Indoor Air 1998; 8: 236–243 Copyright c Munksgaard 1998 Printed in Denmark. All rights reserved INDOOR AIR ISSN 0905-6947 Indoor Environmental Risk Factors for Respiratory Health in Children MARIA H. GARRETT 1 , MICHAEL J. ABRAMSON 2 , BEVERLEY M. HOOPER 1 , PHILIP R. RAYMENT 1 , ROGER P. STRASSER 3 AND MARTIN A. HOOPER 1 * Abstract The indoor environment of 80 houses in the Latrobe Valley, Victoria, Australia was assessed during six visits per- formed bi-monthly over a period of one year. Children between 7 and 14 years of age residing in the houses were included, result- ing in 148 study children, 53 of whom were asthmatic. A respir- atory health questionnaire was completed and skin prick tests performed. Significant risk factors for asthma were: exposure to a gas stove (ORΩ3.15, 95% CI 1.28–7.72), and indoor pets (ORΩ 2.68, 95% CI 1.07–6.70). Exposure to airborne Aspergillus spores (π10 CFU/m 3 , ORΩ1.51, 95% CI 1.05–2.18) was a risk factor for atopy, while exposure to a gas stove (ORΩ2.32, 95% CI 1.04–5.18) was a risk factor for respiratory symptoms. In conclusion, ex- posure to gas stoves, fungal spores and pets in the home were identified as statistically significant risk factors for respiratory health in children. Key words Asthma; Respiratory symptoms; Nitrogen dioxide; Fungal spores; Formaldehyde; House dust mites. Received 17 July 1998. Accepted for publication 1 September 1998. C Indoor Air (1998) Introduction The prevalence of asthma is increasing throughout the western world (Bousquet et al., 1993), and as many as 30% of all Australians suffer from asthma at some stage in their lives (National Asthma Campaign, 1996). In fact, Australia has one of the highest prevalence rates of asthma in the world (Robertson et al., 1993). The reasons why asthma is becoming more common throughout the western world are not well understood, and it is not known why the disease is so common in Australia compared to other countries. It has, however, been suggested that indoor environmental factors may 1 School of Applied Sciences, Monash University, Churchill, Victoria 3842, Australia, Fax: π61 3 5122 6738, Tel: π61 3 5122 6450, E-mail: Martin.Hooper/- sci.monash.edu.au, 2 Department of Epidemiology & Preventive Medicine, Monash Medical School, Alfred Hospital, Prahran, Australia, 3 Monash Centre for Rural Health, Latrobe Regional Hospital, Moe, Australia, *Author to whom correspondence should be addressed contribute to both the general increase in asthma prevalence worldwide (Burney et al., 1990), and to Australia having such a high prevalence compared to other countries (Robertson et al., 1993). If this is the case, then we must identify which indoor factors are responsible for the deteriorating respiratory health of children in order to build healthy homes for the future. Previous research has successfully identified tobacco smoke and excessive allergen exposure as risk factors for asthma and changed housing conditions are men- tioned as a possible reason for increased allergen ex- posure (Utell and Looney, 1995). However, the results for many other contaminants are inconclusive or limited, making recommendations difficult. The com- plexity and variability of asthma aetiology leads to complex research methods being required in order to distinguish between the effects of various factors. For this reason it has been suggested that multi-contami- nant studies are useful in research involving asthma and related diseases and the indoor environment (Sa- met, 1995). The present paper presents the results from such a study where a detailed characterisation of the home environment is combined with an evaluation of respiratory health outcomes in children. Materials and Methods A total of 80 households in the Latrobe Valley, Victoria, Australia were recruited for the study as volunteers from local primary schools, doctors and advertise- ments in the local press. All participating households had at least one child in the age-group 7 to 14 years. Forty-three of the participating households had at least one asthmatic child, diagnosed by a doctor, in the age-