Are electronic cigarettes harmful to innocent bystanders? The question remains unanswered. The number of substances smokers exhale, and exactly what those substances are, are brought to light in a new study.

Electronic cigarettes have become very popular in recent years. Approximately two million people in Germany have already changed over to the “vapor cigarette”, which many see as a healthy replacement to classic cigarettes.

However, many political voices are warning about potential health risks associated with the e-cigarette, suggesting that long-term outcomes remain unknown. Previous studies have shown mixed conclusions.

Research presented earlier this year at the European Respiratory Society’s Annual Congress 2012 suggested that electronic cigarettes do cause lung damage. They revealed that using an e-cigarette resulted in an increased airway resistance which lasted for 10 minutes.

By conducting a new independent study, researchers at the Fraunhofer Institute for Wood Research WKI in Braunschweig, strive to establish objectivity into this heated debate. The goal of the scientists involved was to explore whether or not e-cigarettes pollute the air around them, thus affecting innocent bystanders.

An e-cigarette is made up of an atomizer, a battery, a heating coil and a reservoir for the liquids used for producing vapor. These liquids heat up in the atomizer and are then vaporized at around 65 to 120 degrees Celsius. The e-cigarettes are activated by the smoker pressing the button or by suction. Liquids can come with or without nicotine and also with flavors such as amaretto, vanilla, almond, or apple.

Propylene glycol is the most common solvent and creates the atomized mist, that looks like smoke, when exhaling. Unlike regular cigarettes, which continuously produce smoke as the tobacco burns, the electronic equivalent only lets out volatile substances when it is active.

Dr. Tobias Schripp, scientist at Fraunhofer WKI and co-author of the study says, “In the e-cigarette, vaporized substances create an aerosol of ultrafine particles which become even finer when inhaled into the lungs. These tiny nanodroplets disperse over time. In contrast, the combustion process discharges solid particles that can remain in the surrounding air for a considerable time.”

The experts conducted a series of test chamber measurements to examine emissions of volatile organic compounds (VOCs), ultra fine particle, and formaldehyde, with specific focus on the concentration, quantity, and distribution of particles. Tests were done using participants in an 8-cubic-meter test chamber where they compared regular cigarettes with e-cigarettes consisting of a variety of liquids.

To figure out how the distribution of particles changes over many minutes, and the amount of propylene glycol released long-term, the vapor was pushed directly into a 10-liter glass chamber. The test was done on several different kinds of e-cigarettes, all containing the same liquid.

“In general, the emissions of VOCs and ultrafine particles when smoking an e-cigarette were lower than the equivalent emissions from a standard cigarette”, said Schripp.

Additionally, the researcher and his colleagues were unable to find any formaldehyde emissions from the e-cigarette. Regular cigarettes, on the other hand, surpassed the guideline value of 0.1 ppm (parts per million) for indoor air quality under the given test requirements. Vaporized propylene glycol was given off from both tobacco cigarettes and e-cigarettes. Pulmonologists are afraid this solubilizing agent can bother the airways when inhaled in big quantities.

Schripp explained:

While it is true that the electronic cigarette contributes less to indoor air pollution than tobacco cigarettes, it is not entirely emission-free. Consequently, it seems reasonable to assume that bystanders are exposed to the released vapor and thus ‘passive vaping’ is possible.”

The authors also criticized the product labeling which sometimes gives inadequate or vague information on the liquids used. Therefore, many times, e-smokers have no good way of knowing what potentially harmful substances they are inhaling and exhaling.