Measurement of heating coil temperature for e-cigarettes with a "top-coil" clearomizer.

OBJECTIVES: To determine the effect of applied power settings, coil wetness conditions, and e-liquid compositions on the coil heating temperature for e-cigarettes with a "top-coil" clearomizer, and to make associations of coil conditions with emission of toxic carbonyl compounds by combining results herein with the literature. METHODS: The coil temperature of a second generation e-cigarette was measured at various applied power levels, coil conditions, and e-liquid compositions, including (1) measurements by thermocouple at three e-liquid fill levels (dry, wet-through-wick, and full-wet), three coil resistances (low, standard, and high), and four voltage settings (3-6 V) for multiple coils using propylene glycol (PG) as a test liquid; (2) measurements by thermocouple at additional degrees of coil wetness for a high resistance coil using PG; and (3) measurements by both thermocouple and infrared (IR) camera for high resistance coils using PG alone and a 1:1 (wt/wt) mixture of PG and glycerol (PG/GL). RESULTS: For single point thermocouple measurements with PG, coil temperatures ranged from 322 ‒ 1008°C, 145 ‒ 334°C, and 110 ‒ 185°C under dry, wet-through-wick, and full-wet conditions, respectively, for the total of 13 replaceable coil heads. For conditions measured with both a thermocouple and an IR camera, all thermocouple measurements were between the minimum and maximum across-coil IR camera measurements and equal to 74% ‒ 115% of the across-coil mean, depending on test conditions. The IR camera showed details of the non-uniform temperature distribution across heating coils. The large temperature variations under wet-through-wick conditions may explain the large variations in formaldehyde formation rate reported in the literature for such "top-coil" clearomizers. CONCLUSIONS: This study established a simple and straight-forward protocol to systematically measure e-cigarette coil heating temperature under dry, wet-through-wick, and full-wet conditions. In addition to applied power, the composition of e-liquid, and the devices' ability to efficiently deliver e-liquid to the heating coil are important product design factors effecting coil operating temperature. Precautionary temperature checks on e-cigarettes under manufacturer-recommended normal use conditions may help to reduce the health risks from exposure to toxic carbonyl emissions associated with coil overheating.

The Surface Tension of Synthetic Blood used for ASTM F1670 Penetration Tests.

The American Society for Testing and Material (ASTM International) F1670 test method was based on research involving transmission of bloodborne pathogens (Hepatitis B, Hepatitis C, and HIV) in the 1980s. The test method details the measurement of synthetic blood penetration through garments. A key parameter affecting penetration is synthetic blood surface tension which is measured via du Noüy ring tensiometer. However, little is known about the sources of variation impacting surface tension measurements. In this study, the synthetic blood used for ASTM F1670 was evaluated from within the ASTM F903 test apparatus and with two mixing treatments. Measurements were compared against two outside laboratories and with two alternate tensiometric methods (pendant drop and capillary rise). It was found that using the methods specified in the ASTM F1670 test method, surface tension of the synthetic blood was not 40-44 dynes/cm as was expected. The surface tension was initially above 50 dynes/cm and declined to below 40 dynes/cm after 60 minutes. The surface tension within the penetration cell was relatively constant over time, showing that the surface tension measurements outside the penetration cell are not indicative of the surface tension within the apparatus during the test. Shaking the synthetic blood, a mixing procedure detailed in the ASTM F1670 test method, increased the surface tension. The increase was greatest in a container having more airspace. Du Noüy ring measurements by NIOSH compared to external labs were within 15%. Testing with alternate methods showed that the "open-to-atmosphere" methods (ring and drop) began lower and declined rapidly when compared to the "closed-to-atmosphere" method (capillary). Results of this research will help amend the ASTM F1670 standard to better characterize the measurement and handling of synthetic blood used in the ASTM F1670 test and to provide a framework for consideration of test fluid used in future ASTM standards.

Evaluation of a passive method for determining particle penetration through protective clothing materials.

