Smog in the context of Fog

Sustainable transport is transportation sustainable in terms of their social and environmental impacts. Components for evaluating sustainability include the particular vehicles used; the source of energy; and the infrastructure used to accommodate the transport (streets and roads, railways, airways, waterways and canals). Transportation sustainability is largely being measured by transportation system effectiveness and efficiency as well as the environmental and climate impacts of the system. Transport systems have significant impacts on the environment. In 2018, it contributed to around 20% of global CO₂ emissions. Greenhouse gas emissions from transport are increasing at a faster rate than any other energy using sector. A 2023 study published in Journal of Transport Geography found that shared electric bicycle systems reduce urban transport-related carbon emissions by about 108–120 grams per kilometre, particularly in non-central urban areas and when powered by low-carbon electricity sources.Road transport is also a major contributor to local air pollution and smog.

Sustainable transport systems make a positive contribution to the environmental, social and economic sustainability of the communities they serve. Transport systems exist to provide social and economic connections, and people quickly take up the opportunities offered by increased mobility, with poor households benefiting greatly from low carbon transport options. The advantages of increased mobility need to be weighed against the environmental, social and economic costs that transport systems pose. Short-term activity often promotes incremental improvement in fuel efficiency and vehicle emissions controls while long-term goals include migrating transportation from fossil-based energy to other alternatives such as renewable energy and use of other renewable resources. The entire life cycle of transport systems is subject to sustainability measurement and optimization.

Oxygen is a chemical element; it has the symbol O and its atomic number is 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and a potent oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is the most abundant element in Earth's crust, making up almost half of the Earth's crust in the form of various oxides such as water, carbon dioxide, iron oxides and silicates. It is also the third-most abundant element in the universe after hydrogen and helium.

At standard temperature and pressure, two oxygen atoms will bind covalently to form dioxygen, a colorless and odorless diatomic gas with the chemical formula O
₂. Dioxygen gas currently constitutes approximately 20.95% molar fraction of the Earth's atmosphere, though this has changed considerably over long periods of time in Earth's history. A much rarer triatomic allotrope of oxygen, ozone (O
₃), strongly absorbs the UVB and UVC wavelengths and forms a protective ozone layer at the lower stratosphere, which shields the biosphere from ionizing ultraviolet radiation. However, ozone present at the surface is a corrosive byproduct of smog and thus an air pollutant.

In economics, excludability is the degree to which a good, service or resource can be limited to only paying customers, or conversely, the degree to which a supplier, producer or other managing body (e.g. a government) can prevent consumption of a good. In economics, a good, service or resource is broadly assigned two fundamental characteristics; a degree of excludability and a degree of rivalry.

Excludability was originally proposed in 1954 by American economist Paul Samuelson where he formalised the concept now known as public goods, i.e. goods that are both non-rivalrous and non-excludable. Samuelson additionally highlighted the market failure of the free-rider problem that can occur with non-excludable goods. Samuelson's theory of good classification was then further expanded upon by Richard Musgrave in 1959, Garrett Hardin in 1968 who expanded upon another key market inefficiency of non-excludable goods; the tragedy of the commons.

In linguistics, a portmanteau or blend, also known as a blend word or lexical blend, is a word formed by combining the meanings and parts of the sounds of two or more words. English examples include smog, coined by blending smoke and fog, and motel, from motor (motorist) and hotel.

In some languages, contamination refers to a subset of blends, where the words combined are synonyms or have similar meanings. This kind of blend can be deliberate or accidental. A blend is similar to a contraction. On one hand, mainstream blends tend to be formed at a particular historical moment followed by a rapid rise in popularity. On the other hand, contractions are formed by the gradual drifting together of words over time due to the words commonly appearing together in sequence, such as do not naturally becoming don't (phonologically, /duː nɒt/ becoming /doʊnt/). A blend also differs from a compound, which fully preserves the stems of the original words. The British lecturer Valerie Adams's 1973 Introduction to Modern English Word-Formation explains that "In words such as motel..., hotel is represented by various shorter substitutes – ‑otel... – which I shall call splinters. Words containing splinters I shall call blends". Thus, at least one of the parts of a blend, strictly speaking, is not a complete morpheme, but instead a mere splinter or leftover word fragment. For instance, starfish is a compound, not a blend, of star and fish, as it includes both words in full. However, if it were called a "stish" or a "starsh", it would be a blend. Furthermore, when blends are formed by shortening established compounds or phrases, they can be considered clipped compounds, such as romcom for romantic comedy.

In atmospheric chemistry, NO_x is shorthand for nitric oxide (NO) and nitrogen dioxide (NO₂), the nitrogen oxides that are most relevant for air pollution. These gases contribute to the formation of smog and acid rain, as well as affecting tropospheric ozone.

NO_x gases are usually produced from the reaction between nitrogen and oxygen during combustion of fuels, such as hydrocarbons, in air; especially at high temperatures, such as in car engines. In areas of high motor vehicle traffic, such as in large cities, the nitrogen oxides emitted can be a significant source of air pollution. NO_x gases are also produced naturally by lightning.

