A new study led by Dr. Nicholas Cowan, an atmospheric physicist at the UK Centre for Ecology and Hydrology in Edinburgh, claims gases exhaled by humans when breathing contribute to global warming.

Sadly, this isn’t a parody.

“It has been reported that exhaled human breath can contain the greenhouse gases methane (CH4) and nitrous oxide (N2O), both of which have a much higher global warming potential than carbon dioxide (CO2),” the study reads.

“Where hydrocarbon chains (food types) are consumed by humans and turned into CH4 (and N2O from nitrogen intake), the global warming potential is no longer neutral, and human respiration has a net warming effect on the atmosphere,” it adds.

“We would urge caution in the assumption that emissions from humans are negligible,” the researchers stated.

Daily Mail reports:

For the study, the researchers investigated emissions of methane and nitrous oxide in human breath from 104 adult volunteers from the UK population.

Participants were required to take in a deep breath and hold it for five seconds, then exhale into a sealable plastic bag.

A total of 328 breath samples were collected and every participant had details recorded such as age, sex and dietary preference.

After analysing the samples, researchers found nitrous oxide was emitted by every participant, but methane was found in the breath of only 31 per cent of participants.

Researchers say those who do not exhale methane in their breath are still likely to ‘release the gas in flatus’ – in other words, by farting.

Interestingly, people with methane in their exhaled breath were more likely to be female and above the age of 30, but researchers aren’t sure why.

Concentrations of the two gases in the overall samples let the researchers estimate the proportion of the UK’s emissions are from our breath – 0.05 per cent for methane and 0.1 per cent for nitrous oxide.

Dr Cowan stresses that each of these percentages relate specifically to these respective gases, not all of the UK’s greenhouse gas emissions as a whole.

Researchers didn’t manage to find any link between gases in the breath and diets – although meat eaters are known to fuel the climate crisis in other ways.


The experts stress that their study only looked at greenhouse gases in breath, and so it does not provide an overall estimate of a person’s emissions footprint.

X users commented on the study:

The ‘scientists’ wrote in their conclusion:

The measurements carried out in this study allow us to estimate UK-scale emissions of approximately 1.04 (0.86–1.40) Gg of CH4 and 0.069 (0.066–0.072) Gg of N2O emitted in the form of human breath. Based on a sample population of 104 volunteers, we estimate that the methane producing (MP) population in the UK is 25% for those aged less than 30 years, and 40% for those aged over 30 years of age. We have found no correlation between diet and emission of CH4 and N2O in breath and recommend if future studies wish to assess this in more detail, that rigid dietary regimes are implemented to reduce the effect of heterogeneity of emissions in a given population. While emissions of CH4 and N2O account for only 0.05% and 0.1% of the total emissions in the UK national greenhouse gas inventories, respectively, we would urge caution in the assumption that emissions from humans are negligible. We report only emissions in breath in this study, and flatus emissions are likely to increase these values significantly, though no literature characterises these emissions for people in the UK. 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.

Read the full study at PLOS One.

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