anchor: The SUM06 is the sum of the ozone concentrations for every hour that exceeds 0.06 parts per million (ppm) within a 12-hour period from 8 am to 8 pm in the months of May to September.
positive: The SUM06 is the sum of the ozone concentrations for every hour that exceeds 0.06 parts per million.
negative: The SUM06 is the sum of the ozone concentrations for every hour that exceeds 0.78 parts per million.