The risk of workers' exposure to aerosolized particles has increased with the upsurge in the production of engineered nanomaterials. Currently, a whole-body standard test method for measuring particle penetration through protective clothing ensembles is not available. Those available for respirators neglect the most common challenges to ensembles, because they use active vacuum-based filtration, designed to simulate breathing, rather than the positive forces of wind experienced by workers. Thus, a passive method that measures wind-driven particle penetration through ensemble fabric has been developed and evaluated. The apparatus includes a multidomain magnetic passive aerosol sampler housed in a shrouded penetration cell. Performance evaluation was conducted in a recirculation aerosol wind tunnel using paramagnetic Fe3O4 (i.e., iron (II, III) oxide) particles for the challenge aerosol. The particles were collected on a PVC substrate and quantified using a computer-controlled scanning electron microscope. Particle penetration levels were determined by taking the ratio of the particle number collected on the substrate with a fabric (sample) to that without a fabric (control). Results for each fabric obtained by this passive method were compared to previous results from an automated vacuum-based active fractional efficiency tester (TSI 3160), which used sodium chloride particles as the challenge aerosol. Four nonwoven fabrics with a range of thicknesses, porosities, and air permeabilities were evaluated. Smoke tests and flow modeling showed the passive sampler shroud provided smooth (non-turbulent) air flow along the exterior of the sampler, such that disturbance of flow stream lines and distortion of the particle size distribution were reduced. Differences between the active and passive approaches were as high as 5.5-fold for the fabric with the lowest air permeability (0.00067 m/sec-Pa), suggesting the active method overestimated penetration in dense fabrics because the active method draws air at a constant flow rate regardless of the resistance of the test fabric. The passive method indicated greater sensitivity since penetration decreased in response to the increase in permeability.

Evaluation of gowns and coveralls used by medical personnel working with Ebola patients against simulated bodily fluids using an Elbow Lean Test.

Gowns and coveralls are important components of protective ensembles used during the management of known or suspected Ebola patients. In this study, an Elbow Lean Test was used to obtain a visual semi-quantitative measure of the resistance of medical protective garments to the penetration of two bodily fluid simulants. Tests were done on swatches of continuous and discontinuous regions of fabrics cut from five gowns and four coveralls at multiple elbow pressure levels (2-44 PSI). Swatches cut from the continuous regions of one gown and two coveralls did not have any strike-through. For discontinuous regions, only the same gown consistently resisted fluid strike-through. As hypothesized, with the exception of one garment, fluid strike-through increased with higher applied elbow pressure, was higher for lower fluid surface tension, and was higher for the discontinuous regions of the protective garments.

A recirculation aerosol wind tunnel for evaluating aerosol samplers and measuring particle penetration through protective clothing materials.

A recirculation aerosol wind tunnel was designed to maintain a uniform airflow and stable aerosol size distribution for evaluating aerosol sampler performance and determining particle penetration through protective clothing materials. The oval-shaped wind tunnel was designed to be small enough to fit onto a lab bench, have optimized dimensions for uniformity in wind speed and particle size distributions, sufficient mixing for even distribution of particles, and minimum particle losses. Performance evaluation demonstrates a relatively high level of spatial uniformity, with a coefficient of variation of 1.5-6.2% for wind velocities between 0.4 and 2.8 m s(-1) and, in this range, 0.8-8.5% for particles between 50 and 450 nm. Aerosol concentration stabilized within the first 5-20 min with, approximately, a count median diameter of 135 nm and geometric standard deviation of 2.20. Negligible agglomerate growth and particle loss are suggested. The recirculation design appears to result in unique features as needed for our research.

Evaluation of nano- and submicron particle penetration through ten nonwoven fabrics using a wind-driven approach.

