Abstract
Background: The fractional concentration of exhaled nitric oxide (FENO) is a non-invasive measure of poor asthma control. The indoor environment presents a complex array of pollutant exposures, which must be characterized to isolate the effects of a single pollutant on asthma morbidity. Aims:To quantify the effects of indoor PM2.5 and formaldehyde (FA) on FENO after controlling for the effects of pollutants emitted from similar sources (second hand smoke [SHS] and outdoor PM2.5). Methods:We measured indoor PM2.5 and FA over a five-day sampling period in the homes of 95 asthmatic children in the Green Housing Study. In multivariate regression models, we controlled for exposure to SHS and outdoor PM2.5 using urinary cotinine concentrations and outdoor PM2.5 measurements from central site monitors. Results:In preliminary bivariate analysis, neither indoor PM2.5 nor FA was associated with FENO. In multivariable analysis, controlling for SHS increased the effect estimate of PM2.5, and this association was statistically significant in a model which also controlled for outdoor PM2.5 and restricted to children not on corticosteroids (0.99% change in FENO per ?g/m3 increase of PM2.5 [95% CI: 0.09, 1.91]). For FA, adjusting for outdoor PM2.5 resulted in an effect estimate that was marginally significant (1.04% change in FENO per ?g/m3 increase of FA [95% CI: -0.13, 2.23]), but adjusting for SHS had no effect. Conclusions:The observed association between individual indoor pollutant exposures and FENO may be confounded by co-exposure to SHS or outdoor pollutants. This analysis found that the association between indoor PM2.5 and FENO was negatively confounded by SHS, a source of indoor PM2.5. Adjusting for SHS did not modify associations with FA, suggesting that SHS is not a major FA source in our study homes. These relationships help reveal important indoor air pollution sources. Significant effects from PM2.5 were only seen in children not on inhaled corticosteroid therapy, revealing the complex interplay between asthma triggers and treatment.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
