Local authorities announced on Sunday they would impose traffic restrictions in Tehran allowing cars onto the streets in alternating shifts. Average concentrations of the finest and most hazardous airborne particles hit 144 microgrammes per cubic metre in Tehran on Sunday and peaked at 169 in some areas, municipal authorities said.
That is far above the World Health Organization’s recommended maximum of 25 microgrammes per cubic metre on average over a 24-hour period. Iranian media reports say 80 percent of the pollution in Tehran is caused by fumes from vehicle exhaust pipes.
