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.

Risk factors for mold in housing: a national survey.

UNLABELLED: A national random telephone survey was undertaken to determine the prevalence of reported mold in New Zealand houses and the risk factors for it. A total of 613 households provided responses. Mold in one or more rooms was reported by 35.1% of respondents in the sample. House design and construction factors that were independently associated with reported mold in the multivariate analysis included: poorer house condition, older house age (>22 years), relative lack of sun exposure, and having no insulation (e.g. for poorer house condition: odds ratio=1.97, 95% CI=1.25, 3.11). Univariate analyses also showed increased risk associated with high locality rainfall, and living in the most northern part of the country. The number of residents was significantly associated with reported mold in the multivariate analysis as were various behaviors in the univariate analysis (i.e. frequency of baths, showering and clothes washing). The high prevalence of unflued gas heating (32.9%) found in this sample is of potential concern given the potential respiratory hazards. Although this survey has a number of limitations, it does suggest that there are a number of potentially modifiable risk factors for mold that could be reduced by a range of policy responses. PRACTICAL IMPLICATIONS: While further research is desirable, the available evidence associated with the health and other adverse impacts of both mold and dampness would favor additional policy responses by government. These could include changes to regulations around housing design including house position, access to sunlight, and level of insulation. The extension of low interest loans for insulation or subsidized installation can help to increase its level of use. Restrictions on the sales of unflued gas heaters could also be considered. A mass media campaign could also be used to inform the population of the readily modifiable risk factors for mold growth and dampness.