Hummer

Hummers were originally built by AM General Corporation, which was formerly AMC Jeep's General Products division,^[1] in its Mishawaka, Indiana assembly plant. They were created under a contract for the United States armed forces. The first model, the Hum-Vee, was built in a variety of military-based equipment and versions. These included troop carriers, gun turrets and radar. The U.S. military, on receiving their quota, have adapted some of the vehicles, including modifications to facilitate a directional microwave crowd control beam (Active Denial System).

AM General had planned to sell a civilian version of the Hum-Vee as far back as the late 1980s. In 1990, two matching white Hum-Vees were driven from London to Beijing over the rough roads of central Soviet Union. The Hummers made the trip with ease, for they were built to drive on off-road terrain. The highlights of this journey were broadcast in the United States on ESPN. This publicity would pale in comparison to the attention that the HMMWV received for its service in Operation: Desert Storm the following year. Also, a privately-owned Hum-Vee was modified into the first Snow-Vee, including the addition of caterpillar tracks, a new rear compartment and a new engine. This vehicle was designed for use in and just below the Arctic Circle, and the Antarctic.

In 1992, AM General began selling a civilian version of the M998 High Mobility Multipurpose Wheeled Vehicle (HMMWV or Hum-Vee) vehicle to the public under the brand name "Hummer", called the Hummer H1.

In 1998, AM General sold the brand name to General Motors, but continued to manufacture the vehicles. GM is responsible for the marketing and distribution of all Hummers produced by AM General. In the next few years, GM introduced two new homegrown models, the H2 and H3, and renamed the original vehicle H1. AM General continued to build the H1 until it was discontinued in 2006,^[2] and is contracted by GM to produce the H2. The H3 is built in Shreveport, LA alongside the Chevrolet Colorado and GMC Canyon pickups, with which it shares the GMT-355 platform (custom modified and designated GMT-345)

Honda

Honda Motor Company, Ltd. (本田技研工業株式会社 ,Honda Giken Kōgyō Kabushiki-gaisha^?, Honda Technology Research Institute Company, Limited) listen (help·info) (TYO: 7267 NYSE: HMC) is a multinational corporation headquartered in Japan.

The company manufactures automobiles, motorcycles, trucks, scooters, robots, jets and jet engines, ATV, water craft, electrical generators, marine engines, lawn and garden equipment, and aeronautical and other mobile technologies. Honda's line of luxury cars are branded Acura in North America and Ben Tian in China. More recently they have ventured into mountain bikes.

Honda is the 6th largest automobile manufacturer in the world as well as the largest engine-maker in the world, producing more than 14 million internal combustion engines each year. In August 2008, Honda surpassed Chrysler as the 4th largest automobile manufacturer in the United States. Currently, Honda is the second largest manufacturer in Japan behind Toyota and ahead of Nissan.

Mercedes-Benz

Since its inception, Mercedes-Benz had a reputation for quality and durability. Objective measures looking at passenger vehicles such as J.D. Power surveys demonstrated a downturn in reputation in this area in the late 1990s and early 2000s. By mid-2005, Mercedes temporarily returned to the industry average for initial quality, a measure of problems after the first 90 days of ownership, according to J.D. Power.^[2] In J.D. Power's Initial Quality Study for the first quarter of 2007, Mercedes showed dramatic improvement by climbing from 25th to 5th place, surpassing quality leader Toyota and earning several awards for its models. ^[3] For 2008, Mercedes-Benz's initial quality rating improved by yet another mark, now in fourth place.^[4] On top of this accolade, it also received the Platinum Plant Quality Award for its Mercedes’ Sindelfingen, Germany assembly plant.^[4] As of 2009, Consumer Reports of the United States has changed their reliability ratings for several Mercedes-Benz vehicles to "average," and recommending the E-Class and the S-Class

BMW

After World War I, BMW was forced to cease aircraft (engine) production by the terms of the Versailles Armistice Treaty.^[2] The company consequently shifted to motorcycle production in 1923 once the restrictions of the treaty started to be lifted,^[3] followed by automobiles in 1928.^{[citation needed]}

The circular blue and white BMW logo or roundel is often alleged to portray the movement of an airplane propeller, to signify the white blades cutting through the blue sky - an interpretation that BMW adopted for convenience in 1929, which was actually twelve years after the roundel was created.^[4][5] In fact, the emblem evolved from the circular Rapp Motorenwerke company logo, from which the BMW company grew. The Rapp logo was combined with the blue and white colors of the flag of Bavaria to produce the BMW roundel so familiar today.

