We’ve just wrapped a multi-year effort to build, test and validate a new way of taking indoor air measurements. The culmination is a comprehensive indoor air sampling instrument we call the Home Health Box. I wrote this blog post as a short primer on indoor air pollutants for the uninitiated, like me, that don’t have a professional background in air sampling and may not understand how these pollutants end up in (or are generated in) the home.
Indoor air quality (IAQ) encompasses the composition of air within enclosed spaces, influencing occupant health, cognitive function, and productivity. Scientific research underscores its role in respiratory diseases, cardiovascular issues, and neurobehavioral effects, with exposure to pollutants contributing to millions of annual deaths globally. For researchers and professionals, understanding IAQ involves quantifying pollutant concentrations, assessing exposure risks, and evaluating mitigation strategies. This post frames IAQ through "nouns" (pollutants) and "verbs" (generating activities), focusing on residential and commercial settings.
In residences, where individuals spend ~90% of their time, IAQ is compromised by building materials, polluting appliances, and everyday activities. Key "nouns" include particulate matter (PM2.5 and PM10), volatile organic compounds (VOCs), nitrogen dioxide (NO2), carbon monoxide (CO), radon, ozone (O3), heavy metals, aerosols, pesticides, and biological contaminants like mold and allergens.
PM, comprising sulfates, nitrates, and metals, arises from cooking, smoking, and cleaning, which is correlated with cardiovascular and respiratory morbidity. VOCs, with indoor levels often higher than outdoor, off-gas from painting, furnishing, and using solvents/adhesives, causing irritation, organ damage, and cancer risks. NO2 and CO stem from gas appliance combustion during heating or cooking, exacerbating asthma and inducing fatigue/chest pain. [Fun note: you can see one of the early Home Health Box designs in this PBS clip on gas stoves and indoor air quality] Radon infiltrates passively from soil, elevating lung cancer risk. Mold and allergens proliferate in damp environments from water leaks or showering, triggering allergies and infections. Outdoor pesticide spraying can migrate indoors, posing neurotoxic and carcinogenic threats.
Office spaces, with high occupancy, amplify IAQ challenges through shared systems and equipment. Common nouns include VOCs, PM, O3, CO2, and microbial agents.
VOCs and formaldehyde are emitted during renovations, from furniture, or cleaning with chemicals. Printers and photocopiers generate O3 and toner particles during operation, irritating respiratory tracts and impairing lung function. PM and aerosols arise from dusting or outdoor infiltration via HVAC. CO2 elevates from breathing in meetings, correlating with cognitive deficits at >1000 ppm. Mold grows in moist HVAC from poor maintenance, causing sick building syndrome (SBS) symptoms like headaches and fatigue. ASHRAE standards recommend <700 ppm CO2 and specific ventilation rates to mitigate.
For scientific inquiry, the tools used to understand indoor air quality have needed an upgrade for quite some time. That's why we developed the Home Health Box. We wanted to open up the way people sample and measure indoor air. Our tools offer some key features:
We often worry about the nouns but with the right tools you can identify the verbs and that’s what may make the difference in improving IAQ.
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