Today an article appeared on the BBC news site about the dangers of second hand smoke. http://www.bbc.co.uk/news/health-17551568
What amazed me was the quote from Deborah Arnott, chief executive of Action on Smoking and Health (ASH):
“There is no safe level of exposure to tobacco smoke and children are at risk of a range of diseases such as asthma, ear infections, and potentially fatal meningitis as a result of breathing in second-hand smoke in the home or car.”
She seems to be implying that breathing in second hand smoke causes meningitis!
The absurdity of this is clear when you understand that there are two types of meningitis, one caused by bacteria and the other by a virus. Unless the laws of physics and biology have been re-written overnight, it is no more possible for smoke to transform into bacteria than it is for lead to turn into gold.
At first I thought this might be simply one of those correlation/causation fallacies that the health Nazis are so fond of. I.e. somebody had found that people breathing in second hand smoke had higher rates of meningitis than those who don’t and assumed a causal link. This is the same line of reasoning that would observe that more smokers travel on buses than non smokers and therefore smoking causes bus travel!
(The reality of course being that smoking is more common in the poorer sections of society and they are more likely to have to use the bus, because its cheaper than owning a car. The correlation is caused by another hidden factor, poverty)
Looking at the report there does appear to be an increased chance of contracting meningitis in a household that contains smokers, p88+
However, all of the studies quoted (apart from 1, which showed no difference) pre-date the following study funded by the Meningitis Research Foundation and published in 2006 titled:
Is it exposure to cigarette smoke or to smokers which increases the risk of meningococcal disease in teenagers?
It turns out that for smokers the probability of contracting meningitis is higher. Not because smoking causes meningitis but because smokers have higher carriage rates for the bacteria that cause meningitis than non smokers. (Now this could be because of smoking, or it could be because of the other lifestyle factors that smokers tend to have that non smokers don’t, including increased poverty, worse housing conditions, worse diet, increased levels of recreational drug use, more time huddled together in high physical contact small groups, etc, etc, etc.)
So what did this study in 2006 actually show about the dangers of getting meningitis from second hand smoke:
“Contact with smokers is associated with increased risk of MD in adolescents. This is more likely to be due to higher carriage rates in smokers than to exposure to smoke…
In epidemiological studies that assess risk from passive smoking, exposure to smoke should be differentiated where possible from contact with smokers.“
So the truth is not that exposure to second hand smoke causes meningitis in children.
The truth is that, unsurprisingly, contact with people who are carrying the meningitis bacteria increases the probability of contracting meningitis!