Impact of smoking and candle burning on air concentrations of PCB in a PCB contaminated indoor environment

Long-lasting elevated indoor air concentrations of semi-volatile organic compounds (SVOCs) can cause contamination of indoor surface materials because these compounds have physical-chemical properties causing them to be sorbed (and desorbed) from various surfaces in the indoor environment. Due to this material-gas partitioning and the extensive area of surface materials, the surfaces have the potential to counteract changes in gaseous air concentrations by re-emitting or absorbing SVOCs. In the air itself a partitioning between the gaseous and particulate bound SVOCs exists, relying on among other things the amount and characteristics of the particles. The aim of this study was to investigate the impact of increased particle matter in a contaminated environment, i.e. whether an increase in particles would increase the total air concentration of SVOC through a displacement from the gaseous to the particle phase and at the same time a re-establishment of the gaseous concentration caused by desorption from the surface materials. The study was conducted by measuring the gas and particle bound concentration of SVOCs among a range of congeners of polychlorinated biphenyls (PCBs) in indoor air and quantify the influence of an increased concentration of particulate matter. The experiments were conducted in a room within a dwelling that had elevated levels of PCBs for the last five decades. The increased amount of particulate matter was generated by burning candles and cigarettes, which was measured as particle number concentration and size fractions. Increased cigarette particle concentration increased the indoor air concentration of the sum of all congeners measured by almost 70% compared to background level. Particles from candle burning did not have a similarly significant effect, even though their number concentration was higher. This was likely due to the chemical composition of the particles; cigarette smoke consists primarily of organic particles, while the steady burning of candles produces smaller, mainly inorganic particles. The concentrations of 15 PCB congeners were determined and it was observed that their sorption to cigarette smoke increased with increasing chlorination. A partitioning model indicates absorptive behaviour of PCB to cigarette particles. The results show that smoking inside a residence with long-lasting, elevated PCB concentrations can further increase the concentration of PCB in the air due to its interaction with particulate matter.