Imagine allowing your staff to take every Friday afternoon off. It would be popular, no doubt, but would it be good for your business? I ask because that’s effectively what businesses do when they allow smokers time to nip outside for a smoke.

We have been examining the cost of smoking for a primary care trust in London, adapting a model that we first created some years ago for the NHS in the West Midlands (see www.smokingcosts.org.uk). Our calculations come up with the striking finding that an average smoker spends 11 per cent of their working day on smoking breaks. For this London borough, that equates to £65 million every year in lost productivity.

And all that’s on top of time lost for hospital appointments and days lost in sickness, which we calculated to be worth another £28 million. A total cost to businesses in this area of some £93 million every year.

Translate that into equivalent figures for a big corporation like Tesco, with 260,000 employees in the UK, and (if all our assumptions held good for Tesco) the cost to them would be around £110 million a year. Big money.

And it works at an individual level too. The outgoing government made a point of increasing tobacco taxes faster than inflation, with the result that among the poorest 10 per cent of people in the country, an average smoker spends over 10 per cent of their income on smoking. That’s a huge cost to them.

There are lots of good reasons for stopping smoking – and for employers to take steps to encourage their staff to stop. I’ve never understood why the economic arguments aren’t used more.