Hossein Shahidzadeh added that over 3.43 million passenger cars ply the capital’s streets every day, 100,000 of which are over 18 years old and have outlived their usefulness, Mehr News Agency reported.
He added that these old cars emit 579,000 tons of toxins into the air annually, which means 1,586 tons a day.
Giving more specific information, Shahidzadeh noted that of all the pollutants spewed into Tehran’s air annually, these dilapidated cars are responsible for 82% of sulfur oxide, 23% of PM2.5 and PM 10 (atmospheric particulate matters that have a diameter of less than 2.5 and 10 micrometers respectively), 46% of carbon monoxide and 45% of nitrogen monoxide.
He also said PM2.5 is the most harmful pollutant due to its ability to penetrate deep into the lungs and bloodstreams unfiltered, causing heart attacks, respiratory disease and premature death.
Shahidzadeh called the officials in charge to more seriously monitor the technical efficiency of cars plying Tehran’s streets. He also warned the urban managers on the danger of canceling the traffic rules for any reason.
However, comparisons have shown that the implementation of traffic schemes have not had much effect on curbing air pollution in the city.
With the outbreak of Covid-19 in the country, municipal bodies in Tehran lifted the traffic limits in late March and early August, to discourage the public from using public transportation to curb the spread of the virus. But the measure led to clogged roads and heavy traffic in the city.
According to Mohammad Rastegari, the head of the Department of Environment, told reporters that in both rounds, the resumption of traffic schemes in the capital has had close to zero effect on air pollution.
“Air quality data recorded daily by TAQCC show no decline in air pollution levels after the resumption of traffic restrictions in the city,” 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 levels and it can only cause minor changes.
Share of Pollutants
Rastegari’s words are supported by a study conducted by TAQCC on the share of different sources in Tehran’s air pollution.
The study divides the sources 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 by 31%, even more than all the stationary sources of pollution in the city.
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%.
AQI Moves Higher Again
Charts published by TAQCC’s website, Airnow.tehran.ir, show that since Sunday, Tehran’s residents have been exposed to polluted air consecutively.
According to the company’s information, in the past four days, Air Quality Index has passed the threshold of moderate condition entering the range of unhealthy for the sensitive group.
The index categorizes conditions dictated by a measure of polluting matters into good (0-50), moderate (51-100), unhealthy for sensitive groups (101-150), unhealthy (151-200), very unhealthy (201-300) and hazardous (301-500).
Children, the elderly, pregnant women and those with respiratory and cardiovascular conditions were warned to limit their outdoor activities in the four days.
TAQCC data show that since the beginning of fall (Sept. 22), the remaining 19 days, moderate status was the prevailing air condition, as the index hovered between 51 and 100.
The analyses indicate that the pollutant responsible for the toxic index recorded in the concerned period was PM2.5.
Tehran is notorious for the high density of PM2.5 in the cold seasons and temperature inversion is the most frequent term cited in air quality reports.
The phenomenon occurs with the drop in temperature, with the cold air underpinning warm air at higher altitudes, leading to the entrapment of air pollutants causing heavy smog.
Air pollution kills thousands of innocents per year and the so-called remedies devised by municipalities, including a variety of traffic rules with different criteria, seem to be ineffective.
In view of Covid-19 still spreading in the country, the supposedly increasing air pollution in the coming days is expected to make the situation worse.