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OSHA requires employers who send workers into areas where the oxygen concentration is known or expected to be less than 19.5% to follow the provision of the Respiratory Protection Standard [29 CFR 1910.134]. Generally, work in an oxygen depleted environment requires an SCBA or airline respirator.
The OSHA definition is arguably broad enough to include oxygen-deficient circumstances in the absence of "airborne contaminants", as well as many other chemical, thermal, or pneumatic hazards to life or health (e.g., pure helium, super-cooled or super-heated air, hyperbaric or hypo-baric or submerged chambers, etc.).
Nitrogen is the most common pure element in the earth, making up 78.1% of the volume of the atmosphere [9] (75.5% by mass), around 3.89 million gigatonnes (3.89 × 10 18 kg). Despite this, it is not very abundant in Earth's crust, making up somewhere around 19 parts per million of this, on par with niobium, gallium, and lithium.
Many organisms require hypoxic conditions. Oxygen is poisonous to anaerobic bacteria for example. [3] Oxygen depletion is typically expressed as a percentage of the oxygen that would dissolve in the water at the prevailing temperature and salinity. A system with low concentration—in the range between 1 and 30% saturation—is called hypoxic ...
Pressurized aircraft cabins are typically maintained at 75 kPa, the pressure found at 2,500 m (8,200 ft) altitude, resulting in an oxygen partial pressure of about 16 kPa, which is the same as a 15% oxygen concentration in a hypoxic-air application at sea-level pressure. However, passengers are sedentary and crew members have immediate access ...
The entire ocean, containing 97% of Earth's water, spans 70.8% of Earth's surface, [8] making it Earth's global ocean or world ocean. [ 23 ] [ 25 ] This makes Earth, along with its vibrant hydrosphere a "water world" [ 43 ] [ 44 ] or " ocean world ", [ 45 ] [ 46 ] particularly in Earth's early history when the ocean is thought to have possibly ...
The expected changes in radial velocity are very small – Jupiter causes the Sun to change velocity by about 12.4 m/s over a period of 12 years, and the Earth's effect is only 0.1 m/s over a period of 1 year – so long-term observations by instruments with a very high resolution are required.