.