Unpaved roads

Mechoulam R, Feigenbaum E. The unpaved road to the endogenous brain cannabinoid ligands, the anandamides. In Pertwee RG, ed. Cannabinoid Receptors. New York Academic Press, 1995b 233-258. 

Unpaved road dust or aerosols contributes to haze in class I airsheds. 

The people who are most at risk for health problems from particulate exposure are those who already have some form of respiratory disorder or heart disease, the elderly, and children. Such problems begin to appear when the ambient concentration of pollutants reaches about 40 pg/m for PM25 particulates and about 150 pg/m for PM particulates. Such concentrations are observed during dust storms, along dusty unpaved roads, and in areas with high levels of motor vehicle traffic, for instance. Increasing concentrations of both PM2 5 and PMj particulates result in more serious health problems, including asthma, bronchitis, emphysema, and cardiac problems. 

Dust from paved and unpaved roads is the most predominant source in Portland. Accurate emissions data is critical to the model s ability to account for all of the measured mass, as well as to the development of a successful strategy. Although the CMB model cannot distinguish between dust emissions from paved and unpaved roads, it can typically assign total dust impacts to within a 5-6% uncertainty. Leaded automotive tailpipe exhaust was selected because it can be accurately estimated by CMB and is the third most abundant contributor to the annual particulate mass, after road dust and vegetative burning. 

Road dust underpredictions, based on the initial EPA generalized paved road dust factor, were the most serious problem. Since there are very few unpaved roads within the AQMA, attention turned to upward adjustment of the paved road dust emission factor. 

Finally, data from studies in Seattle, Washington (.8) suggested a 10 to 20 fold increase in street dust emissions in heavy Industrial areas as compared to commercial, land use areas. Adjustments were made to each grid s emissions based on information from land use maps and detailed data on unpaved roads. 

Road dust emission inventory errors were corrected after comparing dispersion model and CMB results. Road dust emissions were increased by 2300 tons in Medford as a result of emission factor adjustments and changes in the unpaved road dust inventory. 

In Eugene, new measurements of traffic volume and vehicle speeds on unpaved roads led to a 2600 ton per year reduction in road dust emissions. 

In a search for sources of alkaline materials in rural air and rain, we have sampled and performed multi-element analyses on ambient particulate matter and potential source materials. Ambient aerosols were sampled daily using single Nuclepore filters or Florida State University "streakers." Samples of soil and unpaved road materials were also collected and analyzed. The samples were analyzed by various multi-element methods, including ion-and proton-induced X-ray emission and X-ray fluorescence, as well as by atomic absorption spectrophotometry. Visual observations, as well as airborne elemental concentration distributions with wind direction and elemental abundances in aerosols and source materials, suggested that soil and road dust both contribute to airborne Ca. Factor analysis was able to identify only a "crustal" source, but a simple mass balance suggested that roads are the major source of Ca in rural central Illinois in summer. 

Road materials were gathered from 9 locations on unpaved roads in the vicinity of the sampling site. At each location, dust from the roadbed was scraped into a polyethylene sample bag from 5 or more spots over a 10 m area. These materials were also air dried and sieved Identically to the soil materials, but not crushed. Visual inspections of the road surface suggested that samples from 8 of the 9 sites were primarily crushed limestone rock. The remaining site consisted primarily of washed gravel derived from glacial deposits. An inventory of unpaved road surface materials within 5 km of the sampling site indicated that approximately 80% consisted of crushed limestone. 

Assuming all unpaved road surfaces are crushed limestone Results... 

In the United States in 1996, the total emissions of PMI() were 31 X 106 short tons per year, or 28 Tg per year (EPA, 1997). Fugitive dust sources such as unpaved roads make up 90% of the total PM1() emissions. Figure 2.15 shows sources of PM1() in the United States in 1996 split into (a) nonfugitive dust sources ( 10% of the total) and (b) fugitive dust sources (EPA, 1997). 

