Humans may be fueling global warming by breathing, a new study suggests.
“Exhaled human breath can contain small, elevated concentrations of methane (CH4) and nitrous oxide (N2O), both of which contribute to global warming,” according to research released last week in the UK journal PLOS.
The methane and nitrous oxide exhaled by humans make up about 0.1 of the UK’s greenhouse gas emissions, the writeup said.
The gases are in addition to the carbon dioxide that humans exhale.
The study, led by Dr. Nicholas Cowan from the UK Center for Ecology and Hydrology, involved 104 adult volunteers and found that nitrous oxide was breathed out by every one of them, while 31 percent exhaled methane.
Those who did not exhale methane in their breath still probably released the gas “ion flatus,” the study said, referring to burping and flatulence.
“We report only emissions in breath in this study, and flatus emissions are likely to increase these values significantly, though no literature characterizes these emissions for people in the UK,” the research team wrote.
“Assuming that livestock and other wild animals also exhale emissions of N2O, there may still be a small but significant unaccounted-for source of N2O emissions in the UK, which could account for more than 1% of national-scale emissions,” they added.
Gas concentrations in the study samples allowed researchers to estimate that human breath accounts for 0.05 percent of the UK’s methane emission and 0.1 percent of nitrous oxide.
The study did not reveal a link between exhaled gases and diet.
“Concentration enhancement of both CH4 and N2O in the breath of vegetarians and meat consumers are similar in magnitude,” the researchers said. “Based on these results, we can state that, when estimating emissions from a population within the UK, diet or future diet changes are unlikely to be important when estimating emissions [exhale] across the UK as a whole.”