BMW's first significant aircraft engine was the BMW IIIa inline-six liquid-cooled engine of 1918, much preferred for its high-altitude performance.^{[citation needed]} With German rearmament in the 1930s, the company again began producing aircraft engines for the Luftwaffe. Among its successful WWII engine designs were the BMW 132 and BMW 801 air-cooled radial engines, and the pioneering BMW 003 axial-flow turbojet, which powered the tiny, 1944-45-era jet-powered "emergency fighter", the Heinkel He 162 Salamander, and was tested in the A-1b version of the world's first jet fighter, the Messerschmitt Me 262.^{[citation needed]}

By 1959 the automotive division of BMW was in financial difficulties and a shareholders meeting was held to decide whether to go into liquidation or find a way of carrying on. It was decided to carry on and to try to cash in on the current economy car boom enjoyed so successfully by some of Germany's ex-aircraft manufacturers such as Messerschmitt and Heinkel. Therefore the rights to manufacture the tiny Italian Iso Isetta were bought using a modified form of BMW's own motorcycle engine. This was moderately successful and helped the company get back on its feet. The dominating shareholder of the BMW Aktiengesellschaft since 1959 is the Quandt family, which owns about 46% of the stock. The rest is in public float

Water pollution

Water pollution is the contamination of water bodies such as lakes, rivers, oceans, and groundwater caused by human activities, which can be harmful to organisms and plants that live in these water bodies. It occurs when pollutants are discharged directly into water bodies without treating it first.

Water pollution is a major problem in the global context. It has been suggested that it is the leading worldwide cause of deaths and diseases,^[1][2] and that it accounts for the deaths of more than 14,000 people daily.^[2] In addition to the acute problems of water pollution in developing countries, industrialized countries continue to struggle with pollution problems as well. In the most recent national report on water quality in the United States, 45 percent of assessed stream miles, 47 percent of assessed lake acres, and 32 percent of assessed bay and estuarine square miles were classified as polluted.^[3]

Water is typically referred to as polluted when it is impaired by anthropogenic contaminants and either does not support a human use, like serving as drinking water, and/or undergoes a marked shift in its ability to support its constituent biotic communities, such as fish. Natural phenomena such as volcanoes, algae blooms, storms, and earthquakes also cause major changes in water quality and the ecological status of water. Water pollution has many causes and characteristics

Vehicle-to-grid

Vehicle-to-grid (V2G) describes a system in which power can be sold to the electrical power grid by an electric-drive motor vehicle that is connected to the grid when it is not in use for transportation.^[1] Alternatively, when the car batteries need to be fully charged, the flow can be reversed and electricity can be drawn from the electrical power grid to charge the battery.

Vehicle-to-grid can be used with such gridable vehicles, this is, plugin vehicles (this is, electric vehicles as Battery Electric Vehicles (BEV) or Plug-in hybrid electric vehicles), with grid capacity. Since most vehicles are parked an average of 95 percent of the time, their batteries could be used to let electricity flow from the car to the power lines and back, with a value to the utilities of up to $4,000 per year per car. ^[2]

One notable V2G project in the United States is at the University of Delaware, where a V2G team headed by Dr. Willett Kempton has been conducting on-going research. Their goals are to educate about the environmental and economic benefits of V2G and enhance the product market.^[3] Other investigators are the Pacific Gas and Electric Company, Xcel Energy, the National Renewable Energy Laboratory, and the University of Warwick

Sustainable transport

Sustainable transport is a concept developed in reaction to things that have gone visibly wrong with transportation policy, practice and performance through much the world over the last half of the twentieth century. Urban transport systems based around the car have proved unsustainable, consuming excessive energy, affecting the health of populations, and delivering a declining level of service despite increasing investments. Many of these negative impacts fall disproportionately on those social groups who are also least likely to own and drive cars.^[1][2][3]

The sustainable transport movement, part of the environmental movement, has gradually gained in force over the last decade and a half, and has in the process started to shift the emphasis in public spending and actions away from building and supply, to management and demand. The values of respect for the environment and prudent use of natural resources are central, with varying degrees of urgency expressed by different actors and interests. That said, it is still very much a minority movement and most actual expenditures in the sector are determined by criteria other than sustainability.

What is clear is that sustainable transportation mainly refers to human behavior, not to technology.^[4] In that sense, a behavioral approach considers not only a set of non-polluting and human scaled green transport choices, regardless of the means and technology used, but also a set of reinforcers both individual and social to promote these choices.

