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Historical context, philosophy and principles of environmental health
Published in Stephen Battersby, Clay's Handbook of Environmental Health, 2023
As others have written in great detail about the public health controversy that JUUL Labs, Inc. has created [12] in utilising a proprietary nicotine salt-based e-liquid formula [13], JUUL framed its new aerosol nicotine delivery system as a safe alternative to traditional, combustible tobacco products, with the potential of mitigating the lung-related illnesses and death associated with smoking [14]. Yet, while little was known about the short- and long-term health effects of inhaling nicotine aerosols, JUUL’s vaping products were rushed to mass production without substantive toxicological testing to ascertain its health safety [15]. Even now, more than a decade after e-cigarettes were introduced on the market, the Johns Hopkins Ciccarone Center for the Prevention of Heart Disease admits that vaping exposes users to various chemicals that we don’t yet understand and that are probably not safe [16] – aerosols that the Surgeon General underscores may contain harmful and potentially harmful chemicals, including nicotine; ultrafine particles that can be inhaled deep into the lungs; flavoring such diacetyl, a chemical linked to a serious lung disease; volatile organic compounds such as benzene, which is found in car exhaust; and heavy metals, such as nickel, tin, and lead.40[17–21]
Boiling
Published in Efstathios E. Michaelides, Clayton T. Crowe, John D. Schwarzkopf, Multiphase Flow Handbook, 2016
e CHF in subcooled ow boiling is reached in one of the following three ways (Tong and Hewitt, 1972): 1. A dry patch forms on the heater surface a er a bubble has departed. e local temperature in some cases rises to a point where the water fails to rewet the surface, leading to the CHF condition. 2. A thin layer of bubbles is formed on the wall at moderate heat and mass uxes. e neighboring bubbles then cluster together to form a vapor layer underneath the bulk liquid and restrict liquid access to the heater wall. 3. A slug ow is observed under certain conditions at low mass uxes. e liquid lm surrounding the vapor bubble evaporates and dries out. If the vapor bubble is su ciently long, the heater wall becomes heated during the passage of the bubble and leads to the CHF condition. Celata and Mariani (1999) summarize the previous models in the following ve categories: (1) boundary layer ejection model, (2) critical enthalpy in the bubble layer model, (3) liquid ow blockage model, (4) vapor removal limit and near-wall bubble crowding model, and (5) liquid sublayer dryout model. A brief description of each of the mechanisms is given as follows (Kandlikar, 2001b). 8.2.8.1.1 Boundary Layer Ejection Model. is model was originally proposed by Kutateladze and Leont'ev (1966). e boiling mechanism is compared with the injection of a gas stream into the liquid ow through a permeable plate. e ejection of bubbles into the mainstream is postulated to be the cause of the boundary layer separation at the heater surface. However, the photographic study conducted by Mattson et al. (1973) does not show any abrupt changes or high-velocity vapor ejection in the macroscopic structure of the ow near the CHF location. 8.2.8.1.2 Critical Enthalpy in the Bubble Layer Model. is model was proposed by Tong et al. (1966). ey assumed that a layer of small bubbles owing adjacent to the heater surface traps the liquid between the bubble layer and the heated surface. is bubble layer separates the trapped superheated liquid layer from the mainstream. ey postulated that CHF condition is reached when this superheated liquid layer attains a
Multicomponent and Adiabatic Absorption Columns
Published in Alan M. Lane, Separation Process Essentials, 2019
The reference state for the ethanol and carbon dioxide is vapor/gas at 30°C so their enthalpies in the liquid will include both sensible and latent heat. The hypothetical path for ethanol is E (vapor, TF) → (vapor, TB) → E (liquid, TB) → E (liquid, T).
