Seasonal variations and exposure levels of carbon monoxide in a naturally ventilated residential underground parking lot

Abstract

Underground residential parking lots have recently become prevalent in China. Carbon monoxide is one of the major pollutants in underground parking lots, and the risk of exposure to carbon monoxide is closely associated with the health of vehicle owners, workers, and garage security officers. For the present article, the authors evaluated the seasonal variation of carbon monoxide in a naturally ventilated underground residential parking lot during 1 year of continuous field measurements. The influences of traffic flow and air-exchange rate on carbon monoxide concentration were determined based on measurement data. The result showed a significant seasonal diurnal pattern of carbon monoxide concentration, with the maximum in winter and minimum in summer. Daily mean carbon monoxide concentration in the parking garage was below the long-term (8 h) carbon monoxide exposure limit in parking lots from the World Health Organization (25 ppm) in summer, autumn, and spring; while more than 90% of the measurements exceeded the World Health Organization long-term (8 h) exposure limit in winter. An air-exchange rate of 0.12 or 1 h−1 would ensure that the carbon monoxide concentration remained below the 25 or 15 ppm limit, respectively. During the measurements, the carbon monoxide concentration seemed to vary linearly under the combined effect of traffic flow and natural ventilation.