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3 results on '"number concentrations"'

1. Vertical Profiles of Pollution Particle Concentrations in the Boundary Layer above Paris (France) from the Optical Aerosol Counter LOAC Onboard a Touristic Balloon

Author

Jean-Baptiste Renard, Vincent Michoud, and Jérôme Giacomoni

Subjects
particulate matter, urban pollution, number concentrations, tethered balloon, Chemical technology, TP1-1185
Abstract

Atmospheric pollution by particulate matter represents a significant health risk and needs continuous monitoring by air quality networks that provide mass concentrations for PM10 and PM2.5 (particles with diameter smaller than 10 μm and 2.5 μm, respectively). We present here a new approach to monitor the urban particles content, using six years of aerosols number concentration measurements for particles in the 0.2−50 μm size range. These measurements are performed by the Light Optical Aerosols Counter (LOAC) instrument onboard the tethered touristic balloon “Ballon de Paris Generali”, in Paris, France. Such measurements have allowed us first to detect at ground a seasonal variability in the particulate matter content, due to the origin of the particles (anthropogenic pollution, pollens), and secondly, to retrieve the mean evolution of particles concentrations with height above ground up to 150 m. Measurements were also conducted up to 300 m above ground during major pollution events. The vertical evolution of concentrations varies from one event to another, depending on the origin of the pollution and on the meteorological conditions. These measurements have shown the interest of performing particle number concentrations measurements for the air pollution monitoring in complement with regulatory mass concentrations measurement, to better evaluate the intensity of the pollution event and to better consider the effect of smallest particles, which are more dangerous for human health.

Published
2020
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2. Modeling of the Concentrations of Ultrafine Particles in the Plumes of Ships in the Vicinity of Major Harbors

Author

Martin Otto Paul Ramacher, Matthias Karl, Jukka-Pekka Jalkanen, Liisa Pirjola, Ari Karppinen, Jaakko Kukkonen, and Department of Physics

Subjects
010504 meteorology & atmospheric sciences, Health, Toxicology and Mutagenesis, NUMBER CONCENTRATIONS, lcsh:Medicine, 010501 environmental sciences, Atmospheric sciences, 01 natural sciences, 114 Physical sciences, Article, ORGANIC VAPORS, chemistry.chemical_compound, ACID-WATER NUCLEATION, SULFURIC-ACID, shipping emissions, Ultrafine particle, HEAVY-DUTY, Cities, Sulfate, OXIDATIVE STRESS, Scavenging, Air quality index, Finland, Ships, 0105 earth and related environmental sciences, Air Pollutants, particle number concentration, SIZE DISTRIBUTIONS, PARTICULATE AIR-POLLUTION, lcsh:R, Public Health, Environmental and Occupational Health, population exposure, Models, Theoretical, Atmospheric dispersion modeling, air quality, 3142 Public health care science, environmental and occupational health, atmospheric nucleation, Aerosol, Plume, ultrafine particles, aerosol dynamics modeling, chemistry, EXHAUST EMISSIONS, 13. Climate action, fuel sulfur content, Environmental science, Particulate Matter, Dispersion (chemistry), Environmental Monitoring
Abstract

Marine traffic in harbors can be responsible for significant atmospheric concentrations of ultrafine particles (UFPs), which have widely recognized negative effects on human health. It is therefore essential to model and measure the time evolution of the number size distributions and chemical composition of UFPs in ship exhaust to assess the resulting exposure in the vicinity of shipping routes. In this study, a sequential modelling chain was developed and applied, in combination with the data measured and collected in major harbor areas in the cities of Helsinki and Turku in Finland, during winter and summer in 2010&ndash, 2011. The models described ship emissions, atmospheric dispersion, and aerosol dynamics, complemented with a time&ndash, microenvironment&ndash, activity model to estimate the short-term UFP exposure. We estimated the dilution ratio during the initial fast expansion of the exhaust plume to be approximately equal to eight. This dispersion regime resulted in a fully formed nucleation mode (denoted as Nuc2). Different selected modelling assumptions about the chemical composition of Nuc2 did not have an effect on the formation of nucleation mode particles. Aerosol model simulations of the dispersing ship plume also revealed a partially formed nucleation mode (Nuc1, peaking at 1.5 nm), consisting of freshly nucleated sulfate particles and condensed organics that were produced within the first few seconds. However, subsequent growth of the new particles was limited, due to efficient scavenging by the larger particles originating from the ship exhaust. The transport of UFPs downwind of the ship track increased the hourly mean UFP concentrations in the neighboring residential areas by a factor of two or more up to a distance of 3600 m, compared with the corresponding UFP concentrations in the urban background. The substantially increased UFP concentrations due to ship traffic significantly affected the daily mean exposures in residential areas located in the vicinity of the harbors.

Published
2020

3. Urban Aerosol Particle Size Characterization in Eastern Mediterranean Conditions

Author

Lubna Dada, Simo Hakala, Tareq Hussein, Markku Kulmala, Tuukka Petäjä, Air quality research group, Department of Physics, Institute for Atmospheric and Earth System Research (INAR), and INAR Physics

Subjects
CHARACTERIZING MINERAL DUSTS, Atmospheric Science, Materials science, 010504 meteorology & atmospheric sciences, Particle number, BACKGROUND ATMOSPHERE, NUMBER CONCENTRATIONS, 010501 environmental sciences, Environmental Science (miscellaneous), Atmospheric sciences, 114 Physical sciences, 01 natural sciences, Wind speed, PARTICULATE MATTER, Ultrafine particle, Relative humidity, diurnal, COASTAL CITY JEDDAH, modal structure, 0105 earth and related environmental sciences, ULTRAFINE PARTICLES, particle number size distribution, coarse, meteorological effect, AIR-POLLUTION, seasonal, Aerosol, 13. Climate action, submicron, BLACK CARBON, Particle, Particle size, Geometric mean, PHYSICAL-CHARACTERISTICS, TRANSPORT MICROENVIRONMENTS
Abstract

Characterization of urban particle number size distribution (PNSD) has been rarely reported/performed in the Middle East. Therefore, we aimed at characterizing the PNSD (0.01&ndash, 10 &micro, m) in Amman as an example for an urban Middle Eastern environment. The daily mean submicron particle number concentration (PNSub) was 6.5 &times, 103&ndash, 7.7 &times, 104 cm&minus, 3 and the monthly mean coarse mode particle number concentration (PNCoarse) was 0.9&ndash, 3.8 cm&minus, 3 and both had distinguished seasonal variation. The PNSub also had a clear diurnal and weekly cycle with higher concentrations on workdays (Sunday&ndash, Thursday, over 3.3 &times, 3) than on weekends (below 2.7 &times, 3). The PNSub constitute of 93% ultrafine fraction (diameter &lt, 100 nm). The mean particle number size distributions was characterized with four well-separated submicron modes (Dpg,I, Ni): nucleation (22 nm, 9.4 &times, 103 cm&minus, 3), Aitken (62 nm, 3.9 &times, 3), accumulation (225 nm, 158 cm&minus, 3), and coarse (2.23 &micro, m, 1.2 cm&minus, 3) in addition to a mode with small geometric mean diameter (GMD) that represented the early stage of new particle formation (NPF) events. The wind speed and temperature had major impacts on the concentrations. The PNCoarse had a U-shape with respect to wind speed and PNSub decreased with wind speed. The effect of temperature and relative humidity was complex and require further investigations.

Published
2019

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