Published: Jan. 15, 2019

Sarah Hong collecting data

Sarah Hong collects data

Professor Shelly Miller, along with her multidisciplinary team, is studying the impacts of climate change on indoor air quality in low-income Denver-area neighborhoods. Since poor air quality negatively affects human health and is often worse in low-income neighborhoods, Miller and her team aim to uncover ways to reduce and limit indoor pollutants in these areas. To conduct this research, Shelly received a $1 million grant from the Environmental Protection Agency (EPA).  Her most recent study explores the effects of ventilation rates in low-income areas. 

Research Highlights

  1. Air exchange rates (AERS) are a measure of how well ventilated is a building and is a measure of the amount of indoor air that is exchanged with outdoor air.

  2. Air exchange rates were relatively high in many low-income urban homes we tested.

  3. People in homes with higher AERs were more likely to report respiratory symptoms.

  4. This association was generally stronger in areas with more traffic.

  5. High air exchange rates in areas with high traffic-related air pollution areas may lead to respiratory morbidity.


Relationships between home ventilation rates and respiratory health in the Colorado Home Energy Efficiency and Respiratory Health (CHEER) study


As societies adopt green building practices to reduce energy expenditures and emissions that contribute to climate change, it is important to consider how such building design changes influence health. These practices typically focus on reducing air exchange rates between the building interior and the outdoor environment to minimize energy loss, the health effects of which are not well characterized. This study aims to evaluate the relationship between air exchange rates and respiratory health in a multi-ethnic population living in low-income, urban homes.


Prateek Shrestha with blower doorThe Colorado Home Energy Efficiency and Respiratory Health (CHEER) study is a cross-sectional study that enrolled 302 people in 216 non-smoking, low-income single-family homes, duplexes and town-homes from Colorado's Northern Front Range. A blower door test was conducted and the annual average air exchange rate (AAER) was estimated for each home. Respiratory health was assessed using a structured questionnaire based on standard instruments. We estimated the association between AAER and respiratory symptoms, adjusting for relevant confounders.


Air exchange rates in many homes were high compared to prior studies (median 0.54 air changes per hour, range 0.10, 2.17). Residents in homes with higher AAER were more likely to report chronic cough, asthma and asthma-like symptoms, including taking medication for wheeze, wheeze that limited activities and dry cough at night. Allergic symptoms were not associated with AAER in any models. The association between AAER and asthma-like symptoms was stronger for households located in areas with high potential exposure to traffic-related pollutants, but this was not consistent across all health outcomes.


While prior studies have highlighted the potential hazards of low ventilation rates in residences, this study suggests high ventilation rates in single-family homes, duplexes and town-homes in urban areas may also have negative impacts on respiratory health, possibly due to the infiltration of outdoor pollutants.

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