Air pollution in the Greater Tehran Area (GTA), Tehran, Iran

Urban air pollution

The air pollution is due to several different reasons:

Economical: most Iranian industries are located on the outskirts of Tehran. The city is also overrun with old and aging cars which do not meet today's emission regulations. Furthermore, Iran's busiest airport, Mehrabad International Airport, is located in the west of the city.

Infrastructure: Tehran has a poor public transportation network. Buses and metros do not cover every area of the city. Most people are then obliged to either use private cars or hire taxis. According to the statistics recently released by the Automobile Technical Tests Center, over 1,200,000 vehicles in Tehran are more than 20 years old and lack catalytic converters that filter auto exhaust. The situation is worsened by the widespread use of low-quality, leaded gasoline.

Geographical: Tehran is bound in the north by the massive Alborz mountain range that is stopping the flow of the humid Caspian wind. As a result, thermal inversion that traps Tehran's polluted air is frequently observed. The lack of humidity and clouds makes Tehran a very sunny city. The UV radiations then combined with the existing pollutants significantly raise the level of the ozone.

The government, however, is engaged in a battle to reduce the air pollution. Research conducted in 1997 by the Tehran Municipality involved the cooperation of two international organizations: the World Bank (providing $2 million in aid) and Japan�s International Cooperation Agency (supported by UNICO and the Japan Meteorological Association).
Since September 2002 the three years Study on Strengthening and Improving Air Quality Management in the Greater Tehran Area has been initiated.

Considering that 73% of air pollution in Tehran is produced by vehicle emissions, several projects have been, and are being, undertaken. For example, unleaded gasoline was introduced in the Iranian year 1380 (starting 21 March 2001), and diesel fuel with a minimal amount of sulfur also became available. From 21 March 2002, all gas stations would sell unleaded fuel with octane levels of 87 and 95.

Regarding heavy vehicles that traditionally use diesel fuel, the government has announced that all buses and minibuses manufactured since 21 March 2000 should have the capability to use gas, according to EURO1 standard. Gas fuelled buses and mini-buses (LPG and CNG) should also meet the ECE 13.04 standard.
Furthermore, since 1979 the government has setup a "Traffic Zone" covering the city center during peak traffic hours. Entering and driving inside this zone is only allowed with a special permit.
The government is also trying to raise people's awareness about the hazards of the pollution. One method that is currently been employed is the installation of Pollution Indicator Boards all around the city to monitor the current level of particulate matter (PM10), nitrogen dioxide (NO2), ozone (O3), sulfur dioxide (SO2), and carbon monoxide (CO). The board also displays the Pollutant Standards Index (PSI), which is a general indication of air quality based on the measurements of the above-mentioned five pollutants. The Pollution Indicator Boards classify the level of each pollutants as either safe, hazardous or dangerous.
In 2007 Iran imposed fuel rations in order to reduce fuel consumption. Since the use of cars has thereafter declined, streets are less congested and the air quality has improved.

The following table illustrates the names and dates of agreements signed by Iran relating to air pollution:

• Regional Protocol to Control Pollution from Oil and Related Materials in Emergencies � Kuwait, 1978
• Vienna Convention to Protect the Ozone Layer, 1985
  
• Montreal Protocol on the Materials Diminishing the Ozone Layer, 1987
• UN Convention on Climatic Change � New York, 1992