Soil contamination

Soil contamination is caused by the presence of man-made chemicals or other alteration in the natural soil environment. This type of contamination typically arises from the rupture of underground storage tanks, application of pesticides, percolation of contaminated surface water to subsurface strata, oil and fuel dumping, leaching of wastes from landfills or direct discharge of industrial wastes to the soil. The most common chemicals involved are petroleum hydrocarbons, solvents, pesticides, lead and other heavy metals. This occurrence of this phenomenon is correlated with the degree of industrializations and intensities of chemical usage.

The concern over soil contamination stems primarily from health risks, both of direct contact and from secondary contamination of water supplies^[1]. Mapping of contaminated soil sites and the resulting cleanup are time consuming and expensive tasks, requiring extensive amounts of geology, hydrology, chemistry and computer modeling skills.

It is in North America and Western Europe that the extent of contaminated land is most well known, with many of countries in these areas having a legal framework to identify and deal with this environmental problem; this however may well be just the tip of the iceberg with developing countries very likely to be the next generation of new soil contamination cases.

Society of Automotive Engineers

SAE International (SAE) is a professional organization for mobility engineering professionals in the aerospace, automotive, and commercial vehicle industries. The Society is a standards development organization for the engineering of powered vehicles of all kinds, including cars, trucks, boats, aircraft, and others. Membership is open to the public for those particularly interested in Human Factors and Ergonomic Standards

n the early 20th century there were dozens of automobile manufacturers in the United States. Many of these manufacturers joined trade groups that allowed them to promote the industry and raise public awareness related to the automobile. A need for patent protection and the development of engineering standards emerged during this time.

Two magazine men of the era: Peter Heldt of The Horseless Age, and Horace Swetland of The Automobile advocated the creation of SAE. Heldt wrote an editorial in June 1902 in which he said, "Now there is a noticeable tendency for automobile manufacturers to follow certain accepted lines of construction, technical questions constantly arise which seek solution from the cooperation of the technical men connected with the industry. These questions could best be dealt with by a technical society. The field of activity for this society would be the purely technical side of automobiles." Likewise, Swetland used his editorial power to drum up support for the creation of an organization like SAE. Swetland went on to become one of the founding officers in the organization.

Starting out as the Society of Automobile Engineers in 1905, SAE's original purpose was to promote the use of standards in the nascent automobile industry (initially in the United States) and to promote the better interchange of ideas and expertise, in a similar manner to many other technical societies.

Noise pollution

Noise pollution (or environmental noise) is displeasing human-, animal- or machine-created sound that disrupts the activity or balance of human or animal life. A common form of noise pollution is from transportation, principally motor vehicles.^[1] The word noise comes from the Latin word noxia meaning "injury" or "hurt".

The source of most noise worldwide is transportation systems, motor vehicle noise, but also including aircraft noise and rail noise.^[2][1] Poor urban planning may give rise to noise pollution, since side-by-side industrial and residential buildings can result in noise pollution in the residential area.

Other sources are car alarms, office equipment, factory machinery, construction work, groundskeeping equipment, barking dogs, appliances, power tools, lighting hum, audio entertainment systems, loudspeakers and noisy people.

Light pollution

It obscures the stars in the night sky for city dwellers, interferes with astronomical observatories, and, like any other form of pollution, disrupts ecosystems and has adverse health effects. Light pollution can be divided into two main types: 1) annoying light that intrudes on an otherwise natural or low-light setting and 2) excessive light (generally indoors) that leads to discomfort and adverse health effects. Since the early 1980s, a global dark-sky movement has emerged, with concerned people campaigning to reduce the amount of light pollution.

Light pollution is a side effect of industrial civilization. Its sources include building exterior and interior lighting, advertising, commercial properties, offices, factories, streetlights, and illuminated sporting venues. It is most severe in highly industrialized, densely populated areas of North America, Europe, and Japan and in major cities in the Middle East and North Africa like Cairo, but even relatively small amounts of light can be noticed and create problems. Like other forms of pollution (such as air, water, and noise pollution) light pollution causes damage to the environment

Urban heat island

Developed environments like concrete and black roads absorb and store heat more readily than natural land cover because of their heat capacity. The urban heat island phenomenon traps heat in thermal mass and is ultimately emitted back into the urban air especially at night.^[3] This hot city phenomenon has far-reaching environmental sustainability and human livability implications, ranging from the aggravation of health problems such as hyperthermia, increasing the intensity of urban air pollution, and contributing to extreme heat waves.^[4] Excess heat also adds to the ever-increasing use of air conditioners, with higher demands on the energy supply, potentially resulting in brownouts and higher greenhouse gas emissions.^[5]

