Multiple sources contribute to indoor pollutant levels. Combustion sources, including cooking and heating, may be significant sources of carbon monoxide, nitrogen oxides (NOx), particulate matter and multiple volatile organic compounds (VOCs). Our group has characterized these sources and the various methods implemented to control indoor pollutant levels (e.g., rangehood efficiency).
Carpet, furnishings and building materials (wallboard, insulation) may also constitute significant indoor pollutant sources, that contribute to long-term background levels of VOCs and semivolatile organic compounds (SVOCs) such as plasticizers and flame retardants. Formaldehyde is an indoor pollutant of concern that is emitted by multiple sources. In recent studies, our group described how hydrolysis of binders used in fiberglass ventilation filters can become a source of formaldehyde upon high relative humidities.
In addition to cooking and smoking, several other occupant activities are associated with increased indoor pollutant levels. For example, in a recent study our group described the impact of using cleaners and air fresheners indoors, considering not only the VOC emissions associated with these household products, but also their reaction with indoor ozone leading to the formation of ultrafine particles and volatile aldehydes.