| Abstract: | Abstract Humidifiers, used in approximately 25% of Canadian homes, may potentially aggravate asthma by increasing the airborne concentrations of fine particles and microbials. A randomized controlled study was carried out to investigate the acute effects of humidifier use on asthma control. Daily peak flows, asthma symptoms and need for medication were assessed during 2 weeks (period 1) when 110 subjects were using humidifiers and during the following 3 weeks (period 2) when half of the subjects were randomized to stopping the humidifier and the other half to continuing its use. In the intervention group, mean morning peak flows were 357 L/min (SEM 17) during humidifier use (period 1) and 352 L/min (SEM 16) when humidifiers were not used, a difference of - 4.4 L/min (95%CI - 11.2 to 2.3) (period 2). Respective values in the control group were 403 L/min (SEM 16) during period 1 and 405 L/min (SEM 16) during period 2. No significant differences were found when analyses were restricted to portable humidifiers, allergies to mites and/or molds, and infrequently cleaned humidifiers. Humidifiers cause no short-term adverse health effects in the majority of those with asthma. Future studies should address the broader question concerning the chronic effects of increased home humidity on microflora and health. |
