Nine out of 18 air quality monitoring stations in Tehran issued emergency alerts on Wednesday with Tehran Air Quality Control Company (TAQCC) announcing that conditions are expected to worsen in the coming days.
After several days of clean air in the past few months, anticipation of a better year in terms of air quality had grown among Tehranis. However, a blanket of dirty air has now descended on the capital dashing the high hopes.
The spokeswoman for TAQCC, Leila Nazari told ISNA on Wednesday, “Nine out of 18 air quality monitoring stations in the capital have issued emergency alerts. We expect higher air pollution across the city.”
TAQCC releases charts on air quality conditions every day. A glance at the charts shows that in the current month that began on Nov. 22, the air quality index was between 101 and 150 for six days. This marks six days with unhealthy air quality for sensitive groups within two weeks. The eight remaining days of the past two weeks passed with moderate air quality and there were zero clean days.
According to Nazari, on Wednesday morning, the AQI was 144 and was projected to rise during the day. If the index passes the 150 threshold, Wednesday will mark the first day of the current fiscal with air quality ‘unhealthy for all groups’.
The national AQI categorizes conditions based on the amount 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).
Pollutants measured to determine air quality include carbon monoxide, nitrogen dioxide, sulfur dioxide, ground-level ozone and particulate matter (PM2.5 and PM10). The AQI figures are calculated based on the concentration of these pollutants.
In her talk with ISNA, Nazari urged sensitive groups (elderly, pregnant women, children, those suffering from heart conditions and respiratory disorders) to limit outdoor exposure. Residents have been strongly recommended to use public transport.
Experts say the smog can cause fatal asthma attacks and trigger health difficulties for those with respiratory illnesses, kids and the elderly. Annually some 12,000 air pollution-related deaths are reported by the Iranian Legal Medicine Organization, with one-third of the fatalities in the capital.
Main Culprit
Data released by TAQCC shows that PM2.5 (tiny particles or droplets in the air that are 2.5 microns or less in diameter) was the most condensed pollutant in Tehran’s air over the past two weeks.
Last year, during the same two-week period, things were not much different as residents in the capital saw the blue skies for only two days. The AQI stood between 51 and 100 for six days, marking moderate air quality and on the other six days conditions were announced unhealthy for sensitive groups. PM2.5 was again the leading polluting factor during the 14-day period.
Every year with the mercury falling in the fall and cold season, toxic emissions are trapped near to the ground, blanketing the city. Scientists call the phenomenon ‘temperature inversion’.
Although Tehranis have long become used to seeing an opaque sky, and looking at the mountains and the high-rises in the posh northern areas through the haze of air pollution, during the second half of the current fiscal
(started in March), air quality had remarkably improved, especially last month (Oct. 23-Nov. 21). Air quality in the metropolis was not as toxic as it was in the past few years during the same period.
Based on the TAQCC charts, in the month that started on Oct. 23, the capital had 28 days with "moderate" air quality and ended with two days in "good" condition.
Over the Years
A glance at air quality data shows that the density of pollutants has slightly declined in Tehran over the past few years.
During the current fiscal the rapidly expanding capital has experienced comparatively better air quality with 14 days of "good", 209 days of "moderate" and 36 days of "unhealthy for sensitive groups" conditions. Three months of the winter (Dec. 22 – March 20) are normally the most polluted months of the year in Tehran and the data can change drastically.
In the last fiscal, Tehran had 14 days of "good", 234 days of "moderate", and 100 days of "unhealthy for sensitive groups" air quality. The capital saw only eight days with "unhealthy" condition -- a slightly better status compared to the previous year.
In the previous fiscal (March 2016-17), the capital saw nine "unhealthy" days with the AQI fluctuating between 151 and 200. In addition, 80 days were "unhealthy for the sensitive group" and 260 days were "moderate". The capital posted barely 17 days in "good" air condition.
During the fiscal that ended in March 2016, Tehranis experienced one day of "very unhealthy", and five days of "unhealthy" status. Furthermore, the air quality was reported to be "unhealthy for the sensitive group" for 105 days while 233 days were marked as "moderate".
Skies in Tehran and other metropolises are often blanketed with air pollutants with the people and environmentalists pleading for effective pollution mitigation efforts.
While Tehran Municipality has endeavored to address the pollution problem there is a long way to go in curbing the near permanent dilemma in the capital that has expanded rapidly in all four directions and has become ‘home’ to over eight million people.
