Changes in the Chemical Composition of Polyethylene Terephthalate Under UV Radiation in Various Environmental Conditions.

Polyethylene terephthalate has been widely used in the packaging industry. Degraded PET micro-nano plastics could pose public health concerns following release into various environments. This study focuses on PET degradation under ultraviolet radiation using the NIST SPHERE facility at the National Institute of Standards and Technology in saturated humidity (i.e., ≥ 95 % relative humidity) and dry conditions (i.e., ≤ 5 % relative humidity) with varying temperatures (30 °C, 40 °C, and 50 °C) for up 20 days. ATR-FTIR was used to characterize the chemical composition change of degraded PET as a function of UV exposure time. The results showed that the cleavage of the ester bond at peak 1713 cm-1 and the formation of the carboxylic acid at peak 1685 cm-1 are significantly influenced by UV radiation. Furthermore, the formation of carboxylic acid was considerably higher at saturated humidity and 50 °C conditions compared to dry conditions. The ester bond cleavage was also more pronounced in saturated humidity conditions. The novelty of this study is to provide insights into the chemical degradation of PET under environmental conditions, including UV radiation, humidity, and temperature. The results can be used to develop strategies to reduce the environmental impact of plastic pollution.

Mask wearing on an HBCU campus during the COVID-19 pandemic.

Objective: Young adults of age 18-29 years old account for the most COVID-19 cases in the US, and ethnic groups were affected disproportionately. Correctly wearing a face mask remains a critical intervention for COVID-19 mitigation. The study aimed to examine how well Historically Black Colleges and Universities (HBCUs) residents adhered to mask wearing during the pandemic. Methods: We conducted an observational study on an urban HBCU campus and the neighborhoods in Maryland for 13 weeks in spring 2021. Results: Of 1926 (1126 on campus; 800 off campus) persons observed, 89.8% wore masks, with 83.5% covering their mouths and noses. The HBCU campus showed better mask adherence than neighborhoods (92.0% vs. 86.7%). The most common improper mask wearing was nose out, followed by only-on-chin. Cloth and surgical masks were worn the most. Conclusion: The HBCU campus and neighborhood settings presented a high rate of facemask use during the pandemic.