Many types of electronic cigarettes (ECs) are currently in use, but the default flow rate used to simulate puffing is centered on tobacco cigarette flow rates. CORESTA offers several methods and technical guides for evaluation of ECs but there are few puffing topography studies focusing on sub-ohm ECs; differences between real-world usage and that found in the literature appear large. This study focuses on how power and flow rate affect the nicotine yield of a sub-ohm EC. A puffing system (Puff3rd) has been designed and used to produce and collect EC aerosol. Nicotine yield was measured by GC–MS at three power levels and four flow rates. Data analysis was conducted in SAS using the MIXED procedure. Power, flow rate, and their interaction were all significant predictors of nicotine yield. Nicotine yield increased with both the vaping power and the puff flow rate with significant interaction of the two. Findings indicate that using the current CORESTA flow rate (1100 mL/min) to evaluate third-generation ECs underestimates nicotine yield and likely overestimates pyrolysis products. Real users are expected to have 2–3× the nicotine dose measured at 1100 mL/min, which could confound epidemiological studies seeking to link nicotine delivery to product satisfaction and acceptability.

The coronavirus disease 2019 pandemic has imposed unprecedented occupational challenges for healthcare professionals. In dentistry, handheld instruments such as air and electric handpieces, ultrasonic scalers, and air/water syringes are capable of generating aerosols, droplets, and splatter, thereby exposing dental professionals to airborne contaminants such as viruses, bacteria, and fungi. The objective of the present study was to determine the spatial distribution of aerosols by size (0.30 to 20.00 μ m) and the efficacy of a novel aerosol containment device (ACD) in a large operatory room with 12 dental chairs. Real-time portable laser aerosol spectrometers were used to measure the size-resolved number concentration of aerosols generated by a collision nebulizer. Results reported demonstrate that aerosol number concentrations significantly decreased as a function of distance with or without the utilization of the ACD. The ACD was able to efficiently decrease (up to 8.56-fold) the number and size distribution of particles in a large dental clinic. The novel device demonstrated higher efficiency for particles shown to contain the highest levels of severe acute respiratory syndrome coronavirus 2 in Chinese hospitals, thereby showing great promise to potentially decrease the spreading of nosocomial pathogens in dental settings.

Abstract Background There is an increasing range of adverse health effects associated with air pollution at very low concentrations. Few studies have assessed respiratory parameters among filling station attendants. Objectives This study assessed air pollutants; particulate matter (PM10) and total volatile organic compounds (TVOC) concentrations at filling stations as well as determined forced expiratory volume in one second (FEV1) and peak expiratory flow rate (PEFR) levels among filling station attendants. Methods A cross-sectional study was conducted to assess PM10 and TVOC concentrations at 20 systematically selected filling stations in Ibadan North Local Government Area, Ibadan for 2 months using a Thermo Scientific pDR 1500 PM10 monitor and SF2000-TVOC meter. FEV1 and PEFR levels were measured in order to assess the effect of exposure to PM10 and TVOC on lung function of 100 filling station attendants using a PIKO-1 Electronic peakflow/FEV1 meter. Results Total mean PM10 concentrations (μg/m3) in the morning (43.7±16.5) and afternoon (27.8±7.9) were significantly lower (p<0.01) than the World Health Organization (WHO) guideline limit (50 μg/m3). Total mean TVOC concentrations (ppm) in the morning (12.0±3.4) and afternoon (5.6±2.4) were however significantly higher (p<0.01) than the Occupational Safety and Health Administration (OSHA) guideline limit (3 ppm). Mean FEV1 for filling station attendants was 1.63±0.39 and PEFR was 171.7±45.9. Conclusion Filling stations are hotspots for the emission of VOCs and PM10. However, filling station attendants in this study are at risk of exposure to high concentrations of VOCs but not PM10. FEV1 and PEFR values among filling station attendants were very low which could possibly be attributed to extended exposure to air pollutants. Regular medical examinations should also be conducted on filling station attendants in order to aid early detection of deviations in their health status.

Millions of workers are occupationally exposed to volatile organic compounds (VOCs) annually. Current exposure assessment techniques primarily utilize sorbent based preconcentrators to collect VOCs, with analysis performed using chemical or thermal desorption. Chemical desorption typically analyzes 1 µL out of a 1 mL (0.1%) extraction volume providing limited sensitivity. Thermal desorption typically analyzes 100% of the sample which provides maximal sensitivity, but does not allow repeat analysis of the sample and often has greater sensitivity than is needed. In this study we describe a novel photothermal desorption (PTD) technique to bridge the sensitivity gap between chemical desorption and thermal desorption. We used PTD to partially desorb toluene from three carbonaceous substrates; activated carbon powder (AC-p), single-walled carbon nanotube (SWNT) powder (SWNT-p) and SWNT felts (SWNT-f). Sorbents were loaded with 435 ug toluene vapour and irradiated at four light energies. Desorption ranged from <0.007% to 0.86% with a single flash depending on substrate and flash energy. PTD was significantly greater and more consistent in SWNT-f substrates compared to AC-p or SWNT-p at all irradiation energies. We attribute the better performance of SWNT-f to greater utilization of its unique nanomaterials properties: high thermal conductivity along the nanotube axis, and greater interconnection within the felt matrix compared to the powdered form.

12Previous researchers measured the Overall Filtration Efficiency using sodium 13 chloride testing aerosol with aerosol photometer to analyze the reuse of respirators after 14 sterilization. However, this study showed that the Overall Filtration Efficiency would 15 significantly overestimate the respirators' ability to protect against submicrometer 16 particles containing SARS-CoV-2. For example, after three cycle H2O2 vaporous 17 sterilizations, the most penetrating particle size for the N95 level respirators was from 18 250 nm -500 nm, which carried the peak concentration of the SARS-CoV-2 in 19 hospitals. The Size Specific Filtration Efficiency (250 nm -500 nm) dropped to 20 56%±4%, however, the Overall Filtration Efficiency was still 86%±5%. In order to 21 protect health care personnel adequately, we recommend measuring the Size Specific