The average adult breathes in and out over 20,000 times a day,Footnote 134 making breathing a major exposure pathway for many hazards.Footnote 135 Poor air quality is the second-biggest factor in early deaths worldwide,Footnote 136 and can impact thinking, learning, attendance, worker retention, vocal health, and more. Heat and wildfire smoke worsen air quality further, making it an increasing issue with climate change.Footnote 137
Indoor levels of some pollutants can be 2–5 times higher than they are outside,Footnote 138 arising from activities (e.g., set construction, costume dyeing, theatrical fog, cleaning or disinfecting products), occupants (e.g., pet dander, infectious illnesses), or the building itself (e.g., off-gassing materials, mould). This makes improving indoor air quality in crowded public settings one of the most cost-effective public health interventions, with a benefit-cost ratio of up to 100:1.Footnote 139 Some performance venues are leading the way on clean air: for example, Vancouver's Orpheum Theatre, built following the 1918 flu pandemic, is known for its excellent ventilation system.Footnote 140
Clean air guides and primers:
- Indoor air quality fact sheets | ASHRAE
- Indoor air quality reports | OSPE
- Guidance for indoor air quality professionals | Health Canada
- COVID-19 indoor air quality checklist for community spaces | Li et al.
Risk calculators:
- OSPE air quality calculator | OSPE
- COVID-19 aerosol transmission estimator | Jimenez & Peng
- Indoor CO2 analysis tool | National Institute of Standards and Technology
- Class/meeting room ventilation calculation tool | Occupational Health Clinics for Ontario Workers (OHCOW)
- ARIA indoor airborne risk assessment tool | WHO
- Airwareness support app | Air Support Project
Footnotes (7)
- “How Your Lungs Work,” Canadian Lung Association, last modified June 3, 2026, https://www.lung.ca/lung-health/lung-info/breathing. Back to text
- Health Effects of Air Pollution – Evidence and Implications: Technical Brief, WHO Air Quality, Energy and Health Science and Policy Summaries (World Health Organization, 2026), 2–5, https://doi.org/10.2471/B09563; Fu Chen et al., “Breathing in Danger: Understanding the Multifaceted Impact of Air Pollution on Health,” Ecotoxicology and Environmental Safety 280 (2024): 116532, https://doi.org/10.1016/j.ecoenv.2024.116532; Samuel Wallbanks et al., “Impact of Environmental Air Pollution on Respiratory Health and Function,” Physiological Reports 12 (2024): e70006, https://doi.org/10.14814/phy2.70006; Great Lakes Health Effects Program et al., The Health and Environment Handbook for Health Professionals: Health and Environment (Health Canada, 1998), 80–81, https://publications.gc.ca/collections/Collection/H46-2-98-211E-8.pdf. Back to text
Joseph G. Allen et al., “Associations of Cognitive Function Scores with Carbon Dioxide, Ventilation, and Volatile Organic Compound Exposures in Office Workers: A Controlled Exposure Study of Green and Conventional Office Environments,” Environmental Health Perspectives 124, no. 6 (2015): 805–12, http://dx.doi.org/10.1289/ehp.1510037; Ontario Society of Professional Engineers, Special Topics in Indoor Air Quality Report: Impacts on Health, Well-Being, and Cognitive Function (Ontario Society of Professional Engineers, 2025), 4–10, https://ospe.on.ca/wp-content/uploads/2025/07/Impacts-on-Health-REPORT.pdf; “Evidence from Scientific Literature about Improved Academic Performance,” United States Environmental Protection Agency, last modified June 23, 2026, https://www.epa.gov/iaq-schools/evidence-scientific-literature-about-improved-academic-performance; Young-Hoon Joo et al., “Association Between Chronic Laryngitis and Particulate Matter Based on the Korea National Health and Nutrition Examination Survey 2008–2012,” PLOS One 10, no. 7 (2015): e0133180, https://doi.org/10.1371/journal.pone.0133180; Liisa Vilén et al., “The Association of Voice Problems with Exposure to Indoor Air Contaminants in Health Care Centres — the Effect of Remediation on Symptom Prevalence: A Follow-Up Study,” Indoor and Built Environment, 33, no. 2 (2024): 314–24, https://doi.org/10.1177/1420326X231197184;
Health Effects Institute, State of Global Air Report 2025 (Health Effects Institute, 2025), 4, https://www.stateofglobalair.org/resources/report/state-global-air-report-2025.
Back to text- Jay Lau, “Extreme Heat Worsens Air Pollution Health Risks,” Harvard T. H. Chan School for Public Health, July 7, 2025, https://hsph.harvard.edu/news/extreme-heat-worsens-air-pollution-health-risks/; Health Canada, Wildfire Smoke and Your Health (Health Canada, 2024), https://www.canada.ca/en/health-canada/services/publications/healthy-living/wildfire-smoke-health.html; Chantelle Burton et al., “Global Burned Area Increasingly Explained by Climate Change,” Nature Climate Change 14 (2024): 1186–92, https://doi.org/10.1038/s41558-024-02140-w. Back to text
Neil E. Klepeis et al., “The National Human Activity Pattern Survey (NHAPS): A Resource for Assessing Exposure to
Environmental Pollutants,” Journal of Exposure Science & Environmental Epidemiology 11, no. 3 (2001), 231–52, https://doi.org/10.1038/sj.jea.7500165; “Indoor Air Quality,” United States Environmental Protection Agency, last modified May 27, 2026, https://www.epa.gov/report-environment/indoor-air-quality.
Back to text- Johns Hopkins Center for Health Security, Model Clean Indoor Air Act (Johns Hopkins Center for Health Security, 2023), 6, https://centerforhealthsecurity.org/sites/default/files/2024-07/240710-mciaa.pdf; Angela Chang et al., “Benefit-Cost Analysis in Disease Control Priorities,” Disease Control Priorities: Improving Health and Reducing Poverty, 3rd ed., eds. Dean T Jamison et al. (2017), https://www.ncbi.nlm.nih.gov/books/NBK525301/. Back to text
- Daniella Barreto, host, Public Health is Dead, podcast, season 1, episode 2, “An Air-Raising Experience at the Orpheum Theatre,” December 22, 2024, https://www.publichealthisdead.com/episodes/orpheumtheatre; “Indoor Air Quality Pioneers,” Let’s Air, accessed July 9, 2026, https://letsair.org/#pioneers. Back to text