Design and Characterization of a New Quartz Smog Chamber System for Studying the Atmospheric Effects of Vehicle Emissions on Plateaus

Abstract

Since the 1960s, smog chambers have been an important tool for studying air pollution, and many indoor and outdoor smog chambers have been developed both domestically and internationally. However, all of these chambers are located at altitudes below 1500 meters, only simulating atmospheric conditions in low-altitude plains. Moreover, most are made of polytetrafluoroethylene (PTFE), resulting in a higher wall deposition effect. To simulate the evolution of atmospheric pollution in high-altitude regions, we developed the world's highest-altitude quartz smog chamber, located in Kunming at an elevation of 1900 meters. The chamber is a 3.375m³ cube constructed from 5mm quartz glass and features controlled temperature (0°C to 40°C) and relative humidity (2%-95%). We conducted a comprehensive characterization of the chamber, including tests for temperature and humidity stability, mixing stability, pressure resistance and sealing, light intensity measurement and environmental light matching, and background pollutant and wall loss assessments. The characterization results indicate excellent performance in simulating sunlight and controlling background pollutants. The NO2 photolysis rate is adjustable, ranging from 2.03×10⁻³s⁻1 to 5.87×10⁻³s⁻1. Under dry conditions, after 6 hours of photooxidation, the detected O3 formation rate was approximately 1.05 ppb/h, with a particulate mass concentration around 0.12 μg/m³. The reactor withstands pressures exceeding 1.5 bar, and at this pressure, the leak rate was measured at 1.1‰. Validation using the toluene-NO₂ system showed that indoor mixing reached equilibrium in about four minutes. The wall loss rate for SWFU-HAP particles at 25°C and RH <10% was 0.066 h⁻1, which is 70% lower compared to other chambers, while at RH = 50%, the wall loss rate was 0.137 h⁻1. These results demonstrate the superior performance of our system, meeting the high standards required for high-altitude vehicle exhaust aerosol emissions research and the investigation of the formation mechanisms of vehicle exhaust in high-altitude atmospheric environments.