The Iranian capital’s residents inhaled less clean air in April compared with the same period of last year, data from Tehran Municipality show.
Charts published by Tehran Air Quality Control Company website, Airnow.tehran.ir, show that clear blue skies were visible for only seven days in the month, meaning that the air quality index was under 50.
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).
TAQCC data show that during the month, “moderate” status was the most prevailing air condition, as the index hovered between 51 and 100 in April’s remaining 23 days.
The good news was that sensitive groups in the capital were not warned to limit their outdoor activities due to air pollution, as the index did not enter the threshold of unhealthy for the sensitive group (101-150).
Children, the elderly, pregnant women and those with respiratory and cardiovascular conditions fall in the above group.
Analyses illustrate that the pollutant responsible for the toxic index recorded in the month was PM2.5—atmospheric particulate matters that have a diameter of less than 2.5 micrometers.
TAQCC data indicate that air quality condition was comparatively better in the same period of last year.
In April 2019, AQI had 13 “good” and 17 “moderate” days.
Contributing Factors
Following the government’s temporary cancellation of the restrictive traffic rules in Tehran, the so-called “Traffic Scheme” and “Air Pollution Control Scheme” are not being enforced in the capital city. This is in line with efforts to help people observe social distancing criteria to prevent the COVID-19 disease from spreading further.
The Traffic Scheme is usually enforced in a 3,000-hectare area in the center of the city, where cars, except public transportation vehicles, are barred from entering the area between 7 a.m. and 6 p.m. Entering the zone costs up to 517,000 rials ($3.2) for private vehicles.
APCS defines an 88.5-square-kilometer area in central Tehran, which could be entered for free over a maximum of 20 days each season, or 80 days a year.
In addition to the fact that the suspension of the schemes has motivated citizens to use their private cars without being worried about getting charged or fined, the government also advised citizens to avoid the hazardous public transportation system as far as possible to flatten the curve of the novel coronavirus infection.
The measures have lead to more clogged roads and heavier traffic jam in the city and consequently more polluted air.
However, although the AQI charts show fewer days with “good” air quality, its difference with the index status in April 2019 is not significant. Therefore, slightly more polluted air this year cannot be solely blamed on private car emissions.
Supportive Study
Tehran Air Quality Control Company has conducted a study on the nature and sources of pollutants, which changes the long-presumed share of these factors in the chronic air pollution.
According to the study, these sources 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 quality.
PM2.5 is the most harmful due to its ability to penetrate deep into the lungs and blood streams, leading to heart attacks, respiratory diseases and premature death.
Mobile sources, including private cars, taxis, motorcycles, minibuses, buses, heavy-duty vehicles and airplanes, are blamed for the remaining 76%.
Based on these findings, the highest level of emission at 31% is spewed by passenger buses, 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%.
This is while not only have the capital’s urban managers always censured passenger vehicles for their detrimental effects on air pollution, but also set more stringent 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 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.
