For the first time, scientists measured an average concentration of atmospheric carbon dioxide of 400 parts per million in Mauna Loa, Hawaii, where the National Oceanic and Atmospheric Administration observatory is located, on Thursday.

CNN: CO2 levels hit new peak at key observatory

Before the 19th-century Industrial Revolution, the average carbon dioxide concentration worldwide was about 280 parts per million.

CNN: CO2 levels hit new peak at key observatory

The share of professional services jobs in the local economy is two and a half times the national average, the highest concentration in the country.

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The radon concentration in the average UK home is about 20 becquerels per cubic metre.

BBC: Radon