Some causes of urban heat islands are the displacement of trees and vegetation to make way for development and even prevailing weather conditions. Heat from vehicles, manufacturing plants, and thermal power stations also contribute to excess heat in urban areas.^[5] Land use is a key attribute for the development of locally significant heat islands

Car donation

Car donation is the practice of giving away no-longer-wanted automobiles to charity organizations. In the United States, charitable donations provide a tax benefit; as such, this type of giving has become very popular. For values less than $500, the value of the tax deduction comes from the donor's own estimate of the car's value, even if the charity receives less money from actually selling the car. Deductions for donations over this amount are limited to the sale amount of the vehicle (usually at auction). Some critics have claimed that this is essentially a tax shelter. However, non-profit organizations in the US have come to rely increasingly upon the revenue from car donations. This type of donation has become increasingly widespread in the U.S.; in 2000, 733,000 taxpayers reduced their taxes by $654 million.

Many charities run donation programs. Some have their own car lots which sell the donated cars but many have their donations processed through auto auction companies. Many processing companies also collect and sell donated cars and distribute the money to a charity the donor indicates. The processing company typically takes a percentage of the sale value of the car, but these programs allow charities without their own facilities or staff dedicated to automotive donation fund raising to benefit from vehicle donation programs.

Although advertised as an easy way to dispose of an old car, donors need to fulfill certain post-donation requirements to qualify for the tax deduction such as obtaining a written acknowledgment of the car's subsequent sale by the charity,^[1] and itemizing instead of taking the standard deduction.^[2] Ideally, donors should also investigate how much money from the sale of the car goes to the auction processor and how much actually benefits the charity's programs, as opposed to its administrative overhead

Car classification

Car classification is subjective since many vehicles fall into multiple categories or do not fit well into any. Not all car types are common in all countries and names for the same vehicle can differ by region. Furthermore, some descriptions may be interpreted differently in different places. Broadly speaking, there are a set of classifications which are widely understood in North America, and another set which are somewhat understood in English-speaking contexts in Europe. Some terms borrowed from non-English languages may have different meanings when used in their native language.

Alternatives to the automobile

Established alternatives for some aspects of automobile use include public transit (buses, trolleybuses, trains, subways, monorails, tramways), cycling, walking, rollerblading, skateboarding, horseback riding and using a velomobile. Car-share arrangements and carpooling are also increasingly popular–the U.S. market leader in car-sharing has experienced double-digit growth in revenue and membership growth between 2006 and 2007, offering a service that enables urban residents to "share" a vehicle rather than own a car in already congested neighborhoods.^[39] Bike-share systems have been tried in some European cities, including Copenhagen and Amsterdam. Similar programs have been experimented with in a number of U.S. Cities.^[40] Additional individual modes of transport, such as personal rapid transit could serve as an alternative to automobiles if they prove to be socially accepted

Effects on children

Cities around the world with high exposure to air pollutants have the possibility of children living within them to develop asthma, pneumonia and other lower respiratory infections as well as a low initial birth rate. Protective measures to ensure the youths' health are being taken in cities such as New Delhi, India where buses now use compressed natural gas to help eliminate the “pea-soup” smog.^[23] Research by the World Health Organization shows there is the greatest concentration of particulate matter particles in countries with low economic world power and high poverty and population rates. Examples of these countries include Egypt, Sudan, Mongolia, and Indonesia. The Clean Air Act was passed in 1970, however in 2002 at least 146 million Americans were living in areas that did not meet at least one of the “criteria pollutants” laid out in the 1997 National Ambient Air Quality Standards.^[24] Those pollutants included: ozone, particulate matter, sulfur dioxide, nitrogen dioxide, carbon monoxide, and lead. Because children are outdoors more and have higher minute ventilation they are more susceptible to the dangers of air pollution.

The Great Smog of 1952

Early in December 1952, a cold fog descended upon London. Because of the cold, Londoners began to burn more coal than usual. The resulting air pollution was trapped by the inversion layer formed by the dense mass of cold air. Concentrations of pollutants, coal smoke in particular, built up dramatically. The problem was made worse by use of low-quality, high-sulphur coal for home heating in London in order to permit export of higher-quality coal, because of the country's tenuous postwar economic situation. The "fog", or smog, was so thick that driving became difficult or impossible.^[21]. The extreme reduction in visibility was accompanied by an increase in criminal activity as well as transportation delays and a virtual shut down of the city. During the 4 day period of fog, at least 4,000 people died as a direct result of the weather.

