Medical Research: What are the main findings of the study?
Dr. Cherrie: We set out to bring together measurements of fine particle levels in homes where smoking takes place, to compare these with smoke-free homes and then to estimate how much of these fine particles are inhaled by people at different stages in their life. We also wanted to look at the exposure to particles of non-smokers living with smokers and compare this with the exposure of people living in heavily polluted major cities around the world.
Medical Research: What was most surprising about the results?
Dr. Cherrie: The levels of fine particles, called PM2.5, in homes where smoking takes place were, on average, three times higher than the World Health Organisation (WHO) recommends and in a quarter of the smoking homes where we measured the concentrations were more than 11 times higher than recommended levels. A considerable proportion of smokers’ homes had air pollution levels that were the same or higher than the annual average PM2.5 concentration measured in Beijing. What is surprising is that, the mass of these fine particles inhaled over a lifetime is not that great. A non-smoker living with a smoker will only inhale about 5g more than a non-smoker living in a smoke-free home in Scotland, that’s just a little more than a teaspoon of fine smoke particles. However, we know from epidemiological evidence that these small amounts of inhaled particles can have a substantial effect on the risk of developing diseases of the cardiovascular and respiratory systems.
Medical Research: Medical Research: What should clinicians and patients take away from your report?
Dr. Cherrie: The message is pretty simple really. Smoking in your home leads to really poor air quality and results in concentrations of fine particles – that you can’t see – and that would cause real concern to us if they were found outside. Making your home smoke-free is key to reducing your exposure to PM2.5; for non-smokers who live with a smoker the impact of implementing smoke-free house rules where smoking is only done in the garden or some other outdoor place would reduce their daily intake of PM2.5 by 70% or more.
What recommendations do you have for future research as a result of this study?
Dr. Cherrie: We need to better understand how to help smokers make their homes smoke-free. Smokers want to do what is best for the health of their families and those they love. Providing air quality feedback can help to educate and motivate smokers on how they can improve the air in their home. Developing low cost, easy to understand feedback to households with smokers would be a step forward to reducing population levels of exposure to PM2.5 and second-hand smoke. We are actively working on this type of approach.
S. Semple, A. Apsley, T. Azmina Ibrahim, S. W. Turner, J. W. Cherrie. Fine particulate matter concentrations in smoking households: just how much secondhand smoke do you breathe in if you live with a smoker who smokes indoors? Tobacco Control, 2014; DOI: 10.1136/tobaccocontrol-2014-051635