Chemical Reactions in the Indoor Atmosphere
This chapter summarizes the key chemical reactions that occur in indoor air. Indoor air chemistry has many similarities to, but also some differences from, that in the ambient atmosphere. Indoors, there is less light, more available surface area and a time scale for reaction that is limited by the exchange rate with outdoors. Despite these differences, there is still a wide range of gas-phase and surface reactions and also partitioning between gas and particle phases. Consequently, indoor chemical reactions produce a myriad of complex, multifunctional products, many of which are thought to be harmful to health. Most research in this area has been focused on the reactions between ozone and terpene species. Ozone can ingress from outdoors, whereas terpenes are components of many indoor products such as cleaning fluids, air fresheners and fragrances. These reactions lead to a wide range of both short- and longer-lived species. Research is becoming increasingly focused on the impact of human activities such as cooking and cleaning on indoor air chemistry. The importance of surfaces is also becoming apparent, both in terms of providing a permanent or temporary sink for species that undergo deposition, but also as a means of forming new products.