| • Science | • People | • Locations | • Timeline |
right Victorian-era London was notorious for its thick smogs, or 'pea-soupers', a fact that is often recreated to add an air of mystery to a period costume drama .
Smog is a kind of heavy air pollution. Under special weather conditions, it can stay for an extended period of time over densely populated cities, such as London, Los Angeles, Athens or the Ruhr area. The word "smog" is a portmanteau constructed from the words " smoke" and " fog", although modern usage of the term does not require either a smoke or fog component and "smog" is often used as shorthand for "air pollution".
Photochemical smog is caused when two kinds of air pollution combine in the presence of sunlight. The first kind is the particulates and nitric oxides from the exhaust of fossil fuelFossil fuels are coal and hydrocarbon fuels or hydrocarbon containing fuels such as petroleum (including natural gas). The utilization of fossil fuels has fueled industrial development and largely supplanted water driven mills and wood or peat burning for-burning engines in carsAn automobile usually called a car (an old word for carriage) or a truck is a wheeled vehicle that carries its own engine. Older terms include horseless carriage and motor car with "motor" referring to what is now usually called the engine. The act of ope, trucks, coalCoal is a fossil fuel extracted from the ground by mining. It is a readily combustible black or brownish-black sedimentary rock. It is composed primarily of carbon and hydrocarbons, along with assorted other elements, including sulfur. Often associated wi power plants, and industrial manufacturing factories. The second kind is the emissions of volatile organic compoundVolatile organic compounds Volatile organic compounds VOCs are chemical compounds that have a high vapor pressure and low water solubility. The group includes a wide range of carbon-based molecules, such as aldehydes, keytones, cyclic compunds and long-chs from paintFor information on the U. borough, see Paint, Pennsylvania. Paint is the general term for a family of products used to protect and add color to an object or surface by covering it with a pigmented coating. As a verb, painting is the application of paint.s, solventA solvent is a liquid that dissolves a solute. The solvent is the component of a solution that is present in greater amount. See solution. Perhaps the most common solvent in everyday life is water. Many other solvents are organic compounds, such as benzens, pesticideA pesticide is a chemical used to control, to repel, to attract or to kill pests, for example, insects, weeds, birds, mammals, fish, or microbes, that are considered a nuisance. Pesticides are usually, but not always, poisons. Examples of pesticides herbis and other chemicals. According to [1], gasoline and other petroleum-based chemicals and solvents often vaporize directly into the atmosphere, contributing to ozone. Two major residential sources are gasoline-powered lawnmowers and the starter fluid for backyard grills.
Smog can form in almost every climate, but is far worse during periods of warmer, sunnier weather when the upper air is warm enough to inhibit vertical circulation. It is especially prevalent in geologic basins encircled by hills or mountains.
Episodes of smog became common in London in the late 19th century and were nicknamed as "pea-soupers". The Great Smog of 1952 darkened the skies over London and killed approximately 12,000 people. The British government first blamed a flu epidemic, reluctant to admit that coal smoke was to blame. In 1956 the Clean Air Act introduced smokeless zones to the capital. Only smokeless fuels could be used in these areas. Consequently, reduced sulphur dioxide levels made the intense and persistent London smog a thing of the past. Smog caused by traffic pollution, however, does occur in modern London.
Smog is a problem in a number of cities and continues to harm life. According to the U.S. EPA, air is unhealthy because of smog if it contains more than 80 parts per billion (ppb) of ozone (the primary component of smog) [2], more than 53 ppb of nitrogen dioxide or 80 ppb particulates. High levels of smog aggravate and even cause human respiratory problems, including emphysema, bronchitis, and asthma. Hospital admissions and respiratory deaths often increase during periods when ozone levels are high [3].
An erupting volcano can also emit high levels of sulfur dioxide, creating volcanic smog, or vog.