Exposure to respiratory droplets contributes greatly to the spread of SARS-CoV-2 virus during the COVID-19 pandemic. This study investigates the effectiveness of various face coverings to reduce cough-generated airborne particle concentrations at 0.3, 0.9, and 1.8 m away from the source in an indoor environment. We measured the particle number concentration (PNC) and particle size distribution under seven different conditions: (1) no face covering; (2) face shield only; (3) cloth mask; (4) face shield + cloth mask; (5) surgical mask; (6) face shield + surgical mask; (7) N95 respirator or equivalent (i.e., KN95 mask). We observed significant increases in PNCs at 0.3 m under conditions #1-4 and a trend toward an increase at 1.8 m, compared to the background. The face shield by itself provided little protection with a particle reduction of 4 ± 23% relative to no face covering, while the cloth masks reduced the particles by 77 ± 7%. Surgical and N95/KN95 masks performed well and substantially reduced the cough droplets to ≤ 6% at 0.3 m. In this study, most cough-generated particles were found less than 2.5 µm with an average mode diameter of ~ 0.6 µm at 0.3 m. Approximately 80% of the particles ≤ 2.5 µm were able to travel to 0.9 m, and 10% of the particles ≤ 1.1 µm likely reached 1.8 m. Based on these results, face coverings, especially surgical and N95/KN95 masks, should be recommended as effective preventive measures to reduce outward transport of respiratory droplets during the COVID-19 pandemic.

With the rapid increase in electronic cigarette (e-cig) users worldwide, secondhand exposure to e-cig aerosols has become a serious public health concern. We summarize the evidence on the effects of e-cigs on indoor air quality, chemical compositions of mainstream and secondhand e-cig aerosols, and associated respiratory and cardiovascular effects. The use of e-cigs in indoor environments leads to high levels of fine and ultrafine particles similar to tobacco cigarettes (t-cigs). Concentrations of chemical compounds in e-cig aerosols are generally lower than those in t-cig smoke, but a substantial amount of vaporized propylene glycol, vegetable glycerin, nicotine, and toxic substances, such as aldehydes and heavy metals, has been reported. Exposures to mainstream e-cig aerosols have biologic effects but only limited evidence shows adverse respiratory and cardiovascular effects in humans. Long-term studies are needed to better understand the dosimetry and health effects of exposures to secondhand e-cig aerosols.

An electronic cigarette (e-cig) generates aerosols by vaporizing the e-liquid, which mainly consists of propylene glycol (PG), vegetable glycerin (VG), and nicotine. Understanding the effects of e-liquid main compositions on e-cig aerosols is important for exposure assessment. This study investigated how the PG/VG ratio and nicotine content affect e-cig aerosol emissions and dynamics. A tank-based e-cig device with 10 different flavorless e-liquid mixtures (e.g., PG/VG ratios of 0/100, 10/90, 30/70, 50/50, and 100/0 with 0.0% or 2.4% nicotine) was used to puff aerosols into a 0.46 m 3 stainless steel chamber for 0.5 h. Real-time measurements of particle number concentration (PNC), fine particulate matter (PM 2.5 ), and particle size distributions were conducted continuously throughout the puffing and the following 2-h decay period. During the decay period, particle loss rates were determined by a first-order log-linear regression and used to calculate the emission factor. The addition of nicotine in the e-liquid significantly decreased the particle number emission factor by 33%. The PM 2.5 emission factor significantly decreased with greater PG content in the e-liquid. For nicotine-free e-liquids, increasing the PG/VG ratio resulted in increased particle loss rates measured by PNC and PM 2.5 . This pattern was not observed with nicotine in the e-liquids. The particle loss rates, however, were significantly different with and without nicotine especially when the PG/VG ratios were greater than 30/70. Compared with nonvolatile diethyl-hexyl subacute (DEHS) aerosols, e-cig particle concentration decayed faster inside the chamber, presumably due to evaporation. These results have potential implications for assessing human exposure to e-cig aerosols.

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Optimizing process parameters that affect the remediation time and power consumption can improve the treatment efficiency of the electrokinetic remediation as well as determine the cost of a remediation action. Lab-scale electrokinetic remediation of Pb-contaminated soils was investigated for the effect of complexant ethylenediaminetetraacetic acid (EDTA) and acetic acid and approaching anode on the removal efficiency of Pb. When EDTA was added to the catholyte, EDTA dissolved insoluble Pb in soils to form soluble Pb-EDTA complexes, increasing Pb mobility and accordingly removal efficiency. The removal efficiency was enhanced from 47.8 to 61.5 % when the EDTA concentration was increased from 0.1 to 0.2 M, showing that EDTA played an important role in remediation. And the migration rate of Pb was increased to 72.3 % when both EDTA and acetic acid were used in the catholyte. The "approaching anode electrokinetic remediation" process in the presence of both EDTA and acetic acid had a higher Pb-removal efficiency with an average efficiency of 83.8 %. The efficiency of electrokinetic remediation was closely related to Pb speciation. Exchangeable and carbonate-bounded Pb were likely the forms which could be removed. All results indicate that the approaching anode method in the presence of EDTA and acetic acid is an advisable choice for electrokinetic remediation of Pb-contaminated soil.

Antihistamines, especially H1 antihistamines, are widely used in the treatment of allergic diseases such as urticaria and allergic rhinitis, mainly for reversing elevated histamine and anti‐allergic effects. Antihistamines are generally safe, but some patients experience adverse reactions, such as cardiotoxicity, central inhibition and anticholinergic effects. There are also individual differences in antihistamine efficacy in clinical practice. The concept of individualized medicine has been deeply rooted in people's minds since it was put forward. Pharmacogenomics is the study of the role of inheritance in individual variations in drug response. In recent decades, pharmacogenomics has been developing rapidly, which provides new ideas for individualized medicine. Polymorphisms in the genes encoding metabolic enzymes, transporters and target receptors have been shown to affect the efficacy of antihistamines. In addition, recent evidence suggests that gene polymorphisms influence urticaria susceptibility and antihistamine therapy. Here, we summarize current reports in this area, aiming to contribute to future research in antihistamines and clinical guidance for antihistamines use in individualized medicine.

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