Ground-Based Mobile Measurements to Track Urban Methane Emissions from Natural Gas in 12 Cities across Eight Countries.

To mitigate methane emission from urban natural gas distribution systems, it is crucial to understand local leak rates and occurrence rates. To explore urban methane emissions in cities outside the U.S., where significant emissions were found previously, mobile measurements were performed in 12 cities across eight countries. The surveyed cities range from medium size, like Groningen, NL, to large size, like Toronto, CA, and London, UK. Furthermore, this survey spanned across European regions from Barcelona, ES, to Bucharest, RO. The joint analysis of all data allows us to focus on general emission behavior for cities with different infrastructure and environmental conditions. We find that all cities have a spectrum of small, medium, and large methane sources in their domain. The emission rates found follow a heavy-tailed distribution, and the top 10% of emitters account for 60-80% of total emissions, which implies that strategic repair planning could help reduce emissions quickly. Furthermore, we compare our findings with inventory estimates for urban natural gas-related methane emissions from this sector in Europe. While cities with larger reported emissions were found to generally also have larger observed emissions, we find clear discrepancies between observation-based and inventory-based emission estimates for our 12 cities.

Prospective safety evaluation of automated iomeprol 400 injections for CT through peripheral venous cannulas.

AIM: To evaluate prospectively the safety of contrast medium injection through standard peripheral intravenous cannulas at standard injection sites during clinical routine using iomeprol 400, a contrast agent with high viscosity. MATERIALS AND METHODS: Three thousand, five hundred and fourteen clinical CT examinations undertaken at Saarland University Medical Center were included in this prospective observational trial. The size and site of the cannula as well as the contrast medium injection rate and volume were assessed for each patient. In addition, the ability to aspirate blood though the cannula and the occurrence of complications, such as extravasation or abortion of injection by the automated injector, were recorded. RESULTS: The overall complication rate was 30/3,514 (0.85%). With 22 G cannulas, the complication rate was 8/541 (1.48%) applying flow rates of 1-3.5 ml/s (mean 2.1 ml/s). With 20 G cannulas, complications occurred in 21/2,601 cases (0.81%) with flow rates of 1.5-5 ml/s (mean 3 ml/s). The complication rate using 18 G cannulas was 1/377 (0.26%) for flow rates of 2-6 ml/s (mean 3.5 ml/s). No relationship between the site and size of the cannula to the occurrence of complications was found. The inability to aspirate blood correlated with the development of extravasation. CONCLUSIONS: The injection of contrast agent using standard peripheral venous cannulas is a safe and reliable procedure yielding diagnostic image contrast, even when using highly viscous contrast agents such as iomeprol 400; an aspiration test should be performed before each injection.