Effects on COPD

Chronic obstructive pulmonary disease (COPD) include diseases such as chronic bronchitis, emphysema, and some forms of asthma.^[18]

A study conducted in 1960-1961 in the wake of the Great Smog of 1952 compared 293 London residents with 477 from towns reporting low death rates from chronic bronchitis (Gloucester, Peterborough, and Norwich). All subjects were male postal workers aged 40 to 59. Compared to the subjects from the outlying towns, the London subjects exhibited more severe respiratory symptoms (including cough, phlegm, and dyspnea), reduced lung function (FEV₁ and peak flow rate), and increased sputum production and purulence. The differences were more pronounced for subjects aged 50 to 59. The study controlled for age and smoking habits, and so concluded that local air pollution was the most likely cause of the observed differences.^[19]

It is believed that much like cystic fibrosis, by living in a more urban environment serious health hazards become more apparent. Studies have shown that in urban areas patients suffer mucus hypersecretion, lower levels of lung function, and more self diagnosis of chronic bronchitis and emphysema

Effects on cystic fibrosis

A study from 1999 to 2000 by the University of Washington showed that patients near and around particulate matter air pollution had an increased risk of pulmonary exacerbations and decrease in lung function.^[16] Patients were examined before the study for amounts of specific pollutants like Pseudomonas aeruginosa or Burkholderia cenocepacia as well as their socioeconomic standing. Participants involved in the study were located in the United States in close proximity to an Environmental Protection Agency.^{[clarification needed]} During the time of the study 117 deaths were associated with air pollution. A trend was noticed that patients living closer or in large metropolitan areas to be close to medical help also had higher level of pollutants found in their system because of more emissions in larger cities. With cystic fibrosis patients already being born with decreased lung function everyday pollutants such as smoke emissions from automobiles, tobacco smoke and improper use of indoor heating devices could add to the disintegration of lung function

Health effects

The World Health Organization states that 2.4 million people die each year from causes directly attributable to air pollution, with 1.5 million of these deaths attributable to indoor air pollution.^[8] "Epidemiological studies suggest that more than 500,000 Americans die each year from cardiopulmonary disease linked to breathing fine particle air pollution. . ."^[9] A study by the University of Birmingham has shown a strong correlation between pneumonia related deaths and air pollution from motor vehicles.^[10] Worldwide more deaths per year are linked to air pollution than to automobile accidents.^{[citation needed]} Published in 2005 suggests that 310,000 Europeans die from air pollution annually.^{[citation needed]} Direct causes of air pollution related deaths include aggravated asthma, bronchitis, emphysema, lung and heart diseases, and respiratory allergies.^{[citation needed]} The US EPA estimates that a proposed set of changes in diesel engine technology (Tier 2) could result in 12,000 fewer premature mortalities, 15,000 fewer heart attacks, 6,000 fewer emergency room visits by children with asthma, and 8,900 fewer respiratory-related hospital admissions each year in the United States

Indoor air quality (IAQ)

A lack of ventilation indoors concentrates air pollution where people often spend the majority of their time. Radon (Rn) gas, a carcinogen, is exuded from the Earth in certain locations and trapped inside houses. Building materials including carpeting and plywood emit formaldehyde (H₂CO) gas. Paint and solvents give off volatile organic compounds (VOCs) as they dry. Lead paint can degenerate into dust and be inhaled. Intentional air pollution is introduced with the use of air fresheners, incense, and other scented items. Controlled wood fires in stoves and fireplaces can add significant amounts of smoke particulates into the air, inside and out. Indoor pollution fatalities may be caused by using pesticides and other chemical sprays indoors without proper ventilation.

Carbon monoxide (CO) poisoning and fatalities are often caused by faulty vents and chimneys, or by the burning of charcoal indoors. Chronic carbon monoxide poisoning can result even from poorly adjusted pilot lights. Traps are built into all domestic plumbing to keep sewer gas, hydrogen sulfide, out of interiors. Clothing emits tetrachloroethylene, or other dry cleaning fluids, for days after dry cleaning.

