More effective home heating reduces school absences for children with asthma.

BACKGROUND: New Zealand homes are underheated by international standards, with average indoor temperatures below the WHO recommended minimum of 18 degrees C. Research has highlighted the connection between low indoor temperatures and adverse health outcomes, including social functioning and psychological well-being. Both health effects and social effects can impact on school absence rates. The aim of this study was to determine whether more effective home heating affects school absence for children with asthma. METHODS: A single-blinded randomised controlled trial of heating intervention in 409 households containing an asthmatic child aged 6-12 years, where the previous heating was an open fire, plug-in electric heater or unflued gas heater. The intervention was the installation of a more effective heater of at least 6 kW before the winter of 2006 in half the houses. Demographic and health information was collected both before and after the intervention. Each child's school was contacted directly and term-by-term absence information for that child obtained for 2006 and previous years where available. RESULTS: Complete absence data were obtained for 269 out of 409 children. Compared with the control group, children in households receiving the intervention experienced on average 21% (p=0.02) fewer days of absence after allowing for the effects of other factors. CONCLUSION: More effective, non-indoor polluting heating reduces school absence for asthmatic children.

Retrofitting houses with insulation: a cost-benefit analysis of a randomised community trial.

BACKGROUND: Housing is an important environmental influence on population health, and there is growing evidence of health effects from indoor environment characteristics such as low indoor temperatures. However, there is relatively little research, and thus little firm guidance, on the cost-effectiveness of public policies to retrospectively improve the standards of houses. The purpose of this study was to value the health, energy and environmental benefits of retrofitting insulation, through assessing a number of forms of possible benefit: a reduced number of visits to GPs, hospitalisations, days off school, days off work, energy savings and CO(2) savings. METHODS: All these metrics are used in a cluster randomised trial--the "Housing, Insulation and Health Study"--of retrofitting insulation in 1350 houses, in which at least one person had symptoms of respiratory disease, in predominantly low-income communities in New Zealand. RESULTS: Valuing the health gains, and energy and CO(2) emissions savings, suggests that total benefits in "present value" (discounted) terms are one and a half to two times the magnitude of the cost of retrofitting insulation. CONCLUSION: This study points to the need to consider as wide a range of benefits as possible, including health and environmental benefits, when assessing the value for money of an intervention to improve housing quality. From an environmental, energy and health perspective, the value for money of improving housing quality by retrofitting insulation is compelling.

Sources of nitrogen dioxide (NO2) in New Zealand homes: findings from a community randomized controlled trial of heater substitutions.

UNLABELLED: Houses in New Zealand have inadequate space heating and a third of households use unflued gas heaters. As part of a large community intervention trial to improve space heating, we replaced ineffective heaters with more effective, non-polluting heaters. This paper assesses the contribution of heating and household factors to indoor NO2 in almost 350 homes and reports on the reduction in NO2 levels due to heater replacement. Homes using unflued gas heaters had more than three times the level of NO2 in living rooms [geometric mean ratio (GMR) = 3.35, 95% CI: 2.83-3.96, P < 0.001] than homes without unflued gas heaters, whereas homes using gas stove-tops had significantly elevated living room NO2 levels (GMR = 1.42, 95% CI: 1.05-1.93, P = 0.02). Homes with heat pumps, flued gas heating, or enclosed wood burners had significantly lower levels of NO2 in living areas and bedrooms. In homes that used unflued gas heaters as their main form of heating at baseline, the intervention was associated with a two-third (67%) reduction in NO2 levels in living rooms, when compared with homes that continued to use unflued gas heaters. Reducing the use of unflued gas heating would substantially lower NO2 exposure in New Zealand homes. PRACTICAL IMPLICATIONS: Understanding the factors influencing indoor NO2 levels is critical for the assessment and control of indoor air pollution. This study found that homes that used unflued gas combustion appliances for heating and cooking had higher NO2 levels compared with homes where other fuels were used. These findings require institutional incentives to increase the use of more effective, less polluting fuels, particularly in the home environment.

Retrofitting houses with insulation to reduce health inequalities: aims and methods of a clustered, randomised community-based trial.

This paper describes the purpose and methods of a single-blinded, clustered and randomised trial of the health impacts of insulating existing houses. The key research question was whether this intervention increased the indoor temperature and lowered the relative humidity, energy consumption and mould growth in the houses, as well as improved the health and well-being of the occupants and thereby lowered their utilisation of health care. Households in which at least one person had symptoms of respiratory disease were recruited from seven predominantly low-income communities in New Zealand. These households were then randomised within communities to receive retrofitted insulation either during or after the study. Measures at baseline (2001) and follow-up (2002) included subjective measures of health, comfort and well-being and objective measures of house condition, temperature, relative humidity, mould (speciation and mass), endotoxin, beta glucans, house dust mite allergens, general practitioner and hospital visits, and energy or fuel usage. All measurements referred to the three coldest winter months, June, July and August. From the 1352 households that were initially recruited, baseline information was obtained from 1310 households and 4413 people. At follow-up, 3312 people and 1110 households remained, an 84% household retention rate and a 75% individual retention rate. Final outcome results will be reported in a subsequent paper. The study showed that large trials of complex environmental interventions can be conducted in a robust manner with high participation rates. Critical success factors are effective community involvement and an intervention that is valued by the participants.