COLUMBIA, Md. (April 13, 2022) – A mechanical system to ventilate homes could save thousands of lives and prevent major health consequences, according to a new study released today by Enterprise Community Partners (Enterprise) and the National Center for Healthy Housing (NCHH), and funded by The JPB Foundation.

In Studying the Optimal Ventilation for Environmental Indoor Air Quality, researchers found that mechanical ventilation systems significantly reduced dangerous particulate matter, carbon dioxide, carbon monoxide, and formaldehyde from indoor air, reducing the risk of respiratory and cardiovascular illness. Although such systems are recommended in industry-leading standards from the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), over 90 percent of rental homes in America do not have them.

Still, even in homes with such ventilation systems, researchers did not observe significant changes in the levels of nitrogen dioxide, which primarily come from gas stoves, countering the misconception that opening windows or increasing ventilation is enough to address the health impacts of these appliances.

Based on these findings, the study recommends that builders and owners install continuous mechanical ventilation systems in all homes, while eventually phasing out gas stoves altogether. 

Thus far, most homes have not followed the ASHRAE standards because they can be costly and complex to implement. Given the significance of the findings, the authors urge ASHRAE to simplify the standards and state and federal authorities to provide financing tools that make these changes easier to implement nationwide. The issue is particularly urgent for people living in low-income communities, who are disproportionately impacted by the harms poor air quality can cause.

“Thousands of Americans are dying every year from preventable illnesses exacerbated by poor air quality, and this study shows we have the tools at our disposal to fix this systemic issue. Installing mechanical ventilation and transitioning from gas stoves to electric would have a significant impact on public health, particularly in lower-income communities,” said Stephany De Scisciolo, vice president of impact and evaluation at Enterprise and a collaborator on the study. “We’re grateful to our partners at the National Center for Healthy Housing (NCHH) and The JPB Foundation for making this incredibly important study possible.”

The 20 percent reduction in particulate matter, known as PM2.5, was especially noteworthy because of the significant public health impacts. This latest study shows that if all multifamily housing in the United States were able to install continuous mechanical ventilation systems, the resulting decrease in indoor PM2.5 alone would likely lead to:

  • 14,800 fewer deaths
  • 11,800 fewer emergency department visits due to asthma
  • 8,100 fewer hospitalizations due to respiratory or cardiovascular illness

The findings are based on data collected in 2018-2021 by local partners Icahn School of Medicine at Mount Sinai in New York City and the School of Public Health at the University of Illinois Chicago. The study included two groups of multifamily affordable homes rehabilitated using green practices—one that complied with the industry-leading ASHRAE standard, and one that did not. The researchers measured the following impacts of continuous mechanical ventilation on indoor air quality compared to the control group: 

Contaminant Health Impact Measured Difference
with Continuous ASHRAE-Compliant Mechanical Ventilation
Particulate matter (PM2.5) Exacerbates respiratory and cardiovascular health issues; increases premature mortality  20% improvement
Carbon dioxide Reduces cognition and reasoning 13% improvement
Carbon monoxide Increases risk of cardiovascular impairment 25% improvement (with continuous kitchen exhaust)
Formaldehyde Increases risk of cancer 44% improvement (with continuous kitchen exhaust)
Nitrogen dioxide Reduces respiratory and cardiovascular health No significant change observed

Based on the results of the study, the authors outlined a series of recommendations to improve indoor air quality in housing across the country:

  • All property owners should install and maintain continuous mechanical ventilation systems.
  • All property owners should replace gas stoves with electric.
  • All green building standards and local building codes should conform to ASHRAE Standard 62.2, the industry standard for indoor air quality.&
  • Technical assistance should be provided to building owners, property managers, developers, and financing institutions to expand adoption of ASHRAE Standard 62.2.
  • Housing rehabilitation financing programs should include the cost of installing mechanical ventilation as a portion of housing improvement budgets.

“Ventilation is much more important than we previously thought,” said David Jacobs, chief scientist at NCHH. “This study gives us three clear takeaways: All gas stoves should be replaced, all apartments should have continuous mechanical ventilation, and outdoor air pollution affects indoor air. Ensuring our homes are healthy ones is key to preventing illness and promoting well-being.”

The results from the study affirm the importance of ASHRAE-compliant mechanical ventilation as an element of Enterprise’s Green Communities program, a national standard for green affordable housing.  Today, 30 states require or encourage developers seeking affordable housing funding to follow the Green Communities Criteria.
About Enterprise Community Partners
Enterprise is a national nonprofit that exists to make a good home possible for the millions of families without one. We support community development organizations on the ground, aggregate and invest capital for impact, advance housing policy at every level of government, and build and manage communities ourselves. Since 1982, we have invested $54 billion and created 873,000 homes across all 50 states, the District of Columbia and Puerto Rico – all to make home and community places of pride, power and belonging. Join us at
About the National Center for Healthy Housing
The National Center for Healthy Housing (NCHH) is a leading national nonprofit dedicated to transforming lives by transforming housing. Since 1992, NCHH has served as a highly regarded and credible change agent, successfully integrating healthy housing advocacy, research, and capacity building under one roof to reduce health disparities nationwide. Learn more at

About The JPB Foundation
The JPB Foundation works to advance opportunity and justice in the US by reducing poverty, sustaining and enriching the environment, and furthering breakthrough medical research. The JPB Foundation works alongside local leaders, national movements, and world-changing research organizations to make people’s lives better.

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