Atmospheric or wind-borne
fugitive dust, also known as
aeolian dust, comes from dry regions where high-speed winds can remove mostly silt-sized material, abrading susceptible surfaces. This includes areas where
grazing,
ploughing,
vehicle use, and other
human behaviors have further destabilized the
land, though not all source areas have been largely affected by
anthropogenic impacts. Dust-producing surfaces cover one-third of the global land area. These are made up of
hyper-arid regions like the
Sahara, which covers 0.9 billion hectares, and
drylands, which occupy 5.2 billion hectares. Dust in the atmosphere is produced by
saltation and
abrasive sandblasting of sand-sized grains, and it is transported through the
troposphere. This airborne dust is considered an
aerosol, and once in the atmosphere, it can produce strong local
radiative forcing. Saharan dust, in particular, can be transported and deposited as far as the
Caribbean and the
Amazon basin and may affect air
temperature, cause ocean cooling, and alter rainfall amounts. In Iran, the dust directly affects more than 5 million people and has become a serious government issue recently. In the
Khuzestan province, it has led to the severe increase of
air pollution. The amount of
pollutants in the air has surpassed more than 50 times the normal level several times in a year. Recently, initiatives such as Project-Dust have been established to study dust in the Middle East directly. The continuation of drought has caused
water scarcity or drying up of some wetlands and lakes such as
Hamon and
Urmia Lake. This has turned them into centers of dust.
Roads Dust kicked up by vehicles traveling on
roads is a significant source of harmful
air pollution. Road dust consists of deposits of vehicle and industrial
exhaust gas, particles from
tire and
brake wear,
dust from paved roads or
potholes, and dust from
construction sites. Road dust is a significant contributor to the generation and release of
particulates into the atmosphere. Control of road dust is a significant challenge in
urban areas, and also in other locations with high levels of vehicular traffic upon unsealed roads, such as mines and
landfills. "Engine exhaust emissions, especially from those operating on diesel fuel, can be a significant source of fine particle generation from construction sites." Construction and
demolition activities can also produce a large amount of
construction waste. The dust and
particulates can become
fugitive and airborne with
vehicle movements both on and outside the sites, especially when it is windy and dry. Road dust may be suppressed by mechanical methods like
street sweeper, vehicles equipped with
vacuum cleaners,
vegetable oil sprays, or with water sprayers.
Calcium chloride can be used. Improvements in
automotive engineering have reduced the amount of
PM10s produced by road traffic; the proportion representing re-suspension of existing particulates has increased as a result. ==Coal==