Formaldehyde is found in cigarette smoke. It's also used to preserve dead animals.
"Smoking and Tobacco Control." U.S. Department of Health and Human Services, Public Health Service, National Institutes of Health, National Cancer Institute. Risks Associated with Smoking Cigarettes with Low Machine-Measured Yields of Tar and Nicotine, Oct. 2001.http://cancercontrol.cancer.gov/tcrb/monographs/13/m13_complete.pdf
"Controlling Formaldehyde Exposures During Embalming." CDC. 06 June 2014. Web.http://1.usa.gov/X8PW7C