In the Western world the role of air pollution in the initiation of respiratory disease in children is contentious 1. There is good evidence that air pollution can trigger symptoms in susceptible children but its contribution to the pathogenesis of childhood respiratory disorders, such as asthma, remains unclear. There has been considerable interest in traffic-related pollutants and studies have investigated the prevalence of asthma and wheeze in children living near main roads 2–4. While this remains an important area of research, there is also concern about exposure to air pollutants in the indoor environment. In developed countries, people spend most of their time indoors and in the case of many air pollutants, the indoor environment is the principal source of exposure. For young children, the most important indoor environment is the home. On average, children spend ∼15 h a day indoors at home 5. Infants average nearly 20 h per day indoors 6. Indoor air pollutants, such as environmental tobacco smoke (ETS), nitrogen dioxide and formaldehyde, have been associated with adverse respiratory health outcomes in children 7. In recent times, there have been concerns about domestic exposure to volatile organic compounds (VOCs) and other air toxics. Indoor air toxics, including VOCs, are emitted from a broad range of sources, including cleaning agents, furnishings, paints, cosmetics, aerosol sprays and pesticides. These products also contain chlorine, ammonia, surfactants, acids, bases and oxidants, and reactions between compounds can create highly irritative secondary pollutants 8. The health effects of this chemical mix, at concentrations normally encountered in homes, is not yet known but there is some evidence that these exposures may be associated with wheeze 9–11 and allergy 12 in young children. The data, however, …