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Hallett_Hermann_Electronic Cigarettes

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IAQA 18th Annual Meeting & Indoor Environment and Energy Expo (IE3) The views and opinions herein are those of the volunteer authors and may not reflect the views and opinions of IAQA. The information is offered in good faith and believed to be reliable but it is provided without warranty, expressed or implied, as to the merchantability, fitness for a particular purpose or any other matter. Brief History of E-cigarettes E-cigarettes, also known as Electronic Nicotine Delivery Systems or ENDS, Electronic Cigarettes, Electronic Smoking Devices (ESDs) e-cigs, and e-hookah, are a class of products intended to deliver nicotine-containing aerosol (incorrectly commonly called ―vapor‖ to a user by heating a solution typically comprised of propylene glycol and/or glycerol (glycerin), nicotine and flavoring agents.The first concept of an electronic cigarette was patented in 1965 by Herbert A. Gilbert as a smokeless non-tobacco cigarette. Subsequently, an aerosolized, high-frequency e- cigarette was patented in China by Chinese pharmacist, Hon Lik and Ruyan Technology. It entered the market in 2003 and was patented internationally in 2007.(4) (8). In early 2014 there were 466 brands and 7,764 unique flavors in e-cigarette products. The products are widely available on-line and in retail outlets throughout the world. (8) In the United States, retail outlets are growing at an alarming number with growth rates estimated at 30% or more. How do they work? E-cigarettes contain a liquid, typically propylene glycol and/or glycerol that include varying amounts of nicotine (e.g., 0 to 36 mg/mL) as well as flavorants. A wicking material is used to transport the liquid by capillary action from a reservoir to the heater. When the user draws on the e-cigarette, a sensor detects the draw and a microprocessor activates the heater, which vaporizes the fluid to produce a saturated vapor at an elevated temperature (i.e., > 350°C [662°F] in the center of the heating unit). Propylene glycol, glycerol, and nicotine are liquids with relatively high boiling points: propylene glycol (188°C [370°F]), glycerol (290°C [554°F]), and nicotine (247°C [477°F]). Consequently, the vaporized fluid immediately condenses upon leaving the heating element, forming an aerosol of submicron spherical liquid droplets with the visible appearance of smoke or fog.(9) See Figure 1. FIGURE 1: Schematic of the typical components found in an e-cigarette. ASHRAE 2014 reprinted with permission LED: Lights Up When the User Draws on the E-Cigarette Battery Microprocessor Controls Heater and LED Heater Vaporizes E-cigarette Fluid from Heated Wick Sensor Detects When User Draws Mouthpiece (Condenser). Vapors Condense Into an Aerosol of liquid sub-micron droplets of E-cigarette Fluid

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