Air quality is a volatile concept. Levels of volatile organic compounds (VOCs) change constantly, and so do the regulations that control them. The Environmental Protection Agency (EPA) list of VOCs is a comprehensive starting point for identifying and reducing hazardous substances.
Note that using a smart indoor air quality monitor is recommended by local and international regulatory bodies for the indoor air quality (IAQ) of private and public buildings.
EPA IAQ standards and guidelines
Air quality is essential to people's well-being as well as to the environment. Poor air quality, indoors and outdoors, can lead to many health problems, such as nausea, headaches, skin irritation, sick building syndrome (SBS), kidney failure and even cancer. Indeed, since people spend about 90% of their time indoors, indoor air quality has a significant impact on people's health.
It is therefore no surprise that establishing strict standards and guidelines is fundamental to people's environmental health. Note that for some pollutants, there are no safe exposure levels. Although limit values vary between countries and organizations, the EPA describes several common VOCs and substances along with their limit values in the United States:
- PM2.5: Fine particulate matter is one of the most dangerous forms of pollution because the particles are so small that they can penetrate the lungs and cause many adverse effects. PM2.5, in particular, are particles 2.5 μm or less in diameter. Their limit value is 25 μg/m3, based on 24-hour data.
- CO: An odorless, colorless and deadly gas, carbon monoxide (CO) is one of the most dangerous compounds in indoor environments. The American Conference of Governmental Industrial Hygienists (ACGIH) has set a limit value of 25 ppm for an 8-hour workday, while the National Institute for Occupational Safety and Health (NIOSH) recommends an exposure limit of 35 ppm.
- CO2: CO2 is a naturally occurring compound in the air, with an average outdoor concentration of 300-400 ppm. Note that indoor levels are higher because indoor spaces are enclosed. Effects on human health can be observed at levels above 7,000 ppm. Accordingly, the occupational limits set by the ACGIH are 5,000 ppm TLV-TWA* and 30,000 ppm TLV-STEL**.
- Radon: Radon is a radioactive gas formed by the decay of (naturally occurring) uranium in the soil. Since radon is carcinogenic, there are no safe exposure levels. Still, the EPA has set an action level of 4 pCi/L.
- PAHs: Polycyclic aromatic hydrocarbons (PAHs) are semi-volatile organic compounds that are hazardous to people's environmental health. Each PAH has different limit values. Naphthalene, in particular, is the most volatile PAH. Its recommended limit value is 10 ppm.
- Formaldehyde: One of the most common VOCs, formaldehyde can be emitted by many sources, such as furniture, incense burning and cooking. Note that its limit value is 0.1 ppm TLV-TWA* and 0.3 ppm TLV-STEL**.
- Dichloromethane: Dichloromethane, or methylene chloride, can be found in products such as solvents. Its odor threshold is 250 ppm. Note that prolonged exposure can lead to central nervous system problems.
- NO2: Because of the adverse effects associated with nitrogen dioxide (NO2), the EPA has strengthened its health guidelines and set a 1-hour standard at the level of 100 ppb.
*TLV-TWA: Threshold Limit Value - Time-Weighted Average (usually 8 hours). **TLV-STEL: Threshold Limit Value - Short-Term Exposure Limit (usually 15 minutes).
Understanding and improving indoor air quality
From cigarette smoke to exhaust fumes, sources of VOCs, PM2.5 and NO2 are all around us. Understanding where hazardous gases and particles come from is essential to helping people lower pollutant concentrations and reduce the health problems linked to poor air quality. There are a few fundamental steps that can help individuals improve indoor air quality.
- Buy low-VOC products
- Consider plants that can purify the air
- Focus on good ventilation systems with HEPA filters
When it comes to office buildings, HVAC systems can improve indoor air quality, leading to better health outcomes. Note that the standards of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) are carefully developed to help professionals assess and improve ventilation in private and commercial buildings. In addition, the Occupational Safety and Health Administration (OSHA) has strict standards regarding ventilation, particularly in educational and medical facilities.
IAQ issues and outlook
Having strict standards for IAQ and ventilation can improve air quality. Nevertheless, measuring VOC concentrations in private homes can be challenging. Many factors, such as location, humidity level and air velocity, can affect emission levels. As a result, different regulatory bodies have different limit values and guidelines. Note that in addition to the values listed above, the World Health Organization (WHO) also provides clear guidelines for indoor air quality and proper ventilation.
- Updating the limit values for VOCs and pollutants is the first step toward better industrial hygiene.
- Understanding how VOCs affect the environment as well as occupational health is essential.
- Testing for VOCs regularly is advisable to improve environmental and health outcomes.
Sources
- https://www.epa.vic.gov.au/your-environment/air/air-pollution/pm25-particles-in-air/what-are-one-hour-and-24-hour-averages
- https://www.epa.gov/indoor-air-quality-iaq/carbon-monoxides-impact-indoor-air-quality
- http://www.ncceh.ca/documents/practice-scenario/carbon-dioxide-indoor-air
- https://www.radon.com/radon_levels/
- https://www.cdc.gov/niosh/idlh/91203.html
- https://www.ncbi.nlm.nih.gov/books/NBK217660/
- https://www.epa.gov/sites/production/files/2016-09/documents/methylene-chloride.pdf
- https://www3.epa.gov/airnow/no2.pdf
- https://www.safeopedia.com/definition/610/short-term-exposure-limit-stel