Sarah Free – Master's 2008


To determine whether more effective home heating can reduce school absence.


New Zealand homes are under-heated by international standards, with average indoor temperatures still lower than the WHO recommended minimum of 18C. Also of concern are the social disparities that exist, with low income households more likely to be using ineffective heating or no heating at all.  Research has highlighted the connection with low indoor temperatures and adverse health outcomes especially for children with asthma, and has also highlighted the ways in which living in an under-heated home can adversely impact on the social functioning and psychological well-being of family members.  Both health effecs and psycho-social effects can impact on school absence.


This study used a single-blinded randomised controlled trial design to collect information on 615 children living in 409 households.  The inclusion criteria for each household were that there was at least one child aged 7-12 years in the household who had doctor-diagnosed asthma (the “index” child) and that the main form of heating used was an open fire, plug-in electric heater, or un-flued gas heater. the intervention was the installation of a more effective heater of at least 6kW in 200 randomly selected households prior to the winter of 2006 , with the remaining households receiving their heaters at the conclusion of the study.

The temperature and NO2 levels in the living room and the index child’s bedroom were recorded throughout the study period.  Questionnaires were used to collect information both before and after the intervention on each child’s age, gender, ethnicity, general health, asthma symptoms, days absent from school for illness, household income, the use of other gas appliances in the home and smoking behaviours.  Each child’s school was contacted directly and term-by-term absence information obtained for 2006 and previous years where available.  Schools were asked about the 4 types of heating use in the children’s classrooms and this information was verified for a small subset of schools by personal visit.

Statistical Analysis

Data were analysed using generalised linear models in R [version 2.4.1], with the quasi-Poisson link. The main analysis used data from the index children only to to avoid clustering by households.  A separate analysis was done for siblings.


 High quality data was obtained for 269 out of 409 index children.  The study showed that more effective heating in the homes of these asthmatic children resulted in a significant (p=0.02) reduction of 21 percent in the average number of days off school. For the index children in households previously using un-flued gas heating, more effective heating resulted in a significant (p=0.01) reduction of 28% in the average number of days off school.


The installation of more effective and non-polluting heating needs to be considered a priority for all New Zealand households, but especially those with asthmatic children.  Consideration needs to be given as to how to best overcome barriers that currently prevent low income households and those who are renting from accessing better heating.