Laboratory determination of gravimetric correction factors for real-time area measurements of electronic cigarette aerosols: Part 2
Published in Aerosol Science and Technology, 2023
Sinan Sousan, Qiang Wu, Yoo Min Park, Sarah Fresquez, Nathaniel Batts, Nicole Bertges, Carol A. Johnston, Heather Tunnell, Jack Pender, Eric Soule
ECIGs work by aerosolizing liquid (e-liquid) containing nicotine, propylene glycol (PG), vegetable glycerin (VG), nicotine, and flavorants (Breland et al. 2017; Walley et al. 2019). When users puff an ECIG, a sensor is activated that stimulates a heating coil to vaporize the e-liquid into a nicotine-containing aerosol (Czogala et al. 2014; Walley et al. 2019). E-liquid, once aerosolized, is subjected to both evaporation and dilution that leaves PM, such as PM1 (particles 1 μm or smaller), PM2.5, and PM10 (particles 10 μm or smaller) (Palmisani et al. 2019). The user behavior, power of the device, puffing regimen, device temperature control, wicking ability, and PG/VG ratio have an influence on the amount and type of PM emitted (EL-Hellani et al. 2018; Talih et al. 2015). E-liquids with a higher concentration of PG, a more volatile compound, will release less PM than e-liquids with a higher VG, due to the low volatility of VG (David et al. 2020; Luo et al. 2021). Eversole et al. (2021) demonstrated this using personal aerosol monitors (TSI Model AM510 SidePak, AM510, and AM520 SidePak, TSI Inc., Shoreview, MN) to measure the PM present in ambient air from aerosolized e-liquids with varying PG/VG ratios. The authors showed an increase in PM2.5 levels in the environment after the use of e-liquid with higher VG amounts, indicating that there was a higher risk of PM2.5 secondhand exposure with higher VG composition.
Impact of power level and refill liquid composition on the aerosol output and particle size distribution generated by a new-generation e-cigarette device
Published in Aerosol Science and Technology, 2018
Jérémie Pourchez, Sandrine Parisse, Gwendoline Sarry, Sophie Perinel-Ragey, Jean-Michel Vergnon, Anthony Clotagatide, Nathalie Prévôt
ENDS, in all their shapes and technical designs, have already been present on the market for a decade. Basically, ENDS are battery-powered personal vaporizers. The main components are a mouthpiece, a tank for the refill liquid, a heating element, a battery, and sometimes a microprocessor. The physical principle common to all ENDS is a small heating element that vaporizes a refill liquid to generate an aerosol (called “vape”). This refill liquid (called “e-liquid”) contains nicotine, humectants (such as glycerol and propylene glycol) and in the vast majority of cases, other ingredients in small quantities (water, ethanol, flavorings, etc.) (Breland et al. 2014). Since its emergence in the 2000s and throughout its relatively short history, the ENDS industry has continuously evolved. New technologies were quickly developed, thanks to various innovations and technological breakthroughs. Thus, many products have constantly been brought to market. These rapid developments in manufacturing induce a great variability of ENDS in terms of power source voltage, heating element resistance, and other technical features.
Volatilization and partitioning of residual electronic cigarette emissions to particulate matter
Published in Aerosol Science and Technology, 2023
Henry J. Colby, Erin F. Katz, Peter F. DeCarlo
Electronic cigarettes (e-cigs), a cigarette alternative, allow liquid containing nicotine, flavorings, and more (known as e-liquid), to be inhaled as a gas/aerosol mixture (commonly called vape) by using a high temperature filament for vaporization. This nicotine delivery system is thus significantly different from combustion used for CCs, but much like THS, residue from e-cig vape has been found deposited on surfaces and provides a new avenue for human exposure to the chemicals in e-liquids, including nicotine and nicotine derivatives (Goniewicz and Lee 2015; Khachatoorian et al. 2019; Son et al. 2020). Compared to CCs, these devices have fewer indoor use regulations in the United States (ANRF 2022) which raises concern for the accumulation and aging of potentially hazardous residues associated with frequent indoor use. Some surveys have reported on types of indoor spaces and frequency of e-cig use and indicate that nearly 70% of Spanish e-cig users self-report use in restaurants or bars and 32% use in their workplaces (Matilla-Santander et al. 2017) while in the United States over 50% of employees who observed e-cig use around the workplace reported indoor use (Romberg et al. 2021). Although e-cig vape is understood to provide a much simpler chemical matrix than CC smoke, there remain potential health hazards associated with their use. While various studies have sought to characterize direct emissions of e-cigs (Khlystov and Samburova 2016; Klager et al. 2017; Pankow et al. 2017; Behar et al. 2018; Omaiye et al. 2019), this study is concerned with understanding the ultimate fate of e-cig vape and how surface and gas-phase chemistry results in its uptake to aerosols.