the highest concentration of a specific air pollutant at a particular outdoor location, in a specified unit of time, that is not considered hazardous to humans: The ambient air standard for gas X is 3 parts per million per hour.
[ 1970-75 ]
the highest concentration of a specific air pollutant at a particular outdoor location, in a specified unit of time, that is not considered hazardous to humans: The ambient air standard for gas X is 3 parts per million per hour.
[ 1970-75 ]
Random House Webster's Unabridged English dictionary. Полный английский словарь Вебстер - Random House . 2012