The smell does 'not' have to be prevalent for it to be dangerous to your health. The very small square footage in an RV just escalates the level of concentration.
"...the U.S. Environmental Protection Agency (EPA) classified formaldehyde as a probable human carcinogen under conditions of unusually high or prolonged exposure (1). Since that time, some studies of humans have suggested that formaldehyde exposure is associated with certain types of cancer. The International Agency for Research on Cancer (IARC) classifies formaldehyde as a human carcinogen (2). In 2011, the National Toxicology Program, an interagency program of the Department of Health and Human Services, named formaldehyde as a known human carcinogen ..."
Here is the CDC report. AND remember the CDC takes the low road when reporting toxicity especially when if the product is used in manufacturing so you can X10 the effect formaldehyde has on the human body.
http://www.atsdr.cdc.gov/mmg/mmg.asp?id=216&tid=39
