Financial Tribune - The increasing number of dilapidated vehicles plying the streets, ineffective remedial schemes, inefficient urban management and climate change effects have made living and breathing in an expanding and highly polluted metropolis like Tehran very difficult.

Based on the data released by Tehran Air Quality Control Company, Tehran�s residents have breathed a varying dose of toxic emissions in all the months of January over the past five years.

A close analysis of Air Quality Index during the period makes this very clear. AQI is used by government agencies to announce the prevailing level of air pollution, or how polluted it is forecast to become.

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).