Existing face mask and respirator test methods draw particles through materials under vacuum to measure particle penetration. However, these filtration-based methods may not simulate conditions under which protective clothing operates in the workplace, where airborne particles are primarily driven by wind and other factors instead of being limited to a downstream vacuum. This study was focused on the design and characterization of a method simulating typical wind-driven conditions for evaluating the performance of materials used in the construction of protective clothing. Ten nonwoven fabrics were selected, and physical properties including fiber diameter, fabric thickness, air permeability, porosity, pore volume, and pore size were determined. Each fabric was sealed flat across the wide opening of a cone-shaped penetration cell that was then housed in a recirculation aerosol wind tunnel. The flow rate naturally driven by wind through the fabric was measured, and the sampling flow rate of the Scanning Mobility Particle Sizer used to measure the downstream particle size distribution and concentrations was then adjusted to minimize filtration effects. Particle penetration levels were measured under different face velocities by the wind-driven method and compared with a filtration-based method using the TSI 3160 automated filter tester. The experimental results show that particle penetration increased with increasing face velocity, and penetration also increased with increasing particle size up to about 300 to 500 nm. Penetrations measured by the wind-driven method were lower than those obtained with the filtration method for most of the fabrics selected, and the relative penetration performances of the fabrics were very different due to the vastly different pore structures.

Resuspension of indoor aeroallergens and relationship to lung inflammation in asthmatic children.

Studies have shown links between the concentration of allergens found in homes and asthma. Inhalation of allergens present in settled residential dust can occur when the dust is resuspended via human activity or air currents. Although previous studies have measured allergen concentrations in homes, the focus has been on the presence of the allergens in settled dust samples. However, the actual inhalation exposure is to airborne allergens. The relationship between the settled dust composition and suspended allergens and endotoxin and the effect of exposure of these aeroallergens to asthmatics are not well understood for species typically present indoors. In this study, settled dust and airborne particulate matter samples were collected in the homes and school classrooms of asthmatic children of ages 9 to 16 and analyzed for endotoxin and allergens including dust mite and cockroach allergen, and dog and cat dander (Der p1, Der f1, Bla g1, Can f1, and Fel d1, respectively). Concentrations of cockroach allergen were below detection limit for all samples. Measurements of the settled dust samples show higher dust mite allergen in bedroom samples than in living room samples. Concentrations of airborne endotoxin and indoor allergens were generally higher in the homes than those measured at school. Within the homes, higher concentrations of airborne allergens and endotoxin were observed in the living rooms compared to the bedrooms. Resuspension rates for endotoxin, dust mite allergen, and, cat and dog dander were estimated in this study. Calculated resuspension rates for cat dander (8.1x10(-7)+/-3.5x10(-7)min(-1)) and dust mite allergen (2.1x10(-6)+/-7.6x10(-7)min(-1)and 1.4x10(-5)+/-4.6x10(-6)min(-1) for Der p 1 and Der f 1, respectively) were found to be higher than those for dog dander (3.1x10(-7)+/-1.3x10(-7)min(-1)) and endotoxin (3.6x10(-7)+/-1.6x10(-7)min(-1)). Markers of asthma inflammation including nitrate in exhaled breath condensate (EBC) and exhaled nitric oxide (eNO), were correlated with the concentrations of dust mite allergen (Der p 1) (Spearman r=0.598; p-value=0.068 for EBC and Spearman r=0.819; p-value=0.007 for eNO) and cat dander (Fel d 1) (Spearman r=0.917; p-value=0.0002 for EBC and Spearman r=0.697; p-value=0.054 for eNO) present in PM(10) samples.

Factor analysis of submicron particle size distributions near a major United States-Canada trade bridge.

