Indoor Air Pollution and Children With Asthma: An Intervention Trial
Condition: Asthma
MeSH terms: Asthma
Study type: Interventional

Summary: 
      The purpose of this study is to determine whether reducing indoor exposure to NO2 and
      particles improves respiratory health in children with asthma.
    

Detailed description: 
      We have designed a randomized, double-blind, triple cross-over intervention study to examine
      the efficacy of indoor NO2 reduction on reducing asthma severity. Since particles and NO2 are
      both byproducts of combustion and associated with gas stove use, the intervention protocol
      includes a condition using a filter designed to remove particles also implicated in asthma
      exacerbations (e.g., coarse, fine and ultrafine particles including airborne mold spores and
      allergens) while leaving NO2 virtually untouched. Primary and secondary aims of the trial
      include, respectively, determining whether reducing exposure to NO2 and particles compared to
      a "control" (non-filtered) condition results in a clinically significant reduction in asthma
      severity measured by a difference in days of symptoms between intervention arms.

      Families with asthmatic children age 5-11 will be recruited from selected communities using
      a: (1) flyers distributed in elementary schools, (2) postcards send to families from
      purchased mailing lists, (3) posters placed in community buildings (libraries, clinics,
      etc.), (4) online (Facebook, Craigslist), and (5) letter mailed to families targeted through
      Yale Joint Data Analytics Team (JDAT). Volunteers will be screened for preliminary
      eligibility based on household characteristics and active asthmatic status. Potentially
      eligible families will have homes with a gas cooking stove and seven rooms or fewer.
      Potentially eligible children will be aged 5-11; have asthma symptoms and/or medication use
      consistent with severity score categories 2 (mild persistent), 3 (moderate), or 4 (severe)
      during the previous 12 months; and reside at least 5 days and nights every week in the
      eligible home.

      Households meeting these preliminary criteria will be asked to participate in passive NO2
      sampling. A single Palmes tube will be sent to the home for placement in the main living
      space for one week. Families will be called after one week and instructed to cap and return
      the NO2 monitor in a pre-paid mailer. Families of children living in homes where the one-week
      integrated average NO2 concentration is ≥ 15 ppb will be invited to participate. We will
      permit enrollment of more than one eligible child per family. Participating families will be
      randomized into one of 6 treatment sequences each requiring 3 periods of 4-weeks preceded by
      a 1-week washout period. Randomization will be blocked so that for every 18 subjects
      randomized there will be 3 in each sequence. Randomization will be conducted blindly by the
      data management department such that each scheduled initial interview/air cleaner
      installation is assigned a treatment sequence (referring to machines and filters already on
      site). Minimization techniques will be used to balance the randomized allocation as
      necessary. Total subject participation time up to 18 weeks.
    

Intervention name(s): NO2 Scrubber; HEPA filter; Control
Intervention type(s): Other; Other; Other
Intervention description(s): an NO2 scrubber that removes NO2 and particles; a HEPA filter that removes 95% of suspended particles ≥ 0.003 μm in size (but does not remove NO2); a "control" filter designed to be the same size and weight as the other two filters, but filters neither NO2 nor particles
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Treatment
Keywords: Nitrogen Dioxide; Parts per billion