Found 9746 publications. Showing page 345 of 390:
2010
The increased availability of commercially-available low-cost air quality sensors combined with increased interest in their use by citizen scientists, community groups, and professionals is resulting in rapid adoption, despite data quality concerns. We have characterized three out-the-box PM sensor systems under different environmental conditions, using field colocation against reference equipment. The sensor systems integrate Plantower 5003, Sensirion SPS30 and Alphasense OCP-N3 PM sensors. The first two use photometry as a measuring technique, while the third one is an optical particle counter. For the performance evaluation, we co-located 3 units of each manufacturer and compared the results against optical (FIDAS) and gravimetric (KFG) methods for a period of 7 weeks (28 August to 19 October 2020). During the period from 2nd and 5th October, unusually high PM concentrations were observed due to a long-range transport episode. The results show that the highest correlations between the sensor systems and the optical reference are observed for PM1, with coefficients of determination above 0.9, followed by PM2.5. All the sensor units struggle to correctly measure PM10, and the coefficients of determination vary between 0.45 and 0.64. This behavior is also corroborated when using the gravimetric method, where correlations are significantly higher for PM2.5 than for PM10, especially for the sensor systems based on photometry. During the long range transport event the performance of the photometric sensors was heavily affected, and PM10 was largely underestimated. The sensor systems evaluated in this study had good agreement with the reference instrumentation for PM1 and PM2.5; however, they struggled to correctly measure PM10. The sensors also showed a decrease in accuracy when the ambient size distribution was different from the one for which the manufacturer had calibrated the sensor, and during weather conditions with high relative humidity. When interpreting and communicating air quality data measured using low-cost sensor systems, it is important to consider such limitations in order not to risk misinterpretation of the resulting data.
MDPI
2021
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Assessment of heavy metal transboundary pollution, progress in model development and mercury research. EMEP Status Report, 2/2016
2016
Assessment of heavy metal transboundary pollution on regional and national scales, transition to the new EMEP grid. EMEP Status Report, 2/2017
2017
Assessment of heavy metal transboundary pollution on global, regional and national scales
Meteorological Synthesizing Centre - East (MSC-E)
2018
2009
Assessment of heavy metal and POP pollution on global, regional and national scales
Meteorological Synthesizing Centre - East (MSC-E)
2022
Assessment of ground-level ozone in EEA member countries, with a focus on long-term trends. Technical report, 7/2009
2009
Assessment of governmental air management systems. Abu Dhabi Air Monitoring Network Supervision. NILU OR
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2014
Assessment of emissions/ discharges of mercury reaching the Arctic environment. NILU OR
Our knowledge of mercury fluxes on a global scale is still incomplete. The above presented estimates for Europe and North America seem to contribute less about 25 % to the global anthropogenic emissions of the element to the atmosphere. The majority of the remaining emissions originate from combustion of fossil fuels, particularly in the Asian countries including China, India, and South and North Korea. Even less and very controversial information is available on emissions of mercury from natural sources, including volatilization of the element from terrestrial and aquatic surfaces. In general, it is assumed that natural emissions of the element are about 3000 t/year, thus contributing more 60 % to the total global emissions of mercury. However, much work needs to be done in order to verify the above estimate.
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