Second Hand Smoke

It is hard to argue that anyone does not know about the harms smoking can cause given that it is so widely advertised on the packets, discussed in schools and banned from establishments in many countries. However, it appears that exposure to second hand smoke does not receive the same attention. Yet studies show that exposure to second hand smoke can have serious effects. In the hopes of shedding some light on this topic, we have decided to consider the findings a recent study from the established Karolinska Institute in Sweden.

The study, which was published in Pediatrics, was a prospective longitudinal cohort study that followed the participants over 16 years. In total 4089 children were included from birth until their 16th birthday. The researchers provided questionnaires to their parents, which measured parental smoking habits, lifestyle factors and symptoms of allergic disease. The key findings indicated that individuals who had been exposed to second hand smoking had a higher risk of developing asthma. This was also the case for individuals who had been exposed during infancy. In contrast to that, exposure to second hand smoking in later years appeared to relate to increased risk of developing eczema. Based on this the authors concluded that their findings support previous research in this field, but that the age of exposure affects what illness a person may develop.

There are many aspects of this study that make it robust. Firstly, it is worth noting that the extensive sample had a low attrition rate throughout the life of the study. Secondly, the factors considered were quite broad including indoor environmental exposures, maternal smoking during pregnancy, socioeconomic status, parental allergies and lifestyle factors. Lastly, it appears that this is one of the few studies that has identified a dose-response relationship between second hand smoking and development of asthma or eczema. Essentially, it suggests that the higher the exposure, the higher the likelihood of developing these conditions.

As with any study of this magnitude, there are also limitations that are worth bearing in mind. Perhaps what stands out the most is the fact that the parents were reporting on questionnaires. This means that they could have played down their own smoking habits or misunderstood the classification of some questions. However, the researchers appear to have compared this with other measurements. Similarly, some have argued that the findings from the study may only be applicable to Nordic populations. However, it is more likely to be applicable to European and American populations due to the similarity in lifestyle. Lastly, although the study is prospective, it should also be stressed that it cannot establish the cause. Having said that, it is as close as it can get to a topic like this without breaching ethical standards.

Overall it is clear that the study conveys the important message of avoiding second hand smoke especially during pregnancy. It is our hope that this message is given its due weight.

You can read more about the dangers of second hand smoking here.

© 2014 Doncaster Health