Proposed by Tehran Transportation Council after talks were held among environmentalists and urban planners, the Air Pollution Control scheme was launched on June 22.
Hossein Shahidzadeh, deputy director of Tehran Air Quality Control Company, says long-term data collection and monitoring are needed to get a comprehensive overview of the scheme and its impacts, ISNA reported.
“Data collected over the past two and a half months after the launch would not be sufficient to conduct a comprehensive study and produce a credible assessment about the scheme,” Financial Tribune quoted him as saying.
However, the official underlined that TAQCC data show that since APC was launched in the capital, the density of carbon monoxide (CO) has significantly decreased in the air.
Technically, air pollutants are categorized into two groups of gas pollutants and particulate matters. The former includes carbon monoxide, nitrogen dioxide, sulfur dioxide and ground-level ozone. Atmospheric particulate matters that have a diameter of less than 2.5 and 10 micrometers—known as PM2.5 and PM10 respectively—are classified in the second group.
"The main source of carbon monoxide is toxic emissions released by polluting vehicles plying the street. The shrinking density of CO in the air during summer compared with the same period of last year shows APC has been at least partially effective," Shahidzadeh said.
Pointing to the poor air quality of Tehran in the early days of autumn, which coincide with the beginning of the new academic year, Shahidzadeh said, "This has less to do with vehicles' toxic emissions, for the dim sky in late September was due to a sudden dust storm filling up the atmosphere with a huge volume of PM10 particles."
Therefore, he said, the low air quality in the early autumn days should not be interpreted as the deficiency of any traffic or air pollution scheme.
Modification Required
Brigadier General Mohammad Reza Mehmandar, the head of Tehran Traffic Police, told the media that at first, every scheme is a drafted idea, the implementation of which will most probably reveal its deficiencies.
"Urban managers must scrutinize APC's positive and negative results, and modify the scheme accordingly," Mehmandar added.
Narrowing down the case to time limitations defined by the scheme, he suggested that small and sensible changes in APC time restrictions will most probably ease traffic congestion during the rush hours.
The arguments were all reactions to the complaints earlier raised by Hojjat Nazari, a member of Tehran City Council, who had censured the APC scheme, calling for its cancellation.
Last week, Nazari told Mehr News Agency that APC has had a harmful effect on air quality.
"People in the capital judge the schemes based on observable results. The grey sky in Tehran and clogged roads are what the general public are struggling with these days," he added.
How It Works
As per APC, 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.
Vehicles are barred from entering the area between 6:30 a.m. and 7 p.m. on all days, except Fridays and national holidays. On Thursdays, the time limit is between 6:30 a.m. and 1 p.m.
If motorists wish to enter the zone more than the number of times allowed in the plan, they need to pay a toll fee.
Odd-Even Scheme
APC was proposed as an alternative for the odd-even scheme, which was implemented in Tehran in 2005.
As per the odd-even rule, cars entered the designated restricted zone on alternate days, depending on the odd and even number of the license plate.
Saturday was earmarked for cars with the last even digit and Friday, being the weekend, was free for all cars.
According to experts, the old scheme failed to deliver.
Soon after its introduction, the odd-even scheme helped curb air pollution. However, as time passed, the scheme simply lost its usefulness and even gave rise to undesirable results. Pollution and smog were intensified.
Tehran Urban Research and Planning Center, in collaboration with centers of higher education, carried out extensive studies on the effectiveness (or lack of it) of the odd-even scheme to determine how to curb the omnipresent air pollution and traffic congestion in the city of 9 million people.
Study results showed that mismanagement and the improper implementation of the odd-even scheme had an adverse effect on air quality. The scheme was initially planned to be a temporary measure to curb air pollution only during a crisis period.
The survey also indicated that car owners whose license plates ended with an odd number drove in the restricted zone for 39 days each season, while motorists whose number plates ended with an even number plied in the zone for a much lower number of times (26 days).
Other Measures
In addition to APC, two other initiatives are underway in the capital to help curb the smog and ease the pervasive traffic congestions.
Tehran Municipality launched the Air Pollution Reduction scheme in November 2018 to help improve air quality. Based on the plan, old and dilapidated vehicles are banned in the city and violators were fined.
APR compels many car owners to have their vehicles checked or face consequences. All two- and four-wheelers are required to undergo mandatory inspections and receive technical papers that confirm the vehicles are roadworthy.
Another so-called “Traffic Scheme” in central Tehran was enforced in an area limited by Motahari Street in the north, Shariati Street in east, Kargar (west) and Shoosh (south) where cars, except public transportation vehicles, are barred from entering the area between 6 a.m. and 7 p.m. Entering the zone costs up to 414,000 rials ($3) for privately- owned vehicles.
Like many expanding metropolises across the world, Tehran has long been struggling with air pollution and traffic jam. Although public and urban managers might become tired of the constant trial and error of launching and scrapping different plans to tackle the issues, field studies, strong management and patience seem to be the only effective strategy to resolve the urban problems.