31. Field Study on PM1 Air Pollution in a Residential Underground Parking Lot

PM1 (fine particles with a diameter smaller than 1 μm) number concentrations are more straightforward compared with particle mass concentrations for air quality assessment in underground parking lots. PM1 number concentrations, hourly vehicle passages, real-time temperature, relative humidity, and real-time velocity in the entrance and exit cross sections were measured over the course of one week in May at a residential underground parking lot in Harbin. The daily peak and total number of vehicle passages are much less than those in a commercial underground parking lot. PM1 concentrations were found to be higher in the morning and evening and lower at both weekends and nonpeak traffic times, such as outside of rush hour. During weekdays, the peak-to-trough deviation and daily average value of PM1 concentrations were, respectively, 1.4 and 1.5 times higher than the concentrations during weekends. The vehicle passages per hour and the velocity and temperature per hour in the entrance and exit cross sections had the greatest impact on the PM1 concentration. These findings indicate that PM1 pollution in residential underground parking lots can reach serious levels.