Tehran has been suffocating under a blanket of smog over the past several days, as urban managers faced the public ire over their inaction.
In a meeting held on Friday, Abdolreza Cheraghali a deputy governor general, said the Air Pollution Emergency Committee convened on Saturday to find solutions for curbing air pollution, Mehr News Agency reported.
“The Health Ministry, the University of Medical Sciences and the Department of Environment presented the committee with reports on the situation and pitched solutions. More stringent traffic rules or partial lockdown were among the options,” he said.
Cheraghali noted that December 2020 was one of the most polluted months in Tehran over the past several years and the high level of air pollution is expected to persist until Tuesday.
Charts regularly published by Tehran Air Quality Control Company’s website, Airnow.tehran.ir, illustrate that the capital’s residents inhaled more polluted air in December 2020 compared with the same month of last year.
During the month, Air Quality Index did not enter the range of good air quality even for a single day.
AQI categorizes conditions dictated by a measure of polluting matters into good (0-50), moderate (51-100), unhealthy for vulnerable groups (101-150), unhealthy (151-200), very unhealthy (201-300) and hazardous (301-500).
According to the data, December ended with two consecutive extra polluted days while AQI hit emergency levels.
Monitoring stations in Tehran recorded unhealthy status for all citizens in Dec. 30-31, with the index hovering between 167 and 168.
Air quality was unhealthy for the sensitive group for 23 days in the month, standing between 101 and 150.
This vulnerable group, including the elderly, cardiovascular and respiratory patients, pregnant women and children, was advised to limit their outdoor activities and stay home.
In the six remaining days, the index remained in moderate mode, as AQI did not enter the 50 threshold even for a day.
The AQI review during the year-ago months shows air quality in Tehran is getting worse year by year.
In December 2019, unhealthy air quality was recorded on three days, as the maximum AQI value did not exceed 157.
The vulnerable group was warned to cut their outdoor exposure for 15 days and AQI stood between 51 and 100 for the remaining 13 days, which signifies the moderate mode.
A year earlier, the index value remained below 140 almost throughout December. The rarely-seen good air quality was recorded on only three days. Moderate mode dominated the month, as the index hovered between 51 and 100 for 19 days, and the remaining nine days were unhealthy for the vulnerable group.
Analyses show that the pollutant responsible for the toxic index recorded on all the polluted days was PM2.5—the finest deadly particulate matters released into the air.
Carbon monoxide, nitrogen dioxide, sulfur dioxide, ground-level ozone, PM2.5 and PM10 (atmospheric particulate matters that have a diameter of less than 2.5 and 10 micrometers respectively) are measured to determine air quality. AQI figures are calculated as per the concentration of pollutants.
Heated Dispute
After the coronavirus outbreak forced some businesses to close, many organizations and companies across the board reduced working hours.
Lockdowns have led to a reduction in traffic, as large numbers of employees started working from home while many were laid off. But the extended period of tough restrictions has had little to no positive impact on air quality.
Pollution continues to plague big Iranian cities, especially Tehran, and blame largely fell on worn-out cars and power plants using mazut.
Rains do help curb pollution for a few days, but smog and pollution return soon. As a result, the weatherman continued to appeal to seniors, especially those with pre-existing conditions and kids to stay indoors.
Clunkers, low-quality new vehicles and age-old inter-city buses contribute considerably to air pollution. However, major culprits rarely mentioned by the state broadcaster are the power plants using fossil fuels.
Liquid fuels such as diesel or mazut produce huge volumes of carbon dioxide. Mazut increases the amount of sulfur dioxide in the atmosphere, but even if it is not used in thermal power plants, burning diesel is equally harmful due to the greenhouse gases it produces.
According to TAQCC data, in recent years, the pre-coronavirus reopening of schools and universities from September increased intra-city travel and led to a higher concentration of pollutants such as nitrogen dioxide.
“This year, due to Covid-19, which has closed schools and universities, and classes were held online, it seems that another factor influencing air pollution since autumn is household gas consumption that has forced large industries and power plants to use liquid fuel instead of natural gas as feedstock,” said Hossein Shahidzadeh, TAQCC’s managing director.
“It has pushed up sulfur dioxide levels in the air on some days, especially in the vicinity of polluting industries,” he added.
During the winter months when temperatures are colder and atmospheric inversions are common, combustion emissions from burning fossil fuels, together with the lack of pollutant dispersion under inversions, characterize winter smog formation.
However, Dariush Golalizadeh, deputy director of the National Center for Climate Change at the Department of Environment, says Tehran's power plants have switched to liquid fuels “but they use Euro-4 diesel and not mazut”.
Mohammad Rastegari, a DoE deputy, told reporters that the biggest contributing factor to the suffocating air pollution is PM2.5 particles.
“Incomplete combustion in car and diesel vehicle engines generates a major part of toxic particles that are more hazardous than other sources of pollution, like house heating systems and factories,” he added.
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.
