Laboratory study of the impact of evaporative coolers on indoor PM concentrations

Evaporative cooling is used extensively in low humidity areas of the Southwest United States desert region and throughout other dry climate areas worldwide for residential thermal comfort. A literature review suggested the possibility of evaporative cooling increasing personal exposures to particulate matter along with increased incidences of respiratory illnesses. Indoor and outdoor particulate matter concentrations have been measured to determine the effects of evaporative cooling on ambient air in an evaporative cooler test chamber. The test chamber experiment was conducted to better evaluate the impact of evaporative cooling without interference by household activities such as cooking, cleaning, smoking, etc. Measurement of particulate matter was performed with tapered element oscillating microbalance (TEOM) instruments to provide a larger number of data points for comparison. Based on the experiments performed on two popular models of evaporative coolers, it was found that the evaporative cooler reduces indoor PM10 by approximately 50%, and has a varying reduction effect of between 10 and 40% on PM2.5. These findings are consistent with the predicted outcomes suggested by particulate matter deposition models.