We present the results of a multi-season field evaluation of a low-cost optical particle counting sensor (Purple Air PA-II) that reports mass concentration of particulate matter with diameter less than 2.5 microns (PM2.5), and is part of a relatively large and growing network of microelectronic internet-of-things sensors. We assessed 16 months of PA-II PM2.5 data collected in a near-road urban setting in the humid climate of Charlotte, North Carolina. The PA-II was collocated with a Federal Equivalent Method Beta Attenuation Monitor (BAM model 1022), and with a weather station that monitored ambient relative humidity (RH) and temperature (T). We tested and used a multiple linear regression model with BAM PM2.5, RH, and T as predictors to model the reported PA-II PM2.5. The results show a 27-57% improvement in the accuracy of the PA-II PM2.5 data relative to the reference data from the BAM, with the highest percentage improvements for moderate to high RH. The methodologies in our study are broadly applicable to other field studies of low-cost monitors, and the results are a critical improvement that suggest that PA-II may indeed be suitable for air quality, health, and urban aerosol research.

The coronavirus 2019 (COVID-19) outbreak in March led Davidson College to move from face-to-face classes and laboratories to mostly synchronous Zoom meetings. Prior to COVID-19, the majority of our faculty and students had little experience with remote instruction. With only 5 days to develop a plan, we revisited our individual and department learning goals and worked collectively to help each other redesign and redeploy our courses. In this reflective piece, we provide examples of how each member of our department collaborated with our students to ensure a relatively smooth transition to remote teaching across our entire curriculum while maintaining inclusive excellence. Specific strategies for adapting class meetings, assignments, assessments, additional support, and labs are provided along with select examples. Common themes across the curriculum included increased flexibility, the desire to maintain community, and the need for additional academic, technical, and emotional support. We hope our reflections will be helpful to our chemistry colleagues as we move into the uncertainty of the fall semester.

IntroductionWaterpipe tobacco smoking continues to show increasing popularity, especially among individuals between 18 and 22 years old. Waterpipe tobacco smoke (WTS) is a mixture of particulates and gases formed from the combustion of the charcoal and volatilisation and humidification of the tobacco+humectant+flavouring substrate known as shisha or mu’assel. As such, variation in the configuration of the waterpipe may affect the particles produced. Our study focuses on the effects of waterpipe size on the physical properties and cytotoxicity of the smoke produced.MethodsShisha type and headspace volume were held constant and a modified Beirut puff protocol was followed while the size of the waterpipe was varied. Particle concentrations and size distributions were measured using a TSI Engine Exhaust Particle Sizer. Type II alveolar cells were exposed to smoke at the air-liquid interface and two metrics of cell health analysed.ResultsIn a 30 min session, we observed a decrease in total particle concentration (1014–1013) and mass (10 000–2800 mg/m3) and an increase in particle size (125–170 nm) as pipe height increases from 22 to 55 cm and bowl size from 300 to 1250 mL. Smoke from all pipe sizes caused decreases in lysosomal function (>40%) and membrane integrity (>60%) 24 hours post 57 min exposure, and meet the National Institutes of Health definition of a cytotoxic agent (≥30% decrease in cell viability).ConclusionSmoke from waterpipes of all sizes causes significant alveolar cellular harm, indicating that this device needs regulation as a hazard to human health.

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