A meta-analytic review of microplastic pollution in the Indian Ocean: Ecological health and seafood safety risk implications.

The Indian Ocean (IO) currently bears the second largest plastic load and therefore, has a high potential for microplastic (MP) pollution. Despite the findings from individual studies, the overall MP pollution in the IO is still unclear. Therefore, this meta-analytic review aimed to identify the overall MP contamination state, its ecological health and seafood safety risk implications, and identify future priority areas for MP research in the IO. The data for the occurrence of MPs in seawater, sediment and marine biota in the IO were analysed. Concentrations of MPs in surface water and sediment were in a wide range (surface water: 0.01 to 372,000.00 particles per m3; sediment: 36.80 to 10,600.00 items per kg, respectively) while lower range (0.016 to 10.65 particles per individual) was observed in biota. The meta-analysis indicated that PE was the most abundant polymer type in all three matrices and PE prevalence was higher in sediment. Fibres were the most prevalent MP shape of all three matrices in the IO. The Higher MP accumulation was identified in shrimps (p < 0.05) than the fish species. Results further confirmed that MPs do not magnify along the food chain (p > 0.05). Ecological risk and hazardous effects increased with the presence of polyvinyl chloride (PVC), polyurethane (PUR) and PA due to their high hazardous scores. Overall results indicated that IO is in the high-risk category due to the elevated levels of MP pollution with reference to all three matrices.

Assessment of dispersion of airborne particles of oral/nasal fluid by high flow nasal cannula therapy.

BACKGROUND: Nasal High Flow (NHF) therapy delivers flows of heated humidified gases up to 60 LPM (litres per minute) via a nasal cannula. Particles of oral/nasal fluid released by patients undergoing NHF therapy may pose a cross-infection risk, which is a potential concern for treating COVID-19 patients. METHODS: Liquid particles within the exhaled breath of healthy participants were measured with two protocols: (1) high speed camera imaging and counting exhaled particles under high magnification (6 participants) and (2) measuring the deposition of a chemical marker (riboflavin-5-monophosphate) at a distance of 100 and 500 mm on filter papers through which air was drawn (10 participants). The filter papers were assayed with HPLC. Breathing conditions tested included quiet (resting) breathing and vigorous breathing (which here means nasal snorting, voluntary coughing and voluntary sneezing). Unsupported (natural) breathing and NHF at 30 and 60 LPM were compared. RESULTS: Imaging: During quiet breathing, no particles were recorded with unsupported breathing or 30 LPM NHF (detection limit for single particles 33 µm). Particles were detected from 2 of 6 participants at 60 LPM quiet breathing at approximately 10% of the rate caused by unsupported vigorous breathing. Unsupported vigorous breathing released the greatest numbers of particles. Vigorous breathing with NHF at 60 LPM, released half the number of particles compared to vigorous breathing without NHF.Chemical marker tests: No oral/nasal fluid was detected in quiet breathing without NHF (detection limit 0.28 µL/m3). In quiet breathing with NHF at 60 LPM, small quantities were detected in 4 out of 29 quiet breathing tests, not exceeding 17 µL/m3. Vigorous breathing released 200-1000 times more fluid than the quiet breathing with NHF. The quantities detected in vigorous breathing were similar whether using NHF or not. CONCLUSION: During quiet breathing, 60 LPM NHF therapy may cause oral/nasal fluid to be released as particles, at levels of tens of µL per cubic metre of air. Vigorous breathing (snort, cough or sneeze) releases 200 to 1000 times more oral/nasal fluid than quiet breathing (p < 0.001 with both imaging and chemical marker methods). During vigorous breathing, 60 LPM NHF therapy caused no statistically significant difference in the quantity of oral/nasal fluid released compared to unsupported breathing. NHF use does not increase the risk of dispersing infectious aerosols above the risk of unsupported vigorous breathing. Standard infection prevention and control measures should apply when dealing with a patient who has an acute respiratory infection, independent of which, if any, respiratory support is being used. CLINICAL TRIAL REGISTRATION: ACTRN12614000924651.