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We hear about the overload of carbon dioxide in the atmosphere, but what percentage of this comes from human exhalation?

Nick Canning

Londonderry, UK

If we roughly estimate that an average person exhales about 0.66 kilograms of CO₂ in a day, this means that a world population of about 7 billion people will exhale around 1.7 gigatons of CO₂ into the atmosphere each year.

Meanwhile, the estimated total CO₂ emissions per year from global fossil fuel usage in 2019 was about 40.5 gigatons. This means human exhalations produce about 4 per cent of the amount of CO₂ that is emitted by burning fossil fuels.

Most of the problems with excessive carbon emissions result from powering society through our massive use of fossil fuels, rather than the worldwide exhalations that power our own bodies.

Keith Ross

Villembits, France

The carbon dioxide we breathe out is used by plants to grow through photosynthesis, as part of the carbon cycle. Therefore, it doesn’t matter how much CO₂ we breathe out. We are adding to the CO₂ in the atmosphere when we dig up and burn fossil fuels.

@miclagioia via Twitter

Human exhalation is part of the natural cycle of gases entering and leaving the atmosphere, so it doesn’t produce any overload per se. But we do contribute via our diets, as food production causes about a third of carbon emissions.

@krishna97318875 via Twitter

As much as possible, humans shouldn’t exhale, or they can attach a carbon solidifier to their nose and clean their nose every hour or so to protect the environment.

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