Though its use has now been banned in many countries, the extensive use of asbestos in industrial and domestic environments in the past has left a potentially very dangerous material in many localities. Asbestosis is a chronic inflammatory medical condition affecting the tissue of the lungs. It occurs after long-term, heavy exposure to asbestos from asbestos-containing materials in structures. Sufferers have severe dyspnea (shortness of breath) and are at an increased risk regarding several different types of lung cancer. As clear explanations are not always stressed in non-technical literature, care should be taken to distinguish between several forms of relevant diseases. According to the World Health Organisation (WHO), these may defined as; asbestosis, lung cancer, and mesothelioma (generally a very rare form of cancer, when more widespread it is almost always associated with prolonged exposure to asbestos).

Emission factors

Air pollutant emission factors are representative values that attempt to relate the quantity of a pollutant released to the ambient air with an activity associated with the release of that pollutant. These factors are usually expressed as the weight of pollutant divided by a unit weight, volume, distance, or duration of the activity emitting the pollutant (e.g., kilograms of particulate emitted per megagram of coal burned). Such factors facilitate estimation of emissions from various sources of air pollution. In most cases, these factors are simply averages of all available data of acceptable quality, and are generally assumed to be representative of long-term averages.

The United States Environmental Protection Agency has published a compilation of air pollutant emission factors for a multitude of industrial sources.^[2] The United Kingdom, Australia, Canada and other countries have published similar compilations, as has the European Environment Agencya

Sources

Sources of air pollution refer to the various locations, activities or factors which are responsible for the releasing of pollutants in the atmosphere. These sources can be classified into two major categories which are:

Anthropogenic sources (human activity) mostly related to burning different kinds of fuel

• "Stationary Sources" include smoke stacks of power plants, manufacturing facilities (factories) and waste incinerators, as well as furnaces and other types of fuel-burning heating devices

• "Mobile Sources" include motor vehicles, marine vessels, aircraft and the effect of sound etc.

• Chemicals, dust and controlled burn practices in agriculture and forestry management. Controlled or prescribed burning is a technique sometimes used in forest management, farming, prairie restoration or greenhouse gas abatement. Fire is a natural part of both forest and grassland ecology and controlled fire can be a tool for foresters. Controlled burning stimulates the germination of some desirable forest trees, thus renewing the forest.

• Fumes from paint, hair spray, varnish, aerosol sprays and other solvents

• Waste deposition in landfills, which generate methane.Methane is not toxic; however, it is highly flammable and may form explosive mixtures with air. Methane is also an asphyxiant and may displace oxygen in an enclosed space. Asphyxia or suffocation may result if the oxygen concentration is reduced to below 19.5% by displacement

• Military, such as nuclear weapons, toxic gases, germ warfare and rocketry

Natural sources

• Dust from natural sources, usually large areas of land with little or no vegetation.
• Methane, emitted by the digestion of food by animals, for example cattle.
• Radon gas from radioactive decay within the Earth's crust.Radon is a colorless, odorless, naturally occurring, radioactive noble gas that is formed from the decay of radium. It is considered to be a health hazard.Radon gas from natural sources can accumulate in buildings, especially in confined areas such as the basement and it is the second most frequent cause of lung cancer, after cigarette smoking.

• Smoke and carbon monoxide from wildfires.
• Volcanic activity, which produce sulfur, chlorine, and ash particulates

Pollutants

An air pollutant is known as a substance in the air that can cause harm to humans and the environment. Pollutants can be in the form of solid particles, liquid droplets, or gases. In addition, they may be natural or man-made.^[1]

Pollutants can be classified as either primary or secondary. Usually, primary pollutants are substances directly emitted from a process, such as ash from a volcanic eruption, the carbon monoxide gas from a motor vehicle exhaust or sulfur dioxide released from factories.

Secondary pollutants are not emitted directly. Rather, they form in the air when primary pollutants react or interact. An important example of a secondary pollutant is ground level ozone - one of the many secondary pollutants that make up photochemical smog.

Note that some pollutants may be both primary and secondary: that is, they are both emitted directly and formed from other primary pollutants.

About 4 percent of deaths in the United States can be attributed to air pollution, according to the Environmental Science Engineering Program at the Harvard School of Public Health.

