Replacing Gas Stoves With Portable Electric Appliances to Improve Indoor Air Quality and Asthma Control

Cooking on natural gas stoves is a major source of indoor air pollution and may contribute to asthma exacerbations. The investigators recently completed a single-arm trial in which gas stoves were replaced with electric induction stoves in the homes of 85 individuals with poorly controlled asthma. This led to 70% reductions in indoor NO2 levels and clinically important improvements in multiple measures of asthma control. Asthma Control Questionnaire scores improved by 1.1 points in this trial, which is twice as large as the average improvement seen with medical treatment such as inhaled corticosteroids and/or long-acting beta-agonists.

While these results are promising, the trial lacked a control group which limits the causal inferences that can be drawn. In addition, lung function was not directly measured. Moreover, the costs for stove installation and required electrical upgrades averaged nearly $10,000 per home. Most of this cost was related to the older housing stock of trial participants that often required upgrading the entire electrical panel in a house to install a new 240-volt kitchen outlet for the new electric stove. These costs can be a financial challenge for low-income households, limiting the scalability of a potentially effective solution for improving indoor air quality and asthma control.

To address these limitations, the investigators now propose a pilot randomized controlled trial using a delayed crossover design to evaluate the effectiveness of a low-cost intervention to improve indoor air quality, asthma control, and lung function. The investigators will leave gas stoves in place but will instruct participants to preferentially use two relatively inexpensive portable electric appliances that the investigators will provide. Cooking will be done with an electric induction hot plate and baking with an electric toaster oven. Induction hot plates use magnetic coils beneath a ceramic glass surface to send electromagnetic pulses directly to cookware. The investigators will provide induction stove compatible cookware because it is necessary to use cookware that has some steel or iron in order for the energy transfer to work.

The two portable electric appliances and induction cookware are estimated to cost approximately $600 in total and may provide a more affordable option for low-income households. If a household already has a microwave oven, they will be encouraged to use that as well. As the future scalability of the intervention will depend on its usage, the investigators will also evaluate usage and identify facilitators and barriers to consistent use of the portable devices.

• Change in forced expiratory volume in 1 second (FEV1) [Time frame: Baseline assessment 1-2 weeks before portable appliances given to participant. Final assessment 2-3 months after portable appliances given to participant.]