Respiratory symptoms in older people and use of domestic gas appliances

Background-Studies in children and young women have indicated an increased risk of respiratory illness in association with the: use of domestic gas ap pliances, possibly caused by oxides of nitrogen generated when gas is burne d. It is not known whether risks are similarly increased in older subjects. Methods-A questionnaire about respiratory symptoms in the past year and pot ential risk factors for respiratory disease was mailed to 6000 men and wome n aged 65 years and older who were selected at random from the lists of gen eral practices in North Bristol, UK. Associations between symptoms and the use of gas appliances were examined by logistic regression with adjustment for age, sex, social class, and smoking habits. Results-Questionnaires were completed by 4792 (80%) of those mailed. The mo st common symptoms were exercise induced breathlessness, wheeze, or chest t ightness (51%); wheeze (27%); morning phlegm (20%); and daytime breathlessn ess at rest (19%), In an analysis that included all subjects only weak asso ciations were found with use of gas appliances, odds ratios all being 1.2 o r less. The risks associated with use of a gas hob tended to be higher in w omen, with odds ratios of 1.36 (95% CI 1.01 to 1.83) for wheeze and 1.33 (9 5% CI 0.56 to 3.17) far morning chest tightness, but were lower than had be en reported previously in younger women. Conclusion-The absence of stronger associations cannot readily be explained by bias or confounding. Gas cookers and fires are unlikely to be an import -ant cause of respiratory illness in the elderly. If they do cause such ill ness, the largest risks are likely to be in women who use gas hobs.