Study Of Effects Of Chemical Reactions Initiated By Ozone On Indoor Air Quality

With the continuous increase of outdoor ozone concentration and more and more application of indoor office instruments and ozone generator, indoor ozone pollution has attracted more and more people's attention and been considered a problem. Ozone is a powerful oxidation agent, and the relations between chemistry reactions initiated by ozone and IAQ were studied in this subject. The main contents included the reactions in process of using ozone to eliminate toluene pollutant and the orderliness of ozone removal by HCAC filters.The secondary compounds pollution would be produced in the chemical reactions between ozone and other indoor pollutants. A small-scale chamber experiment was conducted to study the process of using ozone to eliminate toluene. We found ozone did reacted with toluene at a concentration of 25mg/m3, and secondary particle pollution was produced when toluene was oxidated into Benzenecarboxylic acid. The particle distribution between different sizes was observed, and we analyzed the formation process of inhalable particulates as the secondary pollution. The secondary aerosol was mainly fine particles, which was verified by the environmental scanning electron microscope pictures of the particles. Our experiment results indicated that ozone did have some effects to eliminate toluene, but the secondary pollutions were synchronously produced.The effects of chemical reactions between ozone and filter materials and particles captured on indoor air quality were studied on our built test-bed in the study of ozone removal by HVAC filters. The fiters in different environments and at different used time were simulated through sending DOP,A2 dust and black carbon toHVAC fiters. The orderliness of ozone removal by HCAC filters were studied. We found that the efficiency of ozone removal by HVAC filters declined rapidly within 1 hour, and achieved to certain steady-state value. This steady-state value had a strong correlation with the particle species and the quality captured by filters. A HVAC filter contacting surface model was established to analyze the main factors influencing the steady-state value, including the ozone deposition velocity Kd to the surface of the particles, the surface area A of the particles and the air flow volume Q through the filters. The ozone I/O ratio of assumed typical room in summer was predicted through the correlation between efficiencyηand time using ICEM. The ozone removal by filters could regenerate, and we considered the regeneration ability had a correlation with the composition and the nature of the particles. The 0.1-0.3um secondary aerosol was produced in the process of ozone removal by filters, which we considered as a mark of producing a series of other organics pollution through the studies of the mechanism of reactions between ozone and other pollutants. We suggested that the intermittent operation HVAC system should be restarted in 1 hour prior to the occupier entering through our analysis to the oxide producing process and the oxide desorption process.This study is great significant to prevent and decrease indoor ozone secondary pollution.