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Smog, or smoke fog, is a type of intense air pollution. The word "smog" was coined in the early 20th century, and is a portmanteau of the words smoke and fog [ 1 ] to refer to smoky fog due to its opacity, and odour. [ 2 ]
In the air, the condensed water is called either fog or a cloud, depending on its altitude when it forms. If the temperature is below the dew point, and no dew or fog forms, the vapor is called supersaturated. This can happen if there are not enough particles in the air to act as condensation nuclei. [8]
Fog is a visible aerosol consisting of tiny water droplets or ice crystals suspended in the air at or near the Earth's surface. [1] [2] Fog can be considered a type of low-lying cloud usually resembling stratus and is heavily influenced by nearby bodies of water, topography, and wind conditions.
In this test chamber, air pressure drops suddenly to that of the atmosphere at 60,000 ft (18,000 m). Air humidity immediately condenses into fog, which within seconds evaporates back into gas. The term uncontrolled decompression here refers to the unplanned depressurisation of vessels that are occupied by people; for example, a pressurised ...
A concentration of just 23.5% oxygen, or roughly 2.5% above normal oxygen levels, can create an immediately hazardous condition due to the flammable nature of oxygen enriched environments.
The limiting oxygen concentration (LOC), [1] also known as the minimum oxygen concentration (MOC), [2] is defined as the limiting concentration of oxygen below which combustion is not possible, independent of the concentration of fuel. It is expressed in units of volume percent of oxygen. The LOC varies with pressure and temperature.
At very high altitude, from 3,500 to 5,500 metres (11,500 to 18,000 ft) arterial oxygen saturation falls below 90% and arterial P O 2 is reduced to the extent that extreme hypoxemia may occur during exercise and sleep, and if high altitude pulmonary edema occurs. In this range severe altitude illness is common. [2]
Sudden drop in ambient pressure during an ascent to the surface from a 6 m final stop on oxygen. A shift from breathing oxygen at the final 6 m decompression stop at a partial pressure of 1.6 bar to breathing air at the surface with a partial pressure of 0.2 bar, could have vasodilatory effects during the period directly after surfacing.