TEHRAN -- Tehran's Center for Pollution said here Monday that Carbon Monoxide (CO) in the air has been twice the limit in some parts of the city with heavy traffic, IRNA reported.

The center said higher levels of CO has put Tehran air condition in the unhealthy zone. Due to lack of wind and stillness of the air, "the CO has increased to about twice the limit in those parts of town with heavy traffic."

The forecasts are for more of the same weather pattern with partly cloudy skies and mild winds with the unhealthy air continuing.

Meanwhile, the level of other "air pollutants" remains at acceptable level, the center added.

Managing Director of Air Pollution Control Organization Saeed Abolhassani said here last month that Tehran experienced over 125 days of unhealthy air pollution during the last Iranian year (ended March 20).

He added that in some days the pollution level came close to dangerous levels. Per international standards the pollution level should not exceed standards in more than one day in a year, Abolhassani underlined.