Because over 80% of our time is spent indoors, we are significantly influenced by the air we breathe in the indoor environments in which we spend our time. The indoor air environment is not an exact reflection of outdoor conditions. There are many unique characteristics and activities that happen indoors including cigarette smoking, cooking, building material emissions, and consumer product use, which are examples of determinants of indoor but not outdoor air quality. Table 17.1 summarized the typical air pollutant concentration in indoor environments. The main factors that influence the quality of the air we breathe indoors are:
- Hazardous pollutants emitted both indoors and outdoors.
- Meteorology and climate, which modifies both outdoor air pollution and the indoor environment.
- Building ventilation conditions including infiltration, natural ventilation, and mechanical ventilation.
- Pollutant decay and removal processes in indoor air and on surfaces.
Table 17.1 Typical indoor pollutant concentrations.
Source: Adapted from Wadden and Scheff (1983).
|Carbon monoxide||2.5–28 ppm||Offices, restaurants, bars|
|Nitrogen dioxide||0.005–0.317 ppm||Homes with gas stoves|
|Respirable particles||100–700 μg m−3||Smoking restaurants, residences|
|20–60 μg m−3||Nonsmoking restaurants, residences|
|Total suspended particles ...|