The temperature distribution in Phnom Penh was measured using a car to evaluate the thermal characteristics and air pollution in the city. The measurements were made by using temp-hygro sensors with a data logger installed on the car roof and were conducted both during day and night to evaluate the influence of land use. The water temperature was also measured in the River Tonle Sap and the Mekong. By measuring the temperature as a function of distance from the banks of the Mekong and Tonle Sap, the cooling effect of the river was also investigated. Ambient particulates were simultaneously sampled at three different sites in the city along with NO2 and PAHs and heavy metal concentrations were analyzed. The temperature distribution was compared with the concentration of chemical compositions and NO2.
The maximum temperature difference, the so called heat island intensity, was observed during the daytime and was around 4-5°C, and was less than 2°C during the nighttime. The maximum and minimum temperatures respectively were observed in the southern part of the city and the river peninsula between the Tonle Sap river and the Mekong, and a strong cooling effect of river water was found. The water temperature was consistently lower than the ambient and temperature distributions perpendicular to the river and was found to increase with the distance from the riverbank, suggesting that inland areas were cooled to some extent. Comparison of the concentrations of anthropogenic PAHs and NO2 were found to be closely related to temperature.