Joint Base San Antonio-Lackland fire emergency crews
recently responded to an alarm activation in a base housing area. Upon arrival,
fire alarms were sounding and the facility was being evacuated. The initial
report indicated a smoke detector had been activated within the facility.
After inspection, it was found an individual smoking an
e-cigarette caused the smoke detector to go off. With these items now in
regular use almost everywhere, it presents a new problem to firefighters and
users alike.
Although fires and explosions caused by electronic
cigarettes are rare, according to an article published by the U.S. Fire
Administration in October 2014
(http://www.usfa.fema.gov/prevention/outreach/smoking.html), more than 2.5
million Americans are using them and this number is growing rapidly.
The article states that 25 separate incidents of explosion
and fire involving an e-cigarette were reported in the United States media
between 2009 and August 2014, resulting in nine injuries, two being serious
burns when the devices exploded in the user’s mouth. In addition, 20 of the
incidents occurred while the battery was charging. It’s likely that there were
additional incidents not reported to the fire department and/or reported in the
media.
The e-cigarette, also called a personal vaporizer or
electronic nicotine delivery system, is a battery-powered device that simulates
tobacco smoking by producing a heated vapor which resembles smoke. These
devices have become an alternative to smoking, including among a growing number
of individuals who have never been smokers, but who enjoy the many flavors
and/or the experience of using e-cigarettes.
Patented in 2003, e-cigarettes have been sold in the U.S.
since 2007. According to a 2014 Department of Family and Preventative Medicine
at the University of California, San Diego
(http://tobaccocontrol.bmj.com/content/23/suppl_3/iii3.short) there were 466
brands of e-cigarettes and 7,764 unique flavors available for sale. They also
state the number of products has been increasing at a rate of 10.5 brands and
242 new flavors per month.
Annual e-cigarette sales have reached $2.5 billion dollars
nationally and the Statistic Brain website
(http://www.statisticbrain.com/electronic-cigarette-statistics/) reports that
as of July 13, 2014, there were 2.5 million e-cigarette smokers in America.
The devices have a heating element (an atomizer or
cartomizer) which vaporizes a liquid solution. Solutions (also called “juice”)
usually contain a mixture of propylene glycol (which increases flavor),
vegetable glycerin (which increases vapor), nicotine and flavorings. Some
juices provide flavored vapor without nicotine.
“Automatic” e-cigarettes activate the heating coil when a
user takes a drag from the device. Manual e-cigarettes have a switch that the
user depresses to energize the heating element to make the heated vapor.
Most manufactured devices have built-in timeout features
that prevent overheating and many have locking features to prevent the switch
from being activated in a pocket or purse. A light-emitting diode to simulate a
cigarette’s glow on the end is also common in e-cigarettes.
Media reports generally characterize these incidents as
explosions. The event occurs suddenly and is accompanied by a loud noise, a
flash of light, smoke, flames and often vigorous ejection of the battery and
other parts. Many of the media reports state that the battery or other
components of the device were ejected under pressure and “flew across the
room,” often igniting combustible items where they landed.
Most of the incidents resulted in ignition of nearby
contents, such as carpets, drapes, bedding, couches or vehicle seats. Users
were usually nearby when the incident occurred and they were able to extinguish
the fires while they were still small. One incident resulted in the loss of a
bedroom.
Eighty percent of the incidents reported occurred while
charging. A variety of charging sources were reported, such as laptop universal
serial bus ports, auto USB adapters, desktop computer USB ports and wall
adapter USB ports.
Not all USB ports are created equal, as the voltage and
current provided by USB ports can vary significantly. As a result, plugging an
e-cigarette into a USB port or power adapter not supplied by the manufacturer
may subject the battery to higher current than is safe, leading to thermal
runaway that results in an explosion and or fire.
Concern has been raised that the heating element inside the
e-cigarette could become an ignition source. Manufactured personal vaporizers
typically have built-in circuits to limit the time that the heating element can
be turned on, which prevents overheating and possible fires or injuries.
In the absence of independent safety testing of the
e-cigarettes, no assurance that these circuits will reliably perform their
safety function is available.
E-cigarettes are increasingly common and sales are growing
rapidly. The lithium-ion batteries used to power the devices can fail. Battery
failures, manifested as small explosions and fires, have occurred. Considering
the vast number of products in the field that use lithium-ion batteries,
however, it is clear that the failure rates are low.
For more information on smoking and fire safety, visit
www.usfa.fema.gov.
(Sources: U.S. Fire Administration; Department of Family and
Preventative Medicine at the University of California, San Diego; Statistic
Brain; Federal Emergency Management Agency; Ricardo S. Campos, Joint Base San
Antonio public fire and life safety educator, also contributed to this
article.)