Indoor Woodsmoke PM and Asthma
Condition: Asthma
MeSH terms: Asthma
Study type: Interventional
Phase: Phase 3

Summary: 
      Although particulate matter (PM) exposures have been linked with poor respiratory health
      outcomes, most of these studies have focused on airsheds with urban and industrial sources of
      PM2.5. Woodsmoke-derived PM also contributes to ambient PM in these urban areas, and is the
      major source of PM in many US rural or peri-urban areas, as well as in many communities
      within developing countries. This study will focus on indoor air quality and clinically
      relevant changes in health effects among asthmatics living in homes whose primary heating
      sources are non EPA-certified woodstoves. The Primary Aim of this study is to assess the
      efficacy of residential interventions to reduce indoor PM exposure from woodstoves and the
      corresponding improvements in quality of life and health outcomes for asthmatic children. The
      study area for this project will be three rural communities in western Montana and Idaho,
      including one Indian Reservation. This study will use a three arm (Tx1, Tx2, and Tx3)
      randomized placebo-controlled intervention trial. The interventions will be at the household
      level, and exposure and outcomes will be assessed for one asthmatic child in each household.
      Households in Tx1 will receive inactive high efficiency particulate air (HEPA) devices and
      will serve as the placebo group. Households in Tx2 will receive a new EPA-certified
      woodstove, while households in Tx3 will receive active HEPA devices. The Secondary Aims of
      this study are to assess the impact of these interventions on residential PM2.5 exposures and
      other health outcomes. Secondary exposure outcomes measured prior to and following the
      intervention will include PM2.5 mass, chemical woodsmoke markers on PM2.5 filters (including
      levoglucosan and abietic acids), and biomarkers of woodsmoke exposure. Secondary
      asthma-related health outcomes measured prior to and following the intervention will include
      peak expiratory flow (PEF) and forced expiratory volume in first second (FEV1), biomarkers in
      exhaled breath condensate, and frequency of asthma symptoms, medication usage, and healthcare
      utilization. To our knowledge, this will be the first randomized trial in the US to utilize a
      woodsmoke intervention to assess the impact of the consequent reductions in indoor PM on
      health outcomes in a susceptible population. The results from this project will be
      translatable to other regions in the US and the world where biomass burning is commonly used
      for heating and cooking.
    

Detailed description: 
      SPECIFIC AIMS Although particulate matter (PM) exposures have been linked with poor
      respiratory health outcomes, most of these studies have focused on populated airsheds with
      urban and industrial sources of PM2.5. In less-urban areas, residential woodstoves are not
      only major sources of ambient PM2.5, but can result in significant woodsmoke exposures in the
      indoor environment. This study will focus on indoor air quality and associated health effects
      among asthmatic children living in homes whose primary heating sources are non EPA-certified
      woodstoves. The primary aim of this study is to assess the efficacy of residential
      interventions to reduce indoor PM exposure from woodstoves and the corresponding improvements
      in quality of life and health outcomes for asthmatic children. This study will allow us to
      characterize the woodsmoke effects on asthmatic conditions and evaluate clinically meaningful
      health outcomes among asthmatics. This will be the first randomized controlled trial in the
      US to utilize a woodsmoke-targeted intervention and assess the impact of the consequent
      reductions in indoor PM on health outcomes in a susceptible population. The results from this
      project will be translatable to other regions in the US and the world where biomass burning
      is commonly used for heating or cooking.

      This study will use a three arm (Tx1, Tx2, and Tx3) randomized placebo-controlled
      intervention trial. The interventions will be at the household level, and exposure and
      outcomes will be assessed for one asthmatic child in each household. Households in Tx1 will
      receive inactive high efficiency particulate air (HEPA) devices and will serve as the placebo
      group. One intervention that will be tested in this trial will be the replacement of old
      woodstoves with cleaner burning EPA-certified woodstoves (Tx2). The other intervention that
      will be tested will be the installation of HEPA filtration devices within the home (Tx3). Our
      preliminary data have demonstrated significant reductions in indoor PM using these
      interventions.

      The Primary Aim of this study is to assess the impact on quality of life among asthmatic
      children following interventions that reduce in-home woodsmoke PM exposures. We will address
      the following primary hypotheses:

      1a. Asthmatic children in homes receiving new woodstoves in Tx2 will have improved
      asthma-specific quality of life measures compared to asthmatic children in placebo
      households, Tx1.

        1. b. Asthmatic children in homes receiving HEPA filtration units in Tx3 will have improved
           asthma-specific quality of life measures compared to asthmatic children in placebo
           households, Tx1.

           The Secondary Aims of this study are to assess the impact of these interventions on
           residential PM2.5 exposures and other health outcomes. We will address the following
           secondary hypotheses:

        2. a. Changes in winter period PM2.5 exposure in homes receiving interventions (Tx2 and
           Tx3) will be greater than changes in winter period PM2.5 exposure in placebo households
           (Tx1). Each treatment group will be evaluated independently against the placebo group.
           Secondary residential exposure outcomes measured repeatedly during pre- and
           post-intervention winter periods will include:

             1. PM2.5 mass

             2. chemical woodsmoke markers on PM2.5 filters (i.e., levoglucosan and abietic acids)

             3. biomarkers of woodsmoke exposure in urine and exhaled breath condensate (i.e.,
                levoglucosan and abietic acids)

      2b. Changes in winter period health outcomes among asthmatic children living in homes
      receiving interventions (Tx2 and Tx3) will be more improved than changes in winter period
      health outcomes in placebo households (Tx1). Each treatment group will be evaluated
      independently against the placebo group. Secondary exposure outcomes will include:

        1. peak expiratory flow (PEF) and forced expiratory volume in first second (FEV1)

        2. biomarkers in exhaled breath condensate (i.e., pH and nitric oxide)

        3. frequency of asthma symptoms

        4. frequency of rescue medication usage

        5. healthcare utilization
    

Intervention name(s): woodstove; inactive air filter; Active air filter
Intervention type(s): Other; Other; Other
Intervention description(s): installation of new EPA-certified woodstove; air filter units without filter in place; air filter units correctly operating
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Basic Science