Vertical Distribution of Air Particulate Matter (PM₁, PM_2.5, and PM₁₀) in Different Regions of Tehran

Mass concentrations of particulate matter (PM₁, PM_2.5, and PM₁₀) were observed at different heights (1.5, 3, 9, 15, 18, and 290 m) in Tehran using affordable particulate matter sensors (Plantower PMS5003) to study their vertical distribution. In general, the results showed that the concentration of particulate matter increased with height. The mean concentrations of PM₁ at altitudes of 1−3, 9, and 15−18 m were 33.7 ± 22.4, 36.9 ± 24.7, and 38.2 ± 24.9 µg m⁻³, respectively. Similarly, the mean concentrations of PM_2.5 were 62.9 ± 44.7, 64.4 ± 46.6, and 66.6 ± 45.8 µg m⁻³, respectively. Furthermore, the mean concentrations of PM₁₀ were 73.5 ± 51.2, 76.8 ± 53.4, and 79 ± 53.7 µg m⁻³, respectively. Typically, as height increases, there is a general trend of the PM₁/PM_2.5 and PM₁/PM₁₀ ratios increasing. In contrast, the PM_2.5/PM₁₀ ratio decreases. In addition, the disparity in particulate matter concentration with altitude was more statistically significant during periods when the atmosphere exhibited greater instability. Consequently, the alterations in particulate matter concentrations as altitude increased were statistically more significant during the daytime compared to night-time.