Ozone is a compound that, in the upper air, the Stratosphere, actually protects us from the sun???s UV rays, but at ground-level, it???s actually a pollutant which can harm respiratory function.??? The Gas Can Exchange Event is open early for lawn and landscape professionals at 8:00 a.m. and the public is welcome between 9:00 a.m. and 2:00 p.m.