Traffic particles

Maynard D, Coull BA, Gryparis A et al (2007) Mortality risk associated with short-term exposure to traffic particles and sulfates. Environ Health Perspect 115 751-755 McDonald JD, Harrod KS, Seagrave J et al (2004) Effects of low sulfur fuel and a catalyzed particle trap on the composition and toxicity of diesel emissions. Environ Health Perspect 112 1307-1312... 

In densely populated areas, traffic is responsible for massive exhausts of nitrous oxides, soot, polyaromatic hydrocarbons, and carbon monoxide. Traffic emissions also markedly contribute to the formation of ozone in the lower parts of the atmosphere. In large cities, fine particle exposure causes excess mortality which varies between one and five percent in the general population. Contamination of the ground water reservoirs with organic solvents has caused concern in many countries due to the persistent nature of the pollution. A total exposure assessment that takes into consideration all exposures via all routes is a relatively new concept, the significance of which is rapidly increasing. 

Studies of atmospheric particles show that their distribution is often birno-dal i.e., the particles are made up of rwo separate fractions, one with fine and one with coarse particles (Fig. 9.1). The coarse particles, from about 2.5 pm upward, are made up of natural dust from the effect of wind, erosion, plants, volcanoes, etc. The finer fraction is made up of particles smaller than 2.5 pm and consists primarily of particles from human activity, combustion, traffic, and processes. 

Total number of particle operator, 541 Traffic dynamics, 263 Traffic flow problem, 252,263 Trajectory, closed, 328 Transformation theory of quantum mechanics, 409... 

The rooms without aerosol sources and low ventilation rate (v<0.3 hf1 ) had low aerosol concentrations (2 103 - 104 cm-3) due to the small influence of the higher aerosol concentrations outdoors (aerosols by traffic and combustions) (Table la). In this case the aerosol in the room air was aged by coagulation and plateout and had less condensation nuclei of smaller sizes (d<100 nm). Rooms with a moderate ventilation show higher particle concentrations ((1-5) 10 cm 3) (Table Ila). With aerosol sources in a room (Table III) the aerosol concentrations can increase to 5 105 particles/cm3. The relative error of the measured particle concentration is in the order of 15% primary determined by the uncertainties of the absolute calibrations of the condensation nuclei counter. 

Salts of agents have negligible vapor pressure and will not evaporate. Depending on the size of the individual particles and on any encapsulation or coatings applied to the particles, they can be reaerosolized by ground traffic or strong winds. 

From Smith and Harrison (1996). Sampler elevation 15 m, situated 300 ni from a high traffic spine roadway. Particle phase collected on Teflon membrane filter (TMF) gas-phase species trapped downstream on PUF plugs. Daily 24-h samples collected during February 1992 mean TSP during that period 60 /j.g m-3. 

Moller, M., I. Alfheim, S. Larssen, and A. Mikalsen, Muagenicity of Airborne Particles in Relation to Traffic and Air Pollution Parameters, Environ. Sci. Technol., 16, 221-225 (1982). 

The case of protein synthesis, i.e., diffusion of many segments on the same one-dimensional lattice, is clearly recognized as a species of traffic problem. However, the existing traffic literature has been of no help to its solution. Indeed, only rather special types of solutions have presented themselves to date. On the other hand, methods for a full solution of the DNA synthesis problem, i.e., single-particle diffusion, are reasonably well known but not of much use, since they give solutions in terms of only slowly converging series. Nevertheless, the first two moments of the distribution of degrees of polymerization in the ensemble at each time are easily obtained. 

Particle physical properties typically change under the impact of smoke plume but these changes may not be specific for the wildfire smoke. In addition to biomass burning, particle mass or number concentration can increase due to the biogenic or other anthropogenic sources, e.g., traffic or industrial emissions. Chemical composition of particles is more unique to particle source, however, particles with similar chemistry can have different origin. Physical and chemical properties of the LRT biomass burning particles observed in Northern Europe are discussed below. Physical properties and the chemical components measured from the smoke particles are summarized in Table 2. The measurements of PM mass concentrations are excluded from Table 2 as nearly all the studies had some measurements of particle mass. 

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