Breathless reports of e-cigarette battery explosions have appeared recently in the Journal of the American Dental Association (here) and Cornea (here). The latter article, alluding to a “number of media reports,” claimed that “e-cigarettes pose a significant public health risk.” Clive Bates labeled that claim “inappropriate and alarmist” in his excellent PubMed Commons comment (here).
Bates explained that “Risk is a quantitative concept or it is meaningless… Claims that products or behaviours cause significant public health risks need to be proportionate and reflect both absolute risks (how much harm is caused) and relative risks - i.e. set in appropriate context by reference to risks arising from other common products and activities.”
In other words, the risk of e-cig accidents should be assessed in relation to smoking-related accidents.
According to the Federal Emergency Management Agency (FEMA), “Twenty-five separate incidents of explosion and fire involving an e-cigarette were reported in the United States media between 2009 and August 2014…nine injuries and no deaths.” (here) The agency concluded: “Fires or explosions caused by e-cigarettes are rare.”
In contrast, the FEMA chart above shows that smoking caused 40,000 residential fires, 1,665 fire deaths and 4,550 fire injuries over roughly the same period (source here). Clearly, a switch from combustible to electronic cigarettes will substantially decrease fire hazards as it reduces the 400,000+ annual deaths from cancers, cardiovascular and lung diseases.
E-cigarettes have lithium-ion batteries. Battery explosions and fires, which also occur with cell phones and laptop computers, are rare events that can be prevented with quality control in manufacturing and with responsible use -- charging with manufacturer-recommended power adaptors and handling and storing appropriately, for example.
In any rational analysis, the real public health hazard is smoking.