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The concentrations of carbon dioxide in the atmosphere are expressed as parts per million by volume (abbreviated as ppmv, or ppm(v), or just ppm). To convert from the usual ppmv units to ppm mass (abbreviated as ppmm, or ppm(m)), multiply by the ratio of the molar mass of CO 2 to that of air, i.e. times 1.52 (44.01 divided by 28.96).
The term immediately dangerous to life or health (IDLH) is defined by the US National Institute for Occupational Safety and Health (NIOSH) as exposure to airborne contaminants that is "likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from such an environment." Examples include smoke or other ...
Toxic: a chemical that has a median lethal concentration (LC 50) in air of more than 200 parts per million (ppm) but not more than 2,000 parts per million by volume of gas or vapor, or more than 2 milligrams per liter but not more than 20 milligrams per liter of mist, fume or dust, when administered by continuous inhalation for 1 hour (or less if death occurs within 1 hour) to albino rats ...
Carbon dioxide is soluble in water and is found in groundwater, lakes, ice caps, and seawater. It is a trace gas in Earth's atmosphere at 421 parts per million (ppm), [a] or about 0.042% (as of May 2022) having risen from pre-industrial levels of 280 ppm or about 0.028%.
On average, exposures at 100 ppm or greater is dangerous to human health. [23] The WHO recommended levels of indoor CO exposure in 24 hours is 4 mg/m 3 . [ 24 ] Acute exposure should not exceed 10 mg/m 3 in 8 hours, 35 mg/m 3 in one hour and 100 mg/m 3 in 15 minutes.
The AEGL values describe the expected effects of inhalation exposure to certain compounds (airborne concentrations in ppm or mg/m 3). Each AEGL is determined by different levels of a compound's toxicological effects, based on the 4 Ds: detection, discomfort, disability and death. There are three levels of AEGL-values: AEGL-1, AEGL-2 and AEGL-3. [2]
Sometimes levels were a thousand times higher — measured in parts per billion rather than per trillion. And, notes Keeve Nachman, another of the Johns Hopkins researchers, ethylene oxide is only ...
The AQI level is based on the level of six atmospheric pollutants, namely sulfur dioxide (SO 2), nitrogen dioxide (NO 2), suspended particulates smaller than 10 μm in aerodynamic diameter (PM 10), [19] suspended particulates smaller than 2.5 μm in aerodynamic diameter (PM 2.5), [19] carbon monoxide (CO), and ozone (O 3) measured at the ...