I recently reviewed a report from an indoor air quality (IAQ) test conducted in a private residence. What stood out immediately was that the results for volatile organic compounds (VOCs), carbon monoxide (CO), and carbon dioxide (CO₂) were compared to Occupational Exposure Limits (OELs)—standards designed for workplace environments, not homes.
This is a critical misstep, and it highlights the need for using the correct air quality standards for residential environments.
Why You Shouldn’t Use Occupational Exposure Limits for Homes
One of the core principles of toxicology is “The dose makes the poison,” a phrase credited to Paracelsus in the 1500s. In other words, the health effects of any substance—whether it’s a chemical contaminant, VOC, or carbon monoxide—depend on how much enters the body over time.
Historically, small amounts of arsenic were used to improve skin appearance or animal health temporarily. But even small exposures, when repeated or misused, can be fatal—as demonstrated by the mysterious deaths of horses given arsenic to boost their appearance before being sold.
This idea of dose is at the heart of why we use different exposure limits for indoor air in homes versus workplaces. Dose depends on:
- The concentration of the contaminant,
- Duration of exposure, and
- Frequency of exposure.
Because these factors are vastly different at home, it’s dangerous and misleading to use workplace exposure limits for residential air quality assessment.
How Occupational Exposure Limits Are Determined
Occupational Exposure Limits were created with workplace safety in mind, not home use. Key assumptions include:
- Target population: healthy working adults—originally young military recruits, now often graduate student volunteers.
- Exposure time: typically 8 hours a day, 5 days a week, with recovery time away from the exposure source.
- Environmental control: relatively stable, repetitive tasks with known chemical sources.
Additional limitations of OELs include:
- Most are not designed for extended exposure periods, like 10- or 12-hour shifts.
- They do not account for combined environmental exposures, such as vehicle exhaust, secondhand smoke, or pesticides.
- They assume exposure patterns are predictable and easily measured.
Where to find Occupational Exposure Limits:
- Occupational Safety and Health Administration Tables Z-1, Z-2, and Z-3, as well as the expanded standards, provide enforceable exposure limits.
- National Institute of Occupational Safety and Health (NIOSH) provides Recommended Exposure Limits.
- The American Conference of Governmental Industrial Hygienists (ACGIH) is a national professional association that researches, creates, and updates exposure limits, most of which are called Threshold Limit Values. However, you have to pay for them.
Why Homes Need Different Indoor Air Quality Standards
Residential settings involve completely different exposure scenarios. Here’s why residential indoor air quality limits must be more conservative:
- Vulnerable populations: Children, elderly adults, people with preexisting health conditions, and pets are more susceptible to indoor air pollutants.
- Extended exposure: Many residents spend 12–24 hours per day at home, especially young children, retirees, and people working remotely.
- Variable proximity to pollutants: Unlike controlled workplaces, people in homes move between rooms and may unknowingly spend long periods near an emission source.
- Undetectable hazards: Many dangerous gases like radon and carbon monoxide are odorless and colorless.
- Individual sensitivity: One family member may suffer from chemical sensitivity while others remain unaffected.
These differences make it essential to rely on residential air quality guidelines, not OELs, when interpreting the results of a home air test.
Where to Find Residential Indoor Air Quality Guidelines
Finding accurate safe indoor air quality levels can be challenging, but there are credible resources available:
- ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) offers guidance on acceptable levels of VOCs, CO, CO₂, and relative humidity in residential and commercial buildings. Their standards are science-based, though sometimes paywalled.
- The EPA (Environmental Protection Agency) provides free information on indoor pollutants, including recommendations for residential carbon monoxide levels and air purification strategies. While EPA data often focuses on outdoor air pollution, it’s still highly relevant for indoor assessments.
Search tip: Use focused terms such as:
- “Safe VOC levels in homes”
- “Carbon monoxide exposure limits for residential settings”
- “ASHRAE indoor air quality standards for homes”
Final Thoughts: Use the Right Standard for the Right Setting
Indoor air pollution is a growing concern, especially in tightly sealed, energy-efficient homes. While Occupational Exposure Limits are essential tools for workplace health and safety, they are not suitable for evaluating home environments.
When assessing your home’s air quality:
- Look for residential-specific air quality benchmarks,
- Consult reputable sources like ASHRAE and the EPA,
- And remember that air contaminants affect people differently based on age, health status, and lifestyle.
For meaningful insight and peace of mind, always make sure you’re using the right standard for the right environment.
Need Accurate Air or Noise Sampling? Call a Certified Expert.
Don’t rely on guesswork or inappropriate exposure limits when it comes to your health or compliance needs. A Certified Industrial Hygienist (CIH) brings extensive training, real-world experience, and scientific expertise—especially in air and noise sampling.
When you’re evaluating a workplace environment, a CIH ensures you’re using the right methods and standards to protect employees and meet regulatory requirements.
📞 Call 920-944-9143 or
📧 Email cih@psahs.com to connect with a CIH who has over 25 years of experience in occupational exposure monitoring and environmental health assessments.