Effects of meteorological variables and holidays on the concentrations of PM10, PM2.5, O3, NO2, SO2, and CO in Tehran (2014-2018)

Abstract

Introduction: The aim of this study was to investigate the concentrations

of PM₁₀, PM_2.5, O₃, NO₂, SO₂, and CO in Tehran during March 2014-March 2018, and evaluate the effects of holidays and meteorological parameters on

the air pollution levels.

Materials and methods: Hourly concentrations of PM₁₀, PM_2.5, O₃, NO₂, SO₂, and CO in different air quality monitors of Tehran were acquired. The data from each air quality monitored were validated, and only high-quality monitors were included in this study.

Results: The 4-year averages of PM₁₀, PM_2.5, O₃, NO₂, SO₂, and CO concen-trations were 88.74 (µg/m³), 31.02 (µg/m³), 34.87 (ppb), 71.01 (ppb), 20.04

(ppb), and 3.78 (ppm), respectively. Higher concentrations of PM₁₀ and O₃ were observed during summer. In case of PM_2.5 and CO, autumn and winter concentrations were higher than those in springer and summer. Lower concen-trations of PM₁₀ and NO₂ in Fridays were observed comparing to other days of week. Ozone had high concentrations in Fridays as the weekend in Iran. Except for O₃, all of the pollutants had higher concentrations in the working days, comparing to those in any type of vacation days. Concentrations of all pollutants rather that SO₂ and O₃ in Nowruz holidays were statistically lower than those in the working days. By controlling for the effects of meteorologi-cal variables, our results showed that the air pollution control policies and ac-tions have been not effective for particulate matter.

Conclusion: These results determines the time periods in which the concen-trations of criteria air pollutants are high. This can be very useful for an-nouncing alarms for citizens, and designing the air pollution control plans. In addition, more effective actions should be designed and implemented for reducing ambient levels of particulate matter.