The earth's stratosphere stops any and all uvc produced by the sun before it reaches earth.
Uvc is deadly to living cells.
You are correct sir.
"The atmosphere blocks about 77% of the Sun's UV, when the Sun is highest in the sky (at zenith), with absorption increasing at shorter UV wavelengths. At ground level with the sun at zenith, sunlight is 44% visible light, 3% ultraviolet, and the remainder infrared.
[21][22] Of the ultraviolet radiation that reaches the Earth's surface, more than 95% is the longer wavelengths of UVA, with the small remainder UVB. There is essentially no UVC. "
Should have said UV-b was the culprit.
It burns us and it burns the plants.
Filtering it out increased my RSO yield ~20%with no loss in potency.
Mahalo for the correction.
Weeze