title: Home interventions are effective at decreasing indoor nitrogen dioxide concentrations.
abstract: Nitrogen dioxide (NO2 ), a by-product of combustion produced by indoor gas appliances such as cooking stoves, is associated with respiratory symptoms in those with obstructive airways disease. We conducted a three-armed randomized trial to evaluate the efficacy of interventions aimed at reducing indoor NO2 concentrations in homes with unvented gas stoves: (i) replacement of existing gas stove with electric stove; (ii) installation of ventilation hood over existing gas stove; and (iii) placement of air purifiers with high-efficiency particulate air (HEPA) and carbon filters. Home inspection and NO2 monitoring were conducted at 1 week pre-intervention and at 1 week and 3 months post-intervention. Stove replacement resulted in a 51% and 42% decrease in median NO2 concentration at 3 months of follow-up in the kitchen and bedroom, respectively (P = 0.01, P = 0.01); air purifier placement resulted in an immediate decrease in median NO2 concentration in the kitchen (27%, P < 0.01) and bedroom (22%, P = 0.02), but at 3 months, a significant reduction was seen only in the kitchen (20%, P = 0.05). NO2 concentrations in the kitchen and bedroom did not significantly change following ventilation hood installation. Replacing unvented gas stoves with electric stoves or placement of air purifiers with HEPA and carbon filters can decrease indoor NO2 concentrations in urban homes.
  
  
  CONCLUSIONS
  Several combustion sources unique to the residential indoor environment, including gas stoves, produce nitrogen dioxide (NO2), and higher NO2 concentrations, are associated with worse respiratory morbidity in people with obstructive lung disease. A handful of studies have modified the indoor environment by replacing unvented gas heaters; this study, to our knowledge, is the first randomized study to target unvented gas stoves. The results of this study show that simple home interventions, including replacement of an unvented gas stove with an electric stove or placement of HEPA air purifiers with carbon filters, can significantly decrease indoor NO2 concentrations.
authors: Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, MD, USA.
authors: L M
authors: LM
authors: Paulin
authors: G B
authors: GB
authors: Diette
authors: M
authors: M
authors: Scott
authors: M C
authors: MC
authors: McCormack
authors: E C
authors: EC
authors: Matsui
authors: J
authors: J
authors: Curtin-Brosnan
authors: D L
authors: DL
authors: Williams
authors: A
authors: A
authors: Kidd-Taylor
authors: M
authors: M
authors: Shea
authors: P N
authors: PN
authors: Breysse
authors: N N
authors: NN
authors: Hansel
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D016902:Air Pollution, Indoor / Q000032:analysis / Q000517:prevention & control*; D015142:Baltimore; D003296:Cooking / Q000379:methods*; D004784:Environmental Monitoring / Q000379:methods*; D006798:Housing; D006801:Humans; D009585:Nitrogen Dioxide / Q000032:analysis*; D018709:Statistics, Nonparametric
chemical_list: D000393:Air Pollutants; D009585:Nitrogen Dioxide
keywords: Air purifier; Gas stove; Housing intervention; Indoor air; Nitrogen dioxide; Urban environment