香烟侧流烟中超细颗粒物释放及衰减特性

Ultrafine particles (UFPs) can penetrate deeply into the lung tissue and cause adverse health effects. In order to investigate the characteristics of concentration and size distribution of UFPs (20~600 nm) in side-stream smoke emitted from cigarettes, environmental chamber experiments and field experiments were carried out. The results showed that the count median diameters (CMDs) and the surface area median diameters (SMDs) during the combustion process were in the ranges of 47.5~66.3 nm and 85.6~100.5 nm respectively, and both of them were still less than 200 nm after 2 hours of decay after combustion. The number and surface area emission rates of different brands of cigarettes were in the ranges of 4.22×10 ¹² ~5.23×10 ¹² particles•min ^-1 and 5.95×10 ¹⁰ ~6.90×10 ¹⁰ μm ² •min ^-1 respectively. Based on these experimental results, decay trends were modeled under various ventilation conditions. The decay rates of UFPs were affected by air exchange rates and environmental conditions. By increasing the air exchange rates from 0.7 (ACH) to 7 (ACH),the time required for the UFP concentration back to that of the background was decreased from more than 3 hours to less than 40 minutes. Moreover, the decay rate was further increased by the particle deposition as shown by the field experiments.