Major primary pollutants produced by human activity include:

• Sulfur oxides (SO_x) - especially sulfur dioxide, a chemical compound with the formula SO₂. SO₂ is produced by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide. Further oxidation of SO₂, usually in the presence of a catalyst such as NO₂, forms H₂SO₄, and thus acid rain.[2] This is one of the causes for concern over the environmental impact of the use of these fuels as power sources.
• Nitrogen oxides (NO_x) - especially nitrogen dioxide are emitted from high temperature combustion. Can be seen as the brown haze dome above or plume downwind of cities.Nitrogen dioxide is the chemical compound with the formula NO₂. It is one of the several nitrogen oxides. This reddish-brown toxic gas has a characteristic sharp, biting odor. NO₂ is one of the most prominent air pollutants.
• Carbon monoxide - is a colourless, odourless, non-irritating but very poisonous gas. It is a product by incomplete combustion of fuel such as natural gas, coal or wood. Vehicular exhaust is a major source of carbon monoxide.
• Carbon dioxide (CO₂) - a greenhouse gas emitted from combustion but is also a gas vital to living organisms. It is a natural gas in the atmosphere.
• Volatile organic compounds - VOCs are an important outdoor air pollutant. In this field they are often divided into the separate categories of methane (CH₄) and non-methane (NMVOCs). Methane is an extremely efficient greenhouse gas which contributes to enhanced global warming. Other hydrocarbon VOCs are also significant greenhouse gases via their role in creating ozone and in prolonging the life of methane in the atmosphere, although the effect varies depending on local air quality. Within the NMVOCs, the aromatic compounds benzene, toluene and xylene are suspected carcinogens and may lead to leukemia through prolonged exposure. 1,3-butadiene is another dangerous compound which is often associated with industrial uses.

• Particulate matter - Particulates, alternatively referred to as particulate matter (PM) or fine particles, are tiny particles of solid or liquid suspended in a gas. In contrast, aerosol refers to particles and the gas together. Sources of particulate matter can be man made or natural. Some particulates occur naturally, originating from volcanoes, dust storms, forest and grassland fires, living vegetation, and sea spray. Human activities, such as the burning of fossil fuels in vehicles, power plants and various industrial processes also generate significant amounts of aerosols. Averaged over the globe, anthropogenic aerosols—those made by human activities—currently account for about 10 percent of the total amount of aerosols in our atmosphere. Increased levels of fine particles in the air are linked to health hazards such as heart disease, altered lung function and lung cancer

Air pollution

Air pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or damages the natural environment, into the atmosphere.

The atmosphere is a complex, dynamic natural gaseous system that is essential to support life on planet Earth. Stratospheric ozone depletion due to air pollution has long been recognized as a threat to human health as well as to the Earth's ecosystems.

Accessibility

Increasingly in some countries, buses and coaches are designed with accessibility features, often in response to regulations and recommendations laid out in disability discrimination laws. While such access laws apply to public transport, accessible features are also often adopted by private operators as a customer service differentiator, or due to the accessible designs becoming the market standard for new buses and coaches.

Historically, accessible buses were specially modified standard buses, as mobility buses, produced by post manufacture, or niche manufacturers. Later, many standard bus types have become accessible, although mobility buses are still in production, usually as minibus-size vehicles. Mobility buses can be modified with a side or rear wheelchair lift, additional doors, wider doors, or an extendible access ramp. For standard buses, a major part of accessibility is achieved by the low-floor bus design, although for coaches, accessibility is being achieved through wheelchair lifts due to their higher floor level. Easier access for wheelchairs, pushchairs and the elderly can also be achieved through the use of kneeling air suspension and electrically or hydraulically extended under-floor ramps. Other accessibility features include wide entrances and interior gangways for wheelchairs and baby carriages; brightly colored interior fittings; and clear destination displays to aid the visually impaired.

Coaches

Main article: coach (vehicle)

Coaches parked at Chichen Itza, Mexico

A coach or motorcoach describes a more luxurious version of a bus, designed for more comfortable or longer-distance travel. In the UK, an old-fashioned word for it is a charabanc.

Coaches can come in the same general configurations as buses, as single- or double-deckers, articulated, or small 'mini-coaches'. Coaches have a higher floor level than buses, to let luggage be stored in compartments under the passenger floor. Larger coach designs are often heavier and have more power than buses of the same size, to let them travel at higher speeds on motorway or autoroute, and have more capacity for luggage. Coaches do not generally allow for standing passengers, and feature upholstered, high-backed, individual seats. Coaches often have passenger comforts such as reclining seats, hand luggage storage, toilets, and audio-visual entertainment systems. As a low-cost version of a coach, buses may be fitted with coach-style, higher-backed, more comfortable seats, termed 'dual-purposed' bodywork. These may be used on long-distance public transport services, or as low-cost charter coaches. Increasingly in some areas individual upholstered coach-style seating, either fully high-backed or standard bus-seat height, is being deployed on higher-specification transit buses, sometimes with leather upholstery

Articulated buses

Articulated buses take the form of single-decker bus with a 'trailer' portion attached. In articulated buses, drive can be through the front or rear section's axles. In modern articulated buses one can walk between the front and rear sections through an "accordion joint".

