The latest alarm over climate change is that inhalers used by asthmatics - you know, to stop them dying? - produce the sort of emissions which contribute to that climate change. And sure enough they do, as do near all the other things we do to stay alive.

The important question here is always, well, how much? And what is the cost of those emissions and what the benefit?

The National Institute for Health and Care Excellence (Nice) has issued new guidance urging sufferers, where possible, to avoid using the most popular type of inhaler, known as a metered dose inhaler (MDI).

Making up around 70 per cent of inhaler prescriptions - approximately 26 million a year - MDIs contain propellants known as hydrofluorocarbons, which are powerful greenhouse gasses.

The first time Nice has assessed the carbon footprint of a recommended device, the body calculated that five doses from a MDI have the same carbon emissions as a nine-mile trip in a typical car.

Fortunately we’re given the numbers here to be able to work out what that cost is. Using the numbers the Stern Review gave us, the social cost of emissions is $80 per tonne Co2-e. And yes, that’s using Stern’s “I’m going to assume worse than the IPCC does” and also his heterodox ideas about discount rates.

One source tells us that the average (new) car does 52 mpg which we’ll take as that average. 9 miles is thus roughly one sixth (17%) of a gallon. A gallon produces some 9 kg of CO2. We’ve thus $80 x 1/6 x 0.009 which is about 12 cents or perhaps 10 pence. We do hope we’ve got the right number of zeroes there etc.

The benefit is that someone doesn’t choke to death on their own airways, or suffer the experience of thinking they’re about to. Yes, that’s worth 10 pence of damage to the planet in some century or so hence, tough luck Flipper. Go ahead and use your inhalers as you wish therefore. Maybe not pop them off just for fun and the lulz but otherwise don’t even worry about it.

Of course, if we had the only climate change policy that makes sense - assuming that we need one at all - that carbon tax then this would already be incorporated into everyone’s incentives as to what actions they take. We wouldn’t need boards of worthies to tell us about this, we’d already know.