Table 1.

Summary of authoritative or comprehensive evaluations and other relevant data on formaldehyde exposure concentrations associated with or protective from symptoms of sensory irritation or other adverse effects.

Formaldehyde air concentration (ppm)	Source	Comment/observation
6-15	Monticello et al. 1996; Kerns et al. 1983a, b;	Chronic inhalation dose range required for the sustained cytotoxicity and regenerative proliferation leading to development of nasal tumors.
1.0	TNO, 2003; Arts et al., 2006	“..… minimal/mild/slight eye irritation starts at levels of 1.0 ppm formaldehyde and higher.”
0.9	EPA, 2004; Acute exposure guideline level (AEGL)	“At 0.35 to 0.9 ppm, the subject's subjective eye irritation responses ranged from none to slight, the same as their responses to clean air.”
0.75	OSHA, 2006; (Occupational exposure standard) Noisel et al. 2007	In effect for many years with no evidence of significant worker complaints of sensory irritation. “The level of 0.75 ppm can be considered as a safe level that allows protecting virtually all workers.”Noisel et al. (2007)
	Noisel et al., 2007	“The level of 0.75 ppm can be considered as a safe level that allows protecting virtually all workers.”
0.7	Andersen et al., 2008, 2010	Inhaled concentration in rats that produces no significant toxicogenomic changes in nasal epithelial cells following 21 or 90 days of exposure.
0.5	Lang et al., 2008 (most recent controlled human study) EPA/NCEA 2005	““… the no-observed-effect level for subjective and objective eye irritation due to formaldehyde exposure was 0.5 ppm in case of constant exposure level and 0.3 ppm with peaks of 0.6 ppm in terms of short term peak exposures.” Clear threshold at 0.5 ppm for any effects (including odor) with an effective concentration at 1.5 ppm for moderate effects.
	US EPA/NCEA, 2005	Clear threshold at 0.5 ppm for any effects (including odor) with an effective concentration at 1.5 ppm for moderate effects.
0.3	ATSDR, 1999, 2007,NAS, 2007,WHO, 2010 ACGIH, 2001 MAK, 2006,OECD/SIDS, 2002 NICNAS, 2005	Most weight of evidence–based reviews conclude that 0.3 ppm is a reasonable and appropriate level below which symptoms of sensory irritation are unlikely to occur, e.g., “…symptoms of eye and mucous membrane irritation at that concentration were not increased above control conditions in controlled chamber studies.” (NAS, 2007) and “Studies in the literature have reported a variety of responses induced by exposure to gaseous formaldehyde, generally beginning in the range of 0.3 to 0.5 ppm for eye irritation, the most sensitive endpoint. However, the severity of response at these levels is generally mild, and only a small portion of the population may respond.” (OECD/SIDS, 2002).
0.2	SCOEL, 2008	“This especially considers possible interindividual differences in susceptibility to irritation by formaldehyde, which may be expected based on the entire body of data.”
0.1	BfR, 2006; Health Canada, 2001, 2005; ASHRAE NASA/NAS, 2008	Partially derived from animal data, i.e., “The proposed level of 0.1 ppm is 2 fold lower than the level derived from animal data by applying appropriate safety factors.” [emphasis in original]. 0.1 ppm (1 hour) = 1/5th of NOAEL (i.e., 0.5 ppm) for eye irritation.
0.08	WHO, (2010); Wolkoff and Nielsen, 2010	“An air quality guideline of 0.1mg/m3 (0.08 ppm) is considered protective against both acute and chronic sensory irritation in the airways in the general population assuming a log normal distribution of nasal sensory irritation.” “Thus, prevention of nasal cancer is considered to prevent lymphohematopoietic malignancies…. the guideline value of the WHO [of]… 0.08 ppm FA, is considered preventive of carcinogenic effects in compliance with epidemiological findings.”
	WHO, 2010; Nielsen and Wolkoff, 2010	“Thus, prevention of nasal cancer is considered to prevent lymphohematopoietic malignancies…the guideline value of the WHO [of]…0.08 ppm FA, is considered preventive of carcinogenic effects in compliance with epidemiological findings.”