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In June to August, photochemical ozone production causes very high concentrations over the East Coast of the US and China. Ground-level ozone ( O 3 ), also known as surface-level ozone and tropospheric ozone , is a trace gas in the troposphere (the lowest level of the Earth's atmosphere ), with an average concentration of 20–30 parts per ...
The reactivity of ozone makes ozone a very general agent for killing pathogens given high enough concentration and time. When used in medical treatments the efficient targeting of ozone to the site where it needs to be active is therefor important. Non-targeted ozone at high concentrations could cause unwanted damage to healthy tissues.
However, even in this "layer", the ozone concentrations are only two to eight parts per million, so most of the oxygen there is dioxygen, O 2, at about 210,000 parts per million by volume. [53] Ozone in the stratosphere is mostly produced from short-wave ultraviolet rays between 240 and 160 nm.
About 90% of the ozone in the atmosphere is contained in the stratosphere. Ozone concentrations are greatest between about 20 and 40 kilometres (66,000 and 131,000 ft), where they range from about 2 to 8 parts per million. If all of the ozone were compressed to the pressure of the air at sea level, it would be only 3 millimetres (1 ⁄ 8 inch ...
The Dobson unit (DU) is a unit of measurement of the amount of a trace gas in a vertical column through the Earth's atmosphere.It originated by, and continues to be primarily used in respect to, the study of atmospheric ozone, whose total column amount, usually termed "total ozone", and sometimes "column abundance", is dominated by the high concentrations of ozone in the stratospheric ozone layer.
The directive on 'ozone in ambient air' came into force in 2002. The long-term objective is to limit the number of days with average ozone concentrations above 120 μg/m 3 to less than 25 days a year (see table below). The objectives of the directive are in line with the World Health Organization's guidelines for ozone.
Ozone concentrations in the lower stratosphere over Antarctica increased by 5–10 percent by 2020 and will return to pre-1980 levels by about 2060–2075. This is 10–25 years later than predicted in earlier assessments, because of revised estimates of atmospheric concentrations of ozone-depleting substances, including a larger predicted ...
The index is based on the concentrations of five pollutants. The index is calculated from the concentrations of the following pollutants: ozone, nitrogen dioxide, sulfur ioxide, PM2.5 and PM10. The breakpoints between index values are defined for each pollutant separately and the overall index is defined as the maximum value of the index.