عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Background & Objective:Formaldehyde is one of the most important aldehydes in ambient air which originates from vehicles and photochemical processes. Because of the importance of this pollutant in public health, in this study, we addressed the concentration level in coupled with daily and cross sectional variation of formaldehyde in the high traffic area of Enghelab Square in Tehran city and also the effect of meteorological parameters on variation of formaldehyde concentration were determined.
Materials & Methods:This cross-sectional study was done in Enghelab Square placed in the district 6 of Tehran in December, January and February (period 1) and April, May and June (period 2) in 2014-2015. To measure the concentration of formaldehyde, the chromotropic acid method was used and samples were analyzed by Perkin Elmer LAMBDA spectrophotometer model of 25 UV/Vis at wavelength 580nm. Data analysing performed by SPSS (T-test and coefficient correlation) and excel ( graphical drawing).
Results:The formaldehyde concentration on Fridays in comparison with other days during the week have a significant difference (Independent T-test, p<0.05). The average concentration of formaldehyde in the period 2 of sampling was higher than that in the period 1 by 6.5 ppb (Paired T-test p<0.05). A significant positive correlation was found between temperature and humidity parameters and formaldehyde’s concentration with correlation coefficients of 0.457 and 0.338 respectively, and also pressure parameter with correlation coefficient of 0.1 showed no significant correlation between formaldehyde concentration variations. Furthermore, formaldehyde concentrations were increased under inversion conditions.
Conclusion:Formaldehyde concentration on Fridays in comparison with other days had lower level that can be resulted from low traffic volume on Fridays. Moreover, increasing formaldehyde concentration in the period 2 (April, May and June months) in comparison to period 1 (December, January and February months) is the result of intensifying photochemical processes in the warm months. Also the effect of temperature, humidity and inversion condition on increasing the concentration of formaldehyde show the importance of meteorological conditions in formaldehyde concentration variations.