Asthma is one of the most prevalent chronic diseases of childhood. Because children spend many hours indoors at home, interventions to decrease asthma-exacerbating exposures in the home could have profound impacts. In addition, many pollutants, such as fine particulate matter (PM2.5) and Nitrogen dioxide (NO2) have higher levels indoors than outdoors, even in the developed world. Air pollutants may worsen asthma symptoms through multiple mechanisms, including by directly increasing airways inflammation. One of the primary sources of indoor pollutants in the United States is cooking with gas stoves, and cooking-related pollutants have been shown to be related to increases in asthma symptoms. In a nationally representative sample, children who live in homes where cooking ventilation is not used have higher rates of asthma and other respiratory diseases. This study will be a pilot stepped-wedge randomized trial in homes with both a child with asthma and a gas stove, assessing an intensive cooking ventilation intervention. The long-term goal is to provide the scientific rationale for an easily implementable household air pollution intervention. The primary aim of this project will be to assess the effect of the cooking ventilation intervention on household PM2.5 and NO2 levels, and a secondary aim is to assess the effect of the cooking ventilation on short-term measures of pediatric asthma control, as improvements could result either from changes in PM2.5 and NO2 or from changes in other chemicals. As a youth participatory action research project, a third aim will be to develop scientific leadership capacity in community youth. This will be the first trial to both replace stove hoods for improved cooking ventilation in the homes of children with asthma and objectively measure both stove and hood fan use. Moreover, the stepped wedge design will allow for analysis in two ways: first as a randomized controlled trial (to minimize confounding) and secondly as a before-after trial (to maximize sample size). All homes will receive measurement of air flow through the range hood, and an intervention with two parts: (1) replacement of the range hood if air flow is less than the California building code level of 100 cubic feet per minute (cfm) or intolerably noisy and (2) intensive education regarding the use of the range hood during all cooking events and cleaning of the grease screen. A manufacturer (Broan), which has no role in the design of the study, plans to provide replacement hoods if the airflow is inadequate. Stove and Range hood sensors will also be installed in participant homes for the entire 3-week data collection period, with study visits at initiation and every week thereafter, for a total of four visits spanning three weeks of data collection. Those randomized to group 1 (30 homes) will receive the intervention after one week of baseline data collection and group 2 (30 homes) will receive it after two weeks. Measured variables will include stove use, range hood use, PM2.5 and NO2 in the household, and multiple measures of asthma control in the children (spirometry, Fractional exhaled Nitric Oxide, asthma control questionnaire, ISAAC Asthma and Environmental Questionnaires).
This trial will rigorously study whether improving cooking ventilation over gas stoves in the homes of children with asthma can lead to a reduction in household air pollution exposure. This may provide early evidence for an easily implementable intervention to reduce household air pollution, which can contribute to asthma symptoms in children with asthma. An added benefit of this intervention is that it will engage youth from a low resource community.
