Number of Participants:
Lifestage of Participants:
Youth (1-18 years, specifically 5-11 years of age)
Nitrogen dioxide (NO2), Household allergens
The STAR study examined the role of exposures to indoor allergens and indoor and outdoor nitrogen dioxide (NO2) on the severity of asthma. The study enrolled approximately 1,400 asthmatic children ages 5-11 years old from urban and suburban Connecticut and Massachusetts between 2006 and 2009. This study led to an intervention trial to test the efficacy of indoor air cleaners in reducing NO2 exposure and improving health in asthmatic children.
Related NIEHS-Funded Projects
Projects listed supported initial development of the epidemiological resource, added study participants, collected additional information or samples from study participants, and/or used samples or datasets derived from the resource.
Indoor Nitrogen Dioxide Exposure and Children with Asthma: An Intervention Trial
Leaderer, Brian P (Contact); Bracken, Michael B; Gent, Janneane Ferguson; Holford, Theodore R
Most Recent Award Year:
Lifestage of Participants:
Exposure: Youth (1-18 years, specifically 5-11 years of age); Assessment: Youth (1-18 years, specifically 5-11 years of age)
Nitrogen dioxide (NO2), Particulate matter
Passive air sampling of nitrogen dioxide (NO2)
Other Participant Data:
Genes or Other DNA Products Studied:
Epigenetic Mechanisms Studied:
Asthma and reactive airway disease are the most common chronic medical conditions in children and affect over 7 million in the US alone. Asthma prevalence tends to be highest in inner cities and has a disproportionate impact on minorities. Adverse respiratory effects in children with asthma are associated with exposures to nitrogen dioxide (NO2) - an air pollutant with both indoor and outdoor sources. Principal indoor sources include gas stoves as well as other gas appliances, natural gas-fueled home heating, and infiltration from outdoor sources (e.g., traffic). Over one-third of US households use gas for cooking, and in homes with sources, highest indoor NO2 concentrations are found in inner-city residences where gas service is common and house volumes are smaller compared to suburban homes. Data from epidemiologic studies indicate that a reduction in NO2 concentrations commonly encountered in urban homes would result in a clinically significant reduction in asthma severity. We propose a randomized, double-blind, triple cross-over intervention study to examine the efficacy of substantial reduction of indoor NO2 on reducing asthma severity. To carry out an optimal Phase III clinical trial (randomized, double-blind, cross-over), we have designed an air cleaning device to accommodate each one of three filter types: (1) an NO2 scrubber composed of a filter that removes 80% of NO2 and also 80% of particles; (2) a HEPA filter that removes all suspended particulate matter > 0.12 microns (but removes less than 10% of the NO2); and (3) a "control" that filters neither NO2 nor particles. We propose to enroll 600 asthmatic children between 5-11 years of age living in homes with gas stoves and high NO2 levels and to randomly allocate them to a sequence of three experimental home interventions over an 18-week period while following them to assess asthma severity. Pilot testing suggests that two air cleaning devices operating at flow rates on the order of 450 cubic feet per minute, each with the NO2 scrubber in place, will ensure reductions in NO2 in a modest-sized home on the order of 90% or greater. The primary study outcome is a 5-level asthma severity score (Global Initiative for Asthma guidelines), calculated using symptoms, asthma medication use (recorded on calendars). The research aims are: (1) Determine whether reducing exposure to NO2 and particles compared to a "control" (non-filtered) condition results in a clinically significant reduction in asthma severity by one or more levels; and (2) Determine whether reducing exposure to particles > 0.12 microns alone (without concurrent reduction in NO2) similarly reduces asthma severity. We focus recruitment efforts on asthmatic children from urban families most likely to have high indoor levels of NO2 (e.g., families with gas stoves living in multifamily housing). If trial results indicate that children with asthma would benefit from a reduction in exposure to indoor NO2, practical and economical remediation strategies are readily available.
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