Financial Tribune - The residents of Iranian capital breathed in more toxic particles in September, as air quality deteriorated slightly compared with the corresponding month of last year, data released by Tehran Air Quality Control Company show.

Charts published on TAQCC�s website, Airnow.tehran.ir, show that in September, Tehran�s residents were exposed to more polluted air.

This situation is expected to continue, as Iranian officials fail to take action against the production of highly polluting and substandard cars, one of the main sources of air pollution in Iranian metropolises.

Clear blue skies were not to be seen at all, as the air quality index did not improve during the period.

The index categorizes conditions dictated by a measure of polluting matters into good (0-50), moderate (51-100), unhealthy for sensitive groups (101-150), unhealthy (151-200), very unhealthy (201-300) and hazardous (301-500).