Combustion activities such as cigarette smouldering, incense burning and cooking are important sources of particulate matters (PM) in indoor environments. Vacuum cleaning contributes to the non-combustion-related sources of PMs. In this study, we investigated the rates at which ultrafine particles (UFPs) are emitted from cigarettes, incenses and vacuum cleaners in a small test chamber. UFP emission from cooking was obtained by conducting experiments in a residential kitchen. Particle number concentrations and size distributions from these sources were measured using a scanning mobility particle sizer (SMPS) and the UFP emission rates were then determined using a material balance approach. The mean UFP emission rates of cigarette smouldering and incense burning were found to be 3.36 ± 0.34 and 0.44 ± 0.33 × 1011 particles min−1 in terms of the number emission rate, or 22.78 ± 1.21 and 3.48 ± 2.98 × 1015 nm2 min−1 in terms of the surface area emission rate, respectively. Vacuum cleaner motor operation and cooking showed high variations in UFP emission, in the ranges 0.013–0.066 and 4.70–148.29 × 1011 particles min−1, respectively. A database of emission rates for UFP sources can be compiled, which will be useful in estimating the UFP concentration and subsequent human exposure.

Experimental studies on the removal of accumulated environmental tobacco smoke (ETS) and the effectiveness of ETS leakage control were carried out in a model smoking room using carbon monoxide, nicotine, 3-ethenylpyridine, respirable suspended particulates, and ultrafine particles (UFP) as the ETS tracers. The study investigated the effectiveness of the designated smoking room, equipped with a displacement ventilation system under different ventilation rates (10-58 L/sec per person,) in removing the ETS tracers. The extent of ETS leakage through different door operating scenarios under various ventilation rates was intensively studied. In particular, a manikin installed on a motorized rail was used to study the effect of human movement on the leakage of the ETS tracers. A double-door anteroom design was incorporated into the smoking room to study its effectiveness in ETS leakage prevention. It shows that at least 5 Pa of negative pressure, a fresh air supply rate 3-5 times higher than a typical office, direct air exhaust without air recirculation, and keeping the door closed are important for reducing ETS leakage. However, with the smokers moving in and out and the opening of the door, noticeable leakage of ETS can occur. The double-door anteroom design can improve leakage prevention. Among the five tracers, nicotine required the longest purging time to remove, after the smoking activity was stopped in the smoking room, due to its highly sorptive property. At least 4.4-6 hr of purging is needed for minimizing ETS exposure by non-smokers entering the smoking room. The peak size of particulate matter inside the smoking room is about 80-100 nm, suggesting the importance of including UFP as an indicator for monitoring the exposure and leakage of ETS. The impact of manikin movement on contaminant transport was studied, providing useful information on the effects of human activities on indoor air quality multicompartmental modeling.

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