Q: Will an occasional cigarette damage your health?
A: Quite possibly. Every cigarette increases your risk of smoking-related diseases.
Are you one of the 12% of smokers who would classify themselves as smoking only 'occasionally' – perhaps weekly or less?
Or maybe you see yourself as one of the 17% who describe themselves as 'social' smokers: you don't smoke at home, but you do light up when you are out with friends.
Either way, you may think that your risks of getting sick from smoking are negligible. But is that the case?
Well, Professor David Currow of the Cancer Institute NSW says your risk is linked to how much you are smoking – but crucially there is no safe level.
"Smoking is a continuum ... the more you smoke, the more effect it will have on your health," he says.
"Furthermore, we know that [the negative health effect] is cumulative across your life".
Studies can now measure the immediate changes in our bodies as we smoke a single cigarette, from a rise in blood pressure to a change in the gases in our blood stream.
Here's what happens when we smoke a cigarette:
- Although we may feel more relaxed as we smoke, our blood pressure and heart rate both increase, the heart pumps differently, and the blood flow to the capillaries decreases.
- Blood carbon monoxide levels increase. "Carbon monoxide takes the place of oxygen in some of your red blood cells, and it sticks on to the red cells for days, preventing oxygen from being carried by these cells", warns Currow.
- Other changes happen in our airways: the little finger-like cilia which keep airways clear of phlegm are 'stunned' by chemicals in the smoke and tiny muscles in our airways contract, constricting them.
- There are also measurable changes in the immune system.
These and other changes have a cumulative effect and over time they can eventually lead to cancer (including cancer of the lung, pancreas, oesophagus, and bladder) as well as non-cancerous, but potentially lethal, conditions such as heart and vascular disease and lung diseases like emphysema.
And it's not just cancer and the health of your heart and lungs that you have to worry about.
A recent review of several studies found that light smoking was connected to a host of other illnesses: cataracts, reduced fertility, an increased risk of an ectopic pregnancy (where the pregnancy develops outside the uterus) and weak bones.
Perils of social smoking
The other problem with being an occasional or social smoker is that you could already be smoking more than you realise – or on a slippery slope to heavier smoking.
Professor Wayne Hall of the University of Queensland says, based on data from the 2004 National Drug Strategy Household Survey, most people who described themselves as 'social' smokers lit up daily.
About half of them were having more than five cigarettes a day and a third of them were having more than 10 cigarettes a day. Currow points out that, since social smokers often combine smoking with drinking, it's easy to lose track of the number of cigarettes they've smoked.
'Occasional' smokers lit up only once a week or less often, according to the survey. These people were quite different to social smokers, as they usually smoked at home, they tended to be married or in a de-facto relationship and some said they felt they had 'already quit smoking'.
However, Currow fears that once addicted to the nicotine in cigarettes, both social and occasional smokers may move to heavier smoking.
"At present we have no way of knowing how readily a person will become addicted to nicotine until after the event – when they have become addicted," he says.
"Nicotine is one of the most addictive substances known to mankind, so experimenting in that space is not smart."
The good news
Medical experts like Currow are convinced that the only safe strategy is not to smoke at all.
The good news is that as soon as we stop smoking our body starts recovering.
Within 12 hours of our final cigarette, blood carbon monoxide levels are much lower, and a year later our risk of coronary heart disease will be half what it was as a smoker.
If we quit before the age of 35, our life expectancy will be much the same as someone who has never smoked. But whatever age you are, there are a myriad of benefits to be had in quitting. What are you waiting for?