Tobacco smoke particles and indoor air quality (ToPIQ) - the protocol of a new study

The supply of clean air is regarded as one of the most important basic factors for the human health and wellbeing. In consequence, polluted air is able to threat human health and is considered as a major global health problem [1]. According to an estimation of the WHO (World Health Organization) approximately 2 million premature deaths worldwide per year are caused by air pollution [2]. Especially the quality of indoor air is of utmost importance for human health. Not only because people spend most of their time indoors (in industrialized countries, as the USA, up to almost 90 percent [3]) but also because the indoor concentration of pollutants is often much higher [4]. The wide range of indoor pollutants contains organic or inorganic chemicals, biological aerosols (bioaerosols) and particles. A major source of indoor air pollution is the environmental tobacco smoke (ETS, also called second hand smoke) [5-7], which is a mixture of exhaled mainstream smoke (MS) and sidestream smoke (SS) released from the smouldering tobacco product. Since decades it is well documented that ETS can be harmful to human health and causes premature death and disease to the non-smoking population [8]. Especially ETS exposed children have an increased risk for acute respiratory infections, sudden infant death syndrome, more severe asthma and ear problems [6,8]. In the adult population, exposure to ETS is associated with acute coronary heart disease [9-11] and lung cancer [12,13]. According to a 2004 published estimation by ？berg et al., almost half of the world's children (approx. 40%) are regularly exposed to ETS followed by nonsmoking women (35%) and men (33%) [14]. Although exposure to ETS appears to present smaller risks than active smoking, the large percentage of exposed people, coupled with evidences that ETS causes illness and premature death, demonstrates a substantial public health threat. Because of these adverse effects to human health, tobacco smoke has been intensely investig