A factor analytic model has been applied to resolve and apportion particles based on submicron particle size distributions downwind of a United States-Canada bridge in Buffalo, NY. The sites chosen for this study were located at gradually increasing distances downwind of the bridge complex. Seven independent factors were resolved, including four factors that were common to all of the five sites considered. The common factors were generally characterized by the existence of two or more number and surface area modes. The seven factors resolved were identified as follows: fresh tail-pipe diesel exhaust, local/street diesel traffic, aged/evolved diesel particles, spark-ignition gasoline emissions, background urban emissions, heavy-duty diesel agglomerates, and secondary/transported material. Submicron (<0.5 microm) and ultrafine (<0.1 microm) particle emissions downwind of the bridge were dominated by commercial diesel truck emissions. Thus, this study obtained size distinction between fresh versus aged vehicle exhaust and spark-ignition versus diesel emissions based on the measured high time-resolution particle number concentrations. Because this study mainly used particles <300 nm in diameter, some sources that would usually exhibit number modes >100 nm were not resolved. Also, the resolved profiles suggested that the major number mode for fresh tailpipe diesel exhaust might exist below the detection limit of the spectrometer used. The average particle number contributions from the resolved factors were highest closest to the bridge.

Effects of select PM-associated metals on alveolar macrophage phosphorylated ERK1 and -2 and iNOS expression during ongoing alteration in iron homeostasis.

It was hypothesized that relative mass relationships among select constituent metals and iron (Fe3+) govern the pulmonary immunotoxic potential of any PM(2.5) sample, as these determine the extent to which Fe3+ binding by transferrin is affected (resulting in altered alveolar macrophage [AM] Fe status and subsequent antibacterial function). Iron response protein (IRP) binding activity is a useful indirect measurement of changes in Fe status, as reductions in cell Fe levels lead to increases in IRP binding. However, AM IRP activity can be affected by an increased presence of nitric oxide generated by inducible nitric oxide synthase (iNOS). This study sought to determine if any changes in AM IRP activity induced by PM(2.5) constituents V, Mn, or Al were independent from effects of the metals on cell NO formation. NR8383 rat AM were exposed to Fe3+ alone or combined with V, Mn, or Al at metal:Fe ratios representative of those in PM(2.5) collected in New York City, Los Angeles, and Seattle during fall 2001. Cells were then assessed for changes in IRP activity and iNOS expression. Phosphorylated extracellular signal-regulated kinase (ERK) 1 and 2 levels were also measured since activated ERKs are involved in signaling pathways that lead to increased iNOS expression. The results indicate that V and Al, and to a lesser extent Mn, altered IRP activity, though the effects were not consistently concentration dependent. Furthermore, while V and Mn treatments did not induce iNOS expression, Al did. These results confirmed our hypothesis that certain metals associated with PM(2.5) might alter the pulmonary immunocompetence of exposed hosts by affecting the Fe status of AM, a major class of deep lung defense cells.

Total lung deposition of ultrafine particles in elderly subjects during controlled breathing.

Ultrafine particulate matter (PM) in the air may be harmful to health, particularly in elderly subjects. From the dosimetry point of view, it is not known if the elderly subjects are more susceptible to exposure to ultrafine PM. We measured the total deposition fraction (TDF) of ultrafine PM (NMD = 0.04-0.1 microm in number median diameter) in the lungs of healthy, elderly subjects (age = 69 +/- 5 yr) and compared the results with those obtained from young adults (age = 31 +/- 4 yr) in an earlier study. Subjects inhaled the aerosols with six different breathing patterns: three different tidal volumes (V(t) = 500, 750, and 1000 ml) and two flow rates (Q) for each V(t). TDF was measured breath by breath in situ by measuring aerosol concentrations on inhalation and exhalation using an ultrafine condensation particle counter. Mean TDF (+/-SD) of the elderly subjects was 0.43 +/- 0.03, 0.36 +/- 0.04, 0.31 +/- 0.03, and 0.27 +/- 0.02 for NMD = 0.04, 0.06, 0.08, and 0.1 microm, respectively, for V(t) = 500 ml and Q = 250 ml/s. These and all other results were very similar to those of young adults. The results suggest that healthy, elderly subjects are not subjected to a greater respiratory dose of ultrafine PM than young adults under the same exposure conditions.