Useful conversions. Pressure: 760 mmHg = 1 atm, 760 mmHg=101,325 Pa, 1000 Pa=1 kPa Other: 1000 ppm = 1 ppb K= C + 273.15 1. The National Ambient Air Quality Standard for ozone (O3) is 0.070 ppm. Convert this value to micrograms per cubic meter units at 15C and 101.325 kPa