Mohammad Rastegari, the head of DOE's Environmental Monitoring Office, told Borna News Agency that air quality data recorded daily by Tehran Air Quality Control Company show no decline in air pollution levels after the resumption of traffic restrictions in the city.
After the coronavirus outbreak in Iran, traffic schemes in Tehran were halted in late February on the government's order to discourage people from using the hazardous public transportation and cut the infection chain.
“Now that the rules are back, air quality has failed to improve,” Rastegari said.
He added that over half of Tehran's air pollution is caused by toxic particles released from vehicles and the rest is generated by a variety of fluctuating factors.
"Tehran's air quality is a fundamental issue that cannot be solved with short-term solutions or overnight. It is a multivariable equation that cannot be simply changed," he said.
Pointing to the decisive effect of environmental phenomena, such as wind, on air quality, the DOE official said wind can be much more effective than the most strict traffic schemes, for it can disperse pollution and change air stability in a few hours.
This is why, he added, traffic schemes alone cannot reduce air pollution level and it can only make minor changes.
The "Air Pollution Control" and "Traffic Scheme" are two restrictive rules halted in Tehran.
As per the APC scheme, each vehicle can enter a "restricted zone" in central Tehran for free for a maximum of 20 days each season, or 80 days a year.
Spread over 88.5 square kilometers in central Tehran, the zone is bounded by Imam Ali Expressway in the east, Navvab Expressway and Chamran Highway to the west, Besat Expressway in the south and Hemmat Expressway in the north.
The more stringent “Traffic Scheme” in central Tehran is enforced in an area limited by Motahari Street in the north, Shariati Street in the east, Kargar (west) and Shoosh (south) where cars, except public transportation vehicles, are barred from entering the area between 8 a.m. and 5 p.m.
Entering the zone costs up to 520,000 rials ($2.7) for private vehicles.
AQI in Detail
Referring to TAQCC charts, Rastegari said since traffic schemes resumed in Tehran, AQI has risen above 100 in four days, which means air quality was unhealthy for kids, the elderly, pregnant women, cardiovascular and respiratory patients who are categorized as "sensitive groups".
The index categorizes conditions dictated by a measure of polluting matters into good (050), moderate (51-100), unhealthy for sensitive groups (101-150), unhealthy (151-200), very unhealthy (201-300) and hazardous (301-500).
In the remaining nine days, the index had a moderate status, Rastegari added.
The data show air in Tehran was more breathable before the restrictions were employed. In the month that ended on June 6, AQI was unhealthy for sensitive groups only on two days. The index held its moderate status in the remaining days.
Share of Pollutants
Rastegari's argument is reminiscent of a game-changer study on air pollution factors earlier conducted by TAQCC.
The company investigated the nature and sources of air pollutants, which changes the long-presumed share of these culprits in chronic air pollution.
The study names pollutants affecting air quality as carbon monoxide, carbon dioxide, nitrogen monoxide, nitrogen dioxide, sulfur dioxide, ground-level ozone and particulate matters (PM2.5 and PM10).
However, the study shows that among all pollutants, particulate matters, especially PM2.5, are the most harmful due to their ability to penetrate deep into the lungs and bloodstreams unfiltered, causing heart attacks, respiratory disease and premature death.
The sources of pollutants are mainly divided into stationary and mobile modes. Stationary sources, which include industrial units, generate 24% of the total PM2.5 in Tehran’s air.
Mobile sources are responsible for the remaining 76%, including private cars, taxis, motorcycles, minibuses, buses, heavy-duty vehicles and airplanes.
Until now, almost all analyses are compatible with the previous data. But the interesting part is the share of each source in the category.
According to new data, the highest level of emission is spewed by passenger buses at 31%, even more than all the stationary sources of pollution.
Heavy-duty vehicles are the next most polluting source with 23.7%, followed by motorcycles with 10%, airplanes with 5% and minibuses with 4.3%.
The data illustrate that the least polluting groups are private vehicles and taxis with a respective contribution of 1.6% and 0.4%.
This is while not only have the capital’s urban managers always censured passenger vehicles for their detrimental effects on air pollution, but have also set several traffic regulations, schemes and fines to curb the use of private cars.
Weak efforts to relocate 300 industrial units in Tehran have been to no avail.
Over the past many years, city councilors and the mayor have failed to address the issue effectively, blaming others for the worsening air pollution.
Smog in Tehran takes the lives of over 3,500 people every year, Iran’s Health Ministry reported.