Tehran Struck by Smog

The sprawling Iranian capital Tehran has been shrouded in the all-too familiar smog for the past three days, with one major difference compared to past years: It has happened earlier.

Every year with the drop in temperature in winter, a phenomenon known as temperature inversion occurs during which cold air underpins warm air at higher altitude, leading to the entrapment of air pollutants in the city, which causes heavy smog.

Denizens of Tehran and other metropolises have gotten used to seeing this level of smog in late December or early January, but this year the phenomenon has struck more than a month earlier than expected.

What makes the issue even more alarming is that there has not been a significant or sudden drop in temperature compared to a month ago, which is expected to dip as the specter of winter looms.

In an interview with Financial Tribune in September, Massoumeh Ebtekar, the head of the Department of Environment, said the level of air pollution this winter would not be as bad as previous years.

However, five major cities, namely Tehran, Arak, Isfahan, Karaj and Qazvin, have all been experiencing severely polluted air in the past few days and winter is more than a month away.

  Out of Control

An official at the Public Relations Office of Tehran Air Quality Control Company attributes the current situation to a number of natural and uncontrollable meteorological parameters such as wind speed, atmospheric stability and lack of air turbulence.

Wind speed is essential in how quickly pollutants are carried away. However, strong winds do not always disperse the pollutants but can transport pollutants en masse to a larger area. The speed of wind in Tehran (averaging 7 km/h) has done little to alleviate air conditions in recent days.    

"Tehran's atmosphere has experienced stable conditions for days (i.e. no sudden drop in air pressure that could cause winds), which has only contributed to pollutants becoming trapped near ground level," the official, who did not want to be named, told Financial Tribune on the phone.

The early arrival of the smog has cast doubts on the quality of the distributed gasoline, which is claimed to comply by Euro-5 standards in Tehran and Euro-4 in other metropolises.

The company, however, maintains that the current air quality is due to natural factors that are beyond human control.

Tehran experienced its most polluted day of the current Iranian year (started March 20) on Monday, when sensors registered an air quality index of 156 with a "red status", which means the level of toxic pollutants in the air posed health risks to each and every person and not just those deemed vulnerable, according to World Health Organization standards.

The phenomenon of inversion, which is often expected at lower temperatures, is also said to occur temporarily and for a few hours.

However, its persistence and the advancing winter have triggered public concerns that air pollution will worsen.

Will the DOE do something to alleviate these concerns, apart from issuing statutory warnings and recommending the closure of schools?