Volvo B10M Articulated bus in Adelaide, South Australia

In the UK they are often called bendy buses.

[edit] Low-floor buses

Main article: Low-floor bus

For many new fleets, particularly in local transit systems, there is an increasing shift to low-floor buses (primarily for easier accessibility).

High-floor buses, whose design allows for luggage compartments underneath the passenger seating area, are used for longer-distance intercity travel (see Coaches). The move to the low-floor design has all but eliminated the mid-engined design, although some coaches still have mid mounted engines.

[edit] Bi-articulated

An uncommon departure from the standard rigid or articulated buses, there also exist limited instances of bi-articulated buses, and passenger-carrying trailers— either towed behind a conventional bus (a bus trailer), or hauled as a trailer by a truck (a trailer bus).

[edit] Open top

Main article: Open top bus

A bus may be "open top", that is to say, it has little or no roof. The aim is for passengers to get a better feel for of the outdoors (for good or bad), and a better view. Typically they are used as tourist buses on short city tours. The coachbuilding is generally done when the vehicle is first made, but sometimes an open top bus is converted from a double-decker that has scraped or lost its roof on a low bridge or other impediment, since its chassis will generally be intact

Single deckers

The most common design of bus is a rigid single-decker bus with two axles, or if needed, a second rear axle. The midibus is a lighter and smaller purpose built development of the single deck bus, which emerged in the 1990s. The minibus, originally developed from van conversions, fulfills the lowest capacity needs of buses. Minibuses today are both still derived from vans, or built specifically as minibuses.

[edit] Double deckers

Main article: Double-decker bus

Where more capaciity is needed, a double-decker bus or articulated bus may be used, the prevalence of which varies from country to country. A double-decker is a rigid vehicle with an extra upper deck, the two conjoined for access by a staircase— usually in modern vehicles a spiral staircase near the front, but often at the rear on older vehicles, which may have an open platform. Larger double deckers might have both front and rear staircases.

Designs

The names of different types of bus vary around the world according to local tradition or marketing, although buses can be classified into basic types based on their general features.

Double-decker bus of Kowloon Motor Bus, Hong Kong

Since motorisation, the traditional configuration of a bus was an engine in the front and an entrance at the rear. Since the 1960s, with the transition to one man operation, buses in the developed world have taken the form of mid or rear-engined designs, with a single door at the front, or multiple doors, depending on need. Front-engined buses still persist for niche markets such as American school buses, some minibuses, and buses in less developed countries, which may be derived from truck chassis, rather than purpose built bus designs.

A bus may have an open platform so that passengers can join and alight without for the driver to open doors, but in many countries this is considered dangerous and is discouraged or indeed illegal.^{[citation needed]} On the other hand, in some countries bus use is so heavy that passengers will cling to the outside of the vehicle if it is full.^{[citation needed]}

Buses will often have a legal maximum capacity of passengers.

While most bus and coach designs will normally have two axles (or three for articulated buses), buses and coaches may often be fitted with additional axles to accommodate extra length or weight. This is common on three-axle rigid coaches. This is subject to local regulations.

History

There are indications of the first bus dating back to 1662,^[2] although serious horse drawn public transport bus services were not launched until the 1820s. Early buses were horse drawn vehicles, a combination of the hackney carriage and stagecoach concepts. From the 1830s the steam powered bus also existed. In parallel to the development of the bus, was the invention of the electric trolleybus running under a system of wires, which actually preceded, and in many urban areas outnumbered, the conventional engine powered bus. The first engine powered buses emerged along with development of the automobile. After the first engine powered bus of 1895, models expanded in the 1900s, leading to the widespread introduction of the contemporary recognisable form of full size buses from the 1950s

Etymology

Bus is a derivation of Omnibus Vehicle meaning "vehicle for all", where omnibus means "for all" in Latin (omnes meaning "all"), reflecting its early usage for public transport. When motorized transport replaced horse-drawn transport starting around 1905, a motorized omnibus was for a time sometimes called an autobus, a term still used in French and other languages, and in some varieties of English