Every day, cows release methane gas into the air. From you know where. But methane is also found somewhere else. Yesiree, in cigarette smoke.
"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, 19 Nov. 2001. Report.http://cancercontrol.cancer.gov/tcrb/monographs/13/m13_complete.pdf
"Methane Background Information, Where Do We Find Methane?" ARM Climate Research Facility. Web.http://1.usa.gov/128GeX0
"Air Emissions." Pennsylvania Department of Environmental Protection. Web.http://www.dep.state.pa.us/dep/deputate/pollprev/iso14001/bpmanual/CAirAll.htm