Passive smoking - are smokers killing the rest of us?

I am a little bit puzzled. We seem to be experiencing some problems lately with the air we breathe. In brief, and not to put too fine a point on it, we are atmospherically challenged. People living in large cities have a much greater chance than the rest of us of having heart attacks, and on days when there is a temperature inversion the number of heart attacks increases significantly. Children who live by the side of main roads have a much higher chance than others of suffering from asthma. We are all breathing in all kinds of interesting chemicals, a gaseous cocktail which includes some choice ingredients. Some of these are highly carcinogenic like benzene, one of the by-products of using unleaded petrol.

And yet what is it that we really seem to be getting our knickers in a twist about? Cigarette smoke.

This seems to me to be like getting upset about a flea when there is an elephant sitting on your dog.

Now I think that the most die-hard (no pun intended) smoker will admit that it's not actually good for you (something that the advertisers forty years ago used to maintain!). So it's not surprising that people are trying to stop cigarette advertising and trying to prevent young people from starting in the first place. Indeed, it is certain that tobacco is the among the most dangerous of the hard drugs. So one can only praise the efforts of the anti-smoking lobby.

However, where I take issue with them is when they start warning us about the perils of 'passive smoking'. It is a powerful phrase, and a copywriter would have been proud to have come up with it. It manages to suggest that the those of us who are non-smokers are being forced by the addicts into sharing their habit. And that in turn suggests that so-called passive smokers are in danger of contracting the diseases that tobacco smoke is known to cause among smokers.

In fact a recent item on the television news in this country stated that it had been just discovered that 'passive smoking' was much more dangerous than had been supposed up to now, and that 'passive smokers' were in serious danger of contracting these diseases.

I wonder who these 'passive smokers' are? The only ones I definitely know about were those poor beagles who were forced to smoke in the cause of research. This, perhaps, is a point worth labouring a bit. According to the American Heart Association, "Among nonsmokers who were never exposed to secondhand smoke, arteries thickened 40 micrometers over a period of three years" as opposed to nonsmokers who were exposed to secondhand smoke, whose arteries thickened to a greater extent. But wait a minute there. Non-smokers who were never exposed to secondhand smoke? Where did they get those from? This is the crucial issue here. Until you use a sound statistical method, everything is speculation, and the statistical method falls down badly when it comes to passive smoking.

That particular bit of research is one which I don't find altogether convincing, at least from the report I have read of it (USA Today). We are presented with 5 separate groups:- nonsmokers never exposed, nonsmokers exposed, ex-smokers never exposed, ex-smokers exposed and smokers. The thickening is reported in micrometers as being, respectively:- 40, 45, 50, 55, and 60. A little too neat for my liking. Especially on a reported sample of 8,415.

But as I say, the real issue so far as I am concerned, and the one that really invalidates all the recent statements about passive smoking, is the statistical one.

Because of human frailty, and the unconscious (or sometimes conscious) tendency to manipulate figures to produce the results we want to see, there is a very strict method of gathering data for scientific studies.

I have to say at the outset that I do not know a lot about statistics. But I do know that when you are testing for a particular thing, you have to be at pains to eliminate any other factor which might contaminate your results. In other words, when you compare two groups of people, you have to make the comparison in such a way that there is no difference between them, apart from the factor in which you are interested.

It seems to me there are many factors which could lead to false results. For example in this country at least there are social factors which influence smoking. Smokers tend to be in the lower income groups, and this means that they are subject to all the other influences which could affect their health. They are more likely, for example, to have an inadequate diet. They are more likely to live in damp, unhealthy houses. So when statistics show that the children of smokers are more likely to spend time in hospital with respiratory diseases, this doesn't mean that they are caused by 'passive smoking'. There might be a link, but that link does not have to be the obvious one!

So when you are comparing these two groups, you have to isolate the one factor, which in this case is being exposed to cigarette smoke. Then there comes the difficulty of where you draw the line. You have to decide which people come into the category of 'passive smokers' and which do not. This means drawing up some kind of criterion for exposure to cigarette smoke. Do you allow people who have only rarely come into contact with cigarette smoke, or do you only include those whose contact is fairly constant? How do you quantify the degree of exposure?

Of course, when you do any of the above you are introducing a prejudice into your results, because the figures should not depend upon any decision that you make.

In fact the only proper way of carrying out the exercise, it would seem to me, would be to use two groups, one of which contained people who had never in their lives come into contact with cigarette smoke.

This would mean that you would have to get this group from somewhere like Outer Mongolia, or from some kind of community which was isolated from general society in some way, like a religious order. But if you take either of these alternatives, you are immediately introducing an enormous distortion, because the environmental factors acting upon this group will be entirely different from the other one.

For this reason, it would seem to me that there is no reliable way of assessing the effects, if any, of 'passive smoking'.

