In this episode of the NAFA Podcast, recorded live at NAFA’s 2025 Technical Seminar, Dr. Joseph Allen, Director of the Healthy Buildings Program at Harvard T.H. Chan School of Public Health, delivers a compelling keynote on why healthy buildings are central to public health, productivity, and safety.

Dr. Allen explores how cleaner air improves cognitive function, why outdated ventilation standards fail to protect people, and how the COVID-19 pandemic reshaped the science and policy of indoor air. He shares actionable strategies for building owners, engineers, employers, and policymakers to improve indoor environments through better ventilation, filtration, and design standards.

Listeners will learn about the history of ventilation standards, the breakthrough shift in recognizing airborne transmission of COVID-19, the movement toward health-based ventilation targets, and the rise of low-cost indoor air monitoring tools that are transforming accountability in buildings worldwide.

Whether you work in air filtration, facilities management, public health, or are simply curious about the air you breathe, this episode offers practical takeaways and a vision for the future of healthy buildings.

00:00 – 00:31 Introduction to the NAFA Podcast and its mission.

00:31 – 01:05 Overview of the episode: Dr. Joseph Allen on the science and business case for cleaner indoor air.

01:05 – 01:28 Practical steps for professionals, employers, and policymakers to improve indoor environments.

01:28 – 02:02 Acknowledgments to NAFA and opening remarks.

02:02 – 03:02 Audience quiz on indoor air and how much time people spend indoors (90%).

03:02 – 04:13 Why buildings are missing from decades of public health studies and why this gap matters.

04:13 – 05:34 Quiz continues: ventilation standards, particle exposure, and how much air comes from others in the room.

05:34 – 06:09 Introduction to strategies for reducing respiratory disease indoors.

06:09 – 07:12 Buildings as frontline tools during pandemics and early COVID-19 insights.

07:12 – 09:14 Making the case for airborne transmission during the pandemic and why recognition was delayed.

09:14 – 10:24 Modeling airborne transmission and demonstrating how ventilation and filtration reduce spread.

10:24 – 11:09 Breaking into top medical journals and shifting decades of assumptions about transmission.

11:09 – 12:28 The “first four healthy building strategies”: commissioning, ventilation, filtration, and portable air cleaners.

12:28 – 13:24 Portable air cleaners: effectiveness, placement, and the importance of mixing.

13:24 – 14:38 Why airflow and mixing are critical to reducing infection risks.

14:38 – 15:29 The challenge of setting health-based ventilation targets—moving beyond “acceptable” standards.

15:29 – 16:51 Historical perspective: ventilation targets in the 1800s and how they regressed in the 1970s.

16:51 – 18:10 COVID-19 guidance: 4–6 air changes per hour and the need for clear targets.

18:10 – 19:56 Consensus building: Lancet Commission and the push toward 30 CFM/person or 5 ACH.

19:56 – 21:14 Adoption of new standards by ASHRAE, CDC, and state health departments.

21:14 – 22:22 A major turning point: reframing ventilation as a cornerstone of public health.

22:23 – 23:14 NAFA certifications and professionalism in air filtration.

23:14 – 24:18 Public awareness shift: indoor air quality on the front page of The New York Times and 60 Minutes.

24:18 – 26:01 Technology shift: rise of low-cost air quality monitors and their impact on accountability.

26:01 – 27:34 The public’s new ability to “interview” buildings and the power shift in knowledge.

(Episode continues with additional research insights and closing commentary.)

Episode Timestamps