A member of Tehran city council has said that more than 20,000 Tehran residents die annually from air pollution.

A Sunday report by the semi-official ILNA news agency quotes Majid Farahani as saying that the figure has more than doubled since 2005.

Over the past few years, air pollution has on several occasions compelled Iranian authorities to close all schools and offices in the capital city.

Authorities have tried to reduce the city's air pollution by limiting the number of vehicles, blaming it on millions of old-fashioned motorbikes and cars stuck in prolonged traffic jams.