It also seems to me that the people who make these claims about so-called passive smoking tend to be a little lax about the methods they use to get their message across.

A document from the Rose Medical Center in Colorado is typical of the kind of literature disseminated by those who wish to ban smoking in public places. The document claims to give the facts, taken from highly reliable sources. Ok. One of the facts is that the smoke that non-smokers are exposed to is "sidestream" smoke, which is produced by low-temperature burning, and is therefore more full of dangerous substances. It is claimed both that the actual smoker does not absorb as much of this smoke as other people, and that it does him less harm because his airways have adapted to cigarette smoke. The first of these arguments does not hold water; any smoker is aware that they are absorbing much more 'sidestream' smoke than others (and as a reformed smoker I can vouch for that). The second argument is one which is made without, so far as I am aware, any evidence to support it, and I would be interested to know how one's airways can adapt to deadly carcinogenic chemicals! In fact it paves the way for the most extreme of the anti-smoking lobby's arguments, that passive smoking is actually more harmful than the real thing!

We are told in the report that the smoke from cigarettes contains more than 40 documented carcinogens.

Now think about that for a moment. Cigarette smoke is the smoke produced when burning the cured leaves of a plant. That's all. It's just a plant like any other plant. If a cigarette can produce all those deadly chemicals, think of how many more must be produced by your garden bonfire! (Not to mention the factory next door!) Of course the issue is not the number of potentially toxic chemicals produced, but their concentration. We are told that many of these have no safe exposure limit. If that is the case, then we must have all been exposed to a deadly menace when lighting our bonfires.

When you read some of these reports, it would seem that smoking and 'passive smoking' cause so many deaths that not many of us die of anything else!

It is ridiculous coming out with all these spurious statistics. In point of fact we don't know whether so-called passive smoking causes harm to people. I am not saying that 'passive smoking' is harmless - just that we have no way of knowing.

However, the indications that it does not cause harm are rather more convincing that the contrary ones.

It has been stated by the anti-smoking lobby that a 'passive smoker' who lives in an environment in which other people smoke, breathes in the equivalent of one cigarette a day. It has already been shown that the health risk to smokers diminishes the fewer cigarettes they smoke. By the time they get down to ten a day, the health risk is unmeasurable - it gets lost in the 'noise'. If ten a day doesn't cause a significant health risk, then how can one a day? And incidentally how did they establish the volume of smoke inhaled by a 'passive smoker' over the course of a day?

It is the possibly the ludicrousness of their unsubstantiated argument that presumably has caused parts of the anti-smoking lobby to claim that smokers don't experience passive smoking themselves, and that in any event they are more inured to it.

It seems to me that in their anxiety to spread their non-smoking message - and not many people could disagree with the message that smoking is bad for you - the anti-smoking lobby is resorting to more and wilder claims. Indeed there are serious doubts (raised by the Congressional Research Service, and expressed by Senator d'Amato in the American Senate on 15th November 1995) that the methods used by the Environmental Protection Agency and the Occupational Safety and Health Administration were seriously flawed.

In Australia documents have been published which indicate that their National Health and Medical Research Council were falsifying their report into so-called passive smoking by deleting data which did not support their recommendations for a ban in public places. A public health professor in Sydney University has stated: "Journalists looking at that table ... will be hard pressed to write anything other than 'Official: passive smoking cleared - no lung cancer'."

As I said earlier, there is a natural human tendency to manipulate data to support our opinions, and we should take care to be sceptical of anything which is not authenticated, and which does not conform to the strictest of statistical methods.

There are two reasons why all this worries me

One of them is that it distracts public attention away from the really serious problems concerning the quality of the air that we breathe. The fact that children living alongside main roads have a far greater incidence of asthma is a simple statistic, and one that cannot be argued with, any more than can the fact that in Britain 5,000 children a year are seriously injured or killed in traffic accidents.

'Passive driving' really is bad for you, but we tend not to reserve our moral censure for drivers, perhaps because so many of us drive or use cars.

A recent study showed that environmental pollution means that we all carry a burden of about 500 chemicals in our bodies which would not have been found in people prior to 1920. Many of these are carcinogenic, and indeed recent research has indicated that some of them might be a contributory factor to breast cancer.

For God's sake, let's get worried about the right things!

Another thing that worries me about this is that it is going hand-in-hand with a general movement towards intolerance in our society. We seem only too eager these days to jealously guard our own 'rights' and deny those of others. Living in a crowded environment we have to learn to be tolerant. It is inevitable that the things other people do will at times be inconvenient to us. That doesn't mean we should take an attitude of moral superiority to them, and certainly doesn't give us the right to pretend that they are doing us serious harm.

Originally I supplied, as a kind of bibliography, a list of sites that were used in the preparation of this article. However, unfortunately all of them have now disappeared.

Some responses Some responses I have received