A marine layer is an air mass that develops over the surface of a large body of water, such as an ocean or large lake, in the presence of a temperature inversion. The inversion itself is usually initiated by the cooling effect caused when cold water on the surface of the ocean interacts with a comparatively warm air mass.

In meteorology, an inversion (or temperature inversion) is a phenomenon in which a layer of warmer air overlies cooler air. Normally, air temperature gradually decreases as altitude increases, but this relationship is reversed in an inversion.

An inversion traps air pollution, such as smog, near the ground. An inversion can also suppress convection by acting as a "cap". If this cap is broken for any of several reasons, convection of any humidity can then erupt into violent thunderstorms. Temperature inversion can cause freezing rain in cold climates.

Vog is a form of air pollution that results when sulfur dioxide and other gases and particles emitted by an erupting volcano react with oxygen and moisture in the presence of sunlight. The word is a portmanteau of the words "volcanic" and "smog," the latter itself a portmanteau of "smoke" and "fog." The term is in common use in the Hawaiian Islands, where the Kīlauea volcano, on the Island of Hawaiʻi (the "Big Island"), erupted continuously between 1983 and 2018. Based on June 2008 measurements, Kīlauea emits 2,000–4,000 tons of sulfur dioxide (SO₂) every day.

Ethyl tertiary-butyl ether (ETBE), also known as ethyl tert-butyl ether, is commonly used as an oxygenate gasoline additive in the production of gasoline from crude oil. ETBE offers equal or greater air quality benefits than ethanol, while being technically and logistically less challenging. Unlike ethanol, ETBE does not induce evaporation of gasoline, which is one of the causes of smog, and does not absorb moisture from the atmosphere.

Atmospheric optics is "the study of the optical characteristics of the atmosphere or products of atmospheric processes .... [including] temporal and spatial resolutions beyond those discernible with the naked eye". Meteorological optics is "that part of atmospheric optics concerned with the study of patterns observable with the naked eye". Nevertheless, the two terms are sometimes used interchangeably.

Meteorological optical phenomena, as described in this article, are concerned with how the optical properties of Earth's atmosphere cause a wide range of optical phenomena and visual perception phenomena.Examples of meteorological phenomena include:

The health and environmental impact of transport is significant because transport burns most of the world's petroleum. This causes illness and deaths from air pollution, including nitrous oxides and particulates, and is a significant cause of climate change through emission of carbon dioxide. Within the transport sector, road transport is the largest contributor to climate change.

Environmental regulations in developed countries have reduced the individual vehicle's emission.However, this has been offset by an increase in the number of vehicles, and increased use of each vehicle (an effect known as the Jevons paradox).Some pathways to reduce the carbon emissions of road vehicles have been considerably studied.Energy use and emissions vary largely between modes, causing environmentalists to call for a transition from air and road to rail and human-powered transport, and increase transport electrification and energy efficiency.

Pea soup fog (also known as a pea souper, black fog or killer fog) is a very thick and often greenish-yellow fog caused by air pollution that contains tarry soot particulates and the poisonous gas sulphur dioxide. This very thick smog occurs in cities and is derived from the smoke given off by the burning of soft coal for home heating and in industrial processes. Smog of this intensity is often lethal to vulnerable people such as the elderly, infants, and those with respiratory problems. The result of these phenomena was commonly known as a London particular or London fog; in a reversal of the idiom, "London particular" became the name for a thick pea and ham soup.

Hermosa Beach (Hermosa, Spanish for "Beautiful") is a beachfront city in Los Angeles County, California, United States. Its population was 19,728 at the 2020 U.S. census. The city is located in the South Bay region of the Greater Los Angeles area; it is one of the three Beach Cities. Hermosa Beach is bordered by the other two, Manhattan Beach to the north and Redondo Beach to the south and east.

The city's beach is popular for sunbathing, beach volleyball, surfing, paddleboarding, bars, cycling and running. The city itself extends only about 15 blocks from east to west and 40 blocks from north to south, with Pacific Coast Highway running down the middle. Situated on the Pacific Ocean, Hermosa's average temperature is 70 °F (21 °C) in the summer and 55 °F (13 °C) in the winter. Westerly sea breezes lessen what can be high summertime temperatures in Los Angeles and elsewhere in the county and help keep the smog away 360 days of the year.

In chemistry, a photoinitiator is a molecule that creates reactive species (free radicals, cations or anions) when exposed to radiation (UV or visible). Synthetic photoinitiators are key components in photopolymers (for example, photo-curable coatings, adhesives and dental restoratives).

Some small molecules in the atmosphere can also act as photoinitiators by decomposing to give free radicals (in photochemical smog). For instance, nitrogen dioxide (NO₂) is produced in large quantities by gasoline-burning internal combustion engines. NO₂ in the troposphere gives smog its brown coloration and catalyzes production of toxic ground-level ozone (O₃). Molecular oxygen (O₂) also serves as a photoinitiator in the stratosphere, breaking down into atomic oxygen and combining with O₂ in order to form the ozone in the ozone layer.