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14 godz. temu · Average levels of PM 2.5 were measured using aqicn.org's World Air Quality Index data, and a formula developed by AirNow was used to convert the PM 2.5 figure into micrograms per cubic meter of air (μg / m 3) values. Among the 70 capital cities investigated, Baghdad, Iraq is the worst performing one, with PM 2.5 levels going up +31.6 μg / m 3.
14 godz. temu · 10 −5: Platinum–iridium bar at melting point of ice (1st CGPM) 1889 0.2–0.1 μm: 10 −7: Platinum–iridium bar at melting point of ice, atmospheric pressure, supported by two rollers (7th CGPM) 1927 n.a. n.a. Hyperfine atomic transition; 1 650 763.73 wavelengths of light from a specified transition in krypton-86 (11th CGPM) 1960 4 nm: 4 ...
