In this system, the Ozone concentration is measured as an amount of light energy per volume of air, from which the concentration in ppbv is deducted. Ozone concentration is determined by difference between UV absorption of the gas sample and the sample without ozone after filtration performed by a catalytic converter. Ozone Measurement Principles The ozone measurement is based on the universally known UV absorption principle, which consists in measuring UV absorption of ozone molecules.
Our question to Environnement S.A was ' How does your ozone analyser support both ppm and milligrams output? Is there any hardware difference for measurement? If not, is there any standard for the convertion?'. The O342M is both both certified by the US EPA and the EU (see specsheet), therefore able to provide measurement in both ppm and milligrams. So, we naturally targetted our question to Environnement S.A, one of the leading European enviromental equipment manufacturer, who develops its own O342M Ozone analyser (see picture on the right). The US EPA standard for Ozone is based on ppm, while the European one are based on milligrams. But is this really a problem? This is what we will be looking at in this article. What is interesting is that half of the world is using a standard based on milligrams measurement, while the rest is using ppb based measurement. Quantifying the impact of this ground level Ozone on Health is done via the Air Quality Index standard which each countries defines.
HOW TO CALCULATE PPM AND PPB SERIES
It is instead produced through a series of chemical reactions that occur in presence of nitrogen oxides, volatile organic compounds, sunlight and high temperatures, as shown on the following visual: Unlike particulate matter (PM 2.5), the ground-level Ozone is not emitted directly.
(Attribution: WMO GAW research on reactive gases ) Afternoon ground level Ozone concentration in July 2011
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