What is haze?
Visibility impairment is one of the most obvious indicators of pollution in the air. This often occurs as a result of haze, which obscures the clarity, color, texture, and form of what we see. Some haze-causing pollutants (mostly fine particles) are directly emitted into the atmosphere by activities such as electric power generation, various industrial and manufacturing processes, truck and auto emissions, burning related to forestry and agriculture, and construction. Others are formed when gases emitted to the air form particles as they are carried downwind. Examples include sulfate, formed from sulfur dioxide, and nitrates, formed from nitrogen oxides. Without haze, a natural visual range is approximately 140 miles in the West and 90 miles in the East. However, in many parts of the United States, fine particles have significantly reduced the range that people can see. In the West, the current range is 33-90 miles, and in the East, the current range is only 14-24 miles.
Haze is caused when sunlight encounters tiny pollution particles in the air. Some light is absorbed by the particles. Other light is scattered before it reaches an observer. More pollutants in the air mean more absorption and scattering of light, which reduce the clarity and color of what we see. Some types of particles, such as sulfates, scatter more light than others, particularly during humid conditions. The degree of impairment depends on a number of factors—the concentration, size, and chemical composition of these fine particles, relative humidity, and the angle at which the sunlight penetrates the haze. In rural parts of the eastern United States, fine particle sulfate accounts for most of the visibility impairment. Two-hundred times smaller in diameter than a human hair, these particles are just the right size to scatter visible light. Often, haze is confused with mist and fog. During the early morning or after rain showers when temperatures are low and humidity is high, mist a
Haze is caused when sunlight encounters tiny pollution particles in the air. Some light is absorbed by particles. Other light is scattered away before it reaches an observer. More pollutants mean more absorption and scattering of light, which reduce the clarity and color of what we see. Some types of particles such as sulfates, scatter more light, particularly during humid conditions. Air pollutants come from a variety of natural and manmade sources. Natural sources can include windblown dust, and soot from wildfires. Manmade sources can include motor vehicles, electric utility and industrial fuel burning, and manufacturing operations. Some haze-causing particles are directly emitted to the air. Others are formed when gases emitted to the air form particles as they are carried many miles from the source of the pollutants. Some of the pollutants which form haze have also been linked to serious health problems and environmental damage. Exposure to very small particles in the air have bee
Regional haze pollution, mainly in the form of sulfate, organic and nitrate fine particles, results in poor visibility from mountain tops as well as negative human health impacts. Haze is composed of very small fine particles, smaller than 2.5 micrometers (µm) (over 20 times smaller in diameter than a human hair) that are suspended in the air. These particles originate from a variety of sources, some natural, but much of it originates from power plant and automobile emissions. Haze is generally composed of 5 major components: sulfate aerosol, nitrate aerosol, organic carbon aerosol, elemental carbon, and dust from the earth’s crust.
Haze is caused when sunlight encounters tiny pollution particles in the air. Some light is absorbed by particles. Other light is scattered away before it reaches an observer. More pollutants mean more absorption and scattering of light, which reduce the clarity and color of what we see. Some types of particles such as sulfates, scatter more light, particularly during humid conditions. Where does haze-forming pollution come from? Air pollutants come from a variety of natural and manmade sources. Natural sources can include windblown dust, and soot from wildfires. Manmade sources can include motor vehicles, electric utility and industrial fuel burning, and manufacturing operations. Particulate matter pollution is the major cause of reduced visibility (haze) in parts of the United States, including many of our national parks. Find out more about particulate pollution. Some haze-causing particles are directly emitted to the air. Others are formed when gases emitted to the air form particle