Kuhns H, Gillies J, Etyemezian V, Nikolich G, King J, Zhu D, Uppapalli S, Engelbrecht J, Kohl S (2010) Effect of soil type and momentum on unpaved road particulate matter emissions from wheeled and tracked vehicles. Aerosol Sci Technol 44(3) 187-196... 

Kuhns H, Etyemezian V, Green M, Hendrickson K, McGown M, Barton K, Pitchford M (2003) Vehicle-based road dust emission measurement - part II effect of precipitation, wintertime road sanding and street sweepers on inferred PM10 emission potentials from paved and unpaved roads. Atmos Environ 37 4573M582... 

Claibom C, Mitra A, Adams G, Bamesberger L, Allwine G, Kantamaneni R, Lamb B, Westberg H (1995) Evaluation of PM10 emission rates from paved and unpaved roads using tracer techniques. Atmos Environ 29(10) 1075-1089... 

Particulate matter (PM-10, PM-2.5) is made up of dust, smoke and soot. The source is wood burning, diesel and other fuels, industrial plants, agriculture (plowing, burning of fields), unpaved roads. Health effects include nose and throat irritation, lung damage, bronchitis, and early death. Environmental effect... 

At Oak Grove School, I had my first teaching experience. The school was four miles (6.4 km) of unpaved roads from Woodstock and close to where J H Johnston had his three hundred acre (120 hectare) farm. Usually, my mother drove me to and from the school, or I rode one of Grandpa Dial s horses, but for several days I had boarded at a farmhouse near the school, because Noonday Creek had flooded the road Kevin Boston and I had tried to wade through flood waters to reach my mother s car on the other side, but the water was too deep (Figure 1.2(a)). 

From paved roads, unpaved roads, and construction. 

Dust from paved and unpaved roads Construction dust... 

Use Foam producer, emulsifier, adhesives, tanning agent, binder for briquets, cores, unpaved roads, source of torula yeast. 

Impacts (stones hitting against the base of the vehicle when driving on unpaved roads, potholes, accidents) cause mechanical frequencies with a broad spectrum. Resonant properties of the mounting location in the car amplify these disturbances. If the frequencies match with the sensors frequencies, this can lead to malfunction of the sensor, even at nominally slight external accelerations. 

South Carolina soil, Berkely County, South Carolina Soil from a marshy area 50 ft off an unpaved road numbered 220A in the Wambaw-Hunting Unit of the Francis Marion National Forest. The sample was collected by a cleaned shovel at a depth of 10-20 cm. 

Nevada soil, Nevada Obtained with a cleaned shovel at a depth of 10-20 cm. The site was located 40 mi east of Lee Vining, California, 1 mile off Nevada Route 31, and 50 m from a unpaved road. This is a sandy, desert environment. 

Sources Combustion (coal, oil, gasoline, diesel, wood) Gas-to-particle conversion of NO, S03, and VOCs Smelters, mills, etc. Resuspension of industrial dust and soil Suspension of soil (farming, mining, unpaved roads) Biological sources Construction/demolition Ocean spray... 

Emissions from motor vehicles are among the major contributors to fine particle concentrations in the urban atmosphere (Schauer et al. 1996 Kleeman et al. 2000) they make substantial direct and indirect contributions to ambient PM levels. Direct particulate emission sources from vehicles include their exhaust (Mulawa et al. 1997 Sagebiel et al. 1997), the mechanical wear of tires and brakes (Rogge et al. 1993 Garg et al. 2000), and the ejection of particles from the pavement (Kupiainen et al. 2005) and unpaved road shoulders (Moosmiiller et al. 1998) as well as re-suspension processes (Nicholson et al. 1989 Stembeck et al. 2002). Indirect contributions include the emission of reactive gases, both organic and inorganic, which form secondary particulate matter via atmospheric transformations. 

Gillies JA, Etyemezian V, Kuhns H et al (2005) Effect of vehicle characteristics on unpaved road dust emissions. Atmos Environ 39 2341-2347... 

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