About Road Dust
Dust kicked up by vehicles travelling on roads may make up 33% of air pollution. Road dust consists of deposition of vehicle exhausts and industrial exhausts, tire and brake wears, dust from paved roads or potholes and dust from construction sites. There are more than 3.9 million miles of roadway in the United States, according to the Federal Highway Administration. The Federal Highway Administration (FHWA - a division of the United States Department of Transportation) specializes in highway transportation. The agency's major activities are grouped into two "programs": The Federal-aid Highway Program and the Federal Lands Highway. Depending on the area of the country you're in, as much as 70% of that road mileage is unpaved.
National Air Quality and Emissions Trends Report states that those unpaved roads--which can cover a wide range of compositions, from compacted dirt to shale/slate to gravel--are responsible for more than 10 million tons of particulate matter emissions each year. Economic, logistical and even aesthetic realities indicate the impossibility of paving every mile of unpaved roadway in America. The goal, then, is to minimize the generation and spread of dust particles. Particles of the roadway itself will be continually ground smaller, until they approach the ten- to fifteen-micron danger size where they can more easily penetrate deep into the lungs. This is also the ideal size range for particles to stay airborne for longer periods of time--larger than this, they tend to settle more quickly and are less of an immediate hazard, although they are still subject to the same grinding/regrinding phenomenon.
How Can Road Dust Affect My Family And Community?
Particles larger than 2.5 microns can lodge in the upper respiratory area, where they may cause severe irritation. Effects may be especially pronounced in infants, the elderly and those with pre-existing conditions such as asthma. Particles this size may also be linked to some respiratory cancers. Particles smaller than 2.5 microns go deeper into the lungs, where they can damage epithelial cells (cells that form a thin surface coating on the outside of a body structure) and even pass into the bloodstream. Dust particles this small can elude all but the most specialized of filters. Those who live near unpaved roads or trails aren't the only people at risk from these particles. Studies indicate that human health isn't the only thing that suffers in the dispersion of road dust. Plants are typically dusty which can cause surrounding vegetation to become susceptible to chronic decreases in photosynthesis and growth, eventually leading to accelerated erosion in areas such as roadsides from lack of adequate stabilizing vegetation. Dust impacts not only the air, but the water as well, as it settles into nearby streams and rivers.
How Can I Reduce Road Dust?
The easiest way to reduce road dust is to reduce your speed. The efficiency of speed reduction as a dust control measure increases as the speed is reduced. Based on an initial speed of 40 miles per hour, reducing the speed limit to 20 miles per hour results in a 65% reduction in dust emissions; a reduction in the speed limit to 15 miles per hour results in an 80% reduction in dust emmissions (EPA, 1977; Orlemann er al., 1983).Waste products may also be used as a road dust control measure:
* Lignosulfonates (a waste product from the pulping industry which glues soil particles together);
* Used lubrication oil;
* Salt brines (from natural gas wells);
* Whey are currently being used.
* Fly ash (waste generated by the burning of coal in thermal power plants);
* Sulphur (waste generated by the petroleum industry);
* Rubber latex (waste generated during the manufacture of synthetic rubber);
* Calcium or magnesium carbonate (waste precipitated from water softening operations) are good candidates for future use.
Futher reasearch into the applicability of these products, including their environmental impact is needed.