Monday, 12 October 2015 17:20

By Dr Farsalinos

A new study was published by a group of Spanish researchers in the journal Current Environmental Health Reports (free access to the full text here). The study reviewed the literature and also made an observational study in a home of a vaper, a home of a smoker and two smoke-free and vape-free homes in order to compare the levels of PM2.5 exposure.

In the study abstract, they present the results of their observational study: “In the observational study, the PM2.5 median concentration was 9.88 μg/m3 in the e-cigarette user home and 9.53 and 9.36 μg/m3 in the smoke-free homes, with PM2.5 peaks concurrent with the e-cigarette puffs”. Strangely however, in the conclusion part of the abstract they mention: “Conclusion. Both the literature review and the observational study indicate that e-cigarettes used under real-conditions emit toxicants, including PM2.5”.

It seems that the conclusion is contrary to the findings of their small observational study. Indeed, the published figure which displays the PM2.5 concentration in homes clearly showed that the levels in the vaper’s and the non-smoker’s home are virtually indistinguishable, besides some very small peaks at the time of taking e-cigarette puffs. At the same time, levels of PM2.5 in the smoker’s home were about 60 times higher.

FIGURE REMOVED DUE TO COPYRIGHT ISSUES, BUT IT AVAILABLE WITH FREE ACCESS HERE

It is easy to identify the huge differences not only on background levels but also on the spikes associated with smoking tobacco cigarettes (A, B and C), compared to the minimal spikes when taking e-cigarette puffs (asterisks).

The literature review included a study by Schober et al., the only study till now which found polycyclic aromatic hydrocarbons (PAH) emitted to the environment from e-cigarette use. I submitted a letter to the editor concerning this study, in which I explained that a major methodological error was that they assessed baseline environmental levels on a separate day from the e-cigarette use, and provided references that PAH levels may change significantly between days or even within the same day. Moreover, some of the studies presented in the review assessed the content in exhaled e-cigarette aerosol in small glass chambers (8-10L volume), which of course is a very low volume compared to a volume of several m3 of a room where the exhaled aerosol is dispersed under realistic conditions.

The Spanish study is a classical and obvious example of misinterpretation of study findings. Their conclusion should be that PM2.5 levels in a home of a vaper are hardly distinguishable from a home of a non-smoker, and significantly lower from the levels in a smoker’s home. Moreover, they once again ignore that the composition of the PM is of vital importance in determining any risk. Particles of combustion products like emitted from tobacco cigarettes and associated with environmental pollution are very different to the microdroplets of PG, VG, water and nicotine that compose the e-cigarette emissions.