Although there are no requirements set for formaldehyde concentration limits in homes, there are a number of recommendations that may be useful. Many organizations or government authorities suggest formaldehyde concentrations not exceed 100-120 ng/L (80-100 parts per billion or ppb) and 50-60 ng/L (40-50 ppb) for short term and longer term exposures, respectively. Some organizations or government authorities recommend more stringent levels for longer term exposures. In general, formaldehyde concentrations should be kept as low as reasonably achievable. Most homes measured by Prism’s air test have concentrations in the range of 30 to 70 ng/L
For an occupational exposure reference, the National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 20 ng/L (16 ppb). The Occupational Safety and Health Administration (OSHA) has set a workplace permissible exposure limit (PEL) of 940 ng/L (750 parts per billion).
Health effects vary depending on the individual. Common symptoms of acute exposure include irritation of the throat, nose, eyes, and skin; this irritation can potentially exacerbate asthma symptoms and other respiratory illnesses. Long term, or chronic, exposure may also cause chronic runny nose, chronic bronchitis, and obstructive lung disease. In 2004, the International Agency for Research on Cancer (IARC) reclassified formaldehyde from “probably carcinogenic to humans” to “carcinogenic to humans” related to nasopharyngeal cancer. Since many factors are involved in the development of cancer, no definitive “safe level” of exposure has been established. The best way to reduce the risk of cancer is to limit exposure.
There are many possible sources for formaldehyde in a home, although building products typically make up a large proportion of the concentration. Any recent renovation or new materials brought into the home is likely to increase the formaldehyde levels. The concentration will decrease over time as the materials off gas, so increasing the ventilation as much as possible is typically the best way to quickly decrease the formaldehyde in your home after recent renovation or installation of new materials.
Formaldehyde is also produced naturally in living systems, e.g., trees and other plant life, and during decay and combustion processes. Formaldehyde is also involved in atmospheric processes. Outdoor concentrations of formaldehyde from both natural and man-made sources can range from less than 1 ng/L in remote areas to 10-20 ng/L in urban environments.