The World Health Organization considers the safe daily level to be 25 micrograms per cubic meter.

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And from this year, new facilities are to meet the tougher international standard of 0.1 nanograms per cubic meter.

CNN: Warning -- this garbage is dangerous

It spews 500 nanograms of dioxin per cubic meter of fume, more than six times the Japanese safe level of 80 nanograms.

CNN: Warning -- this garbage is dangerous

On April 29, Lincoln Center recorded the highest daily pollen level for New York since it started tracking in 2009: 5, 093 particles per cubic meter (1, 500 is considered uncomfortable).

WSJ: Sniff, Sneeze, Blow, Wipe, Repeat

Current designs can produce two kilowatts per cubic meter of liquid reactor volume and without any drawbacks (some models produce methane as a by-product, this tech does not).

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The greater Salt Lake region had up to 130 micrograms of soot per cubic meter on Wednesday, or more than three times the federal clean-air limit, according to the U.S. Environmental Protection Agency.

NPR: Sickening Fog Settles Over Salt Lake City Area

Raun and Ensor conclude that federal air quality standards are adequate where ozone levels are concerned (at 75 parts per billion), but that lives would be saved if particulate matter standards were tightened below the current level of 35 micrograms per cubic meter of air.

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Common metrics of power density include: horsepower per cubic inch, watts per square meter and watts per kilogram.

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