[Bumbatar]

Natural sunlight has UVC but a small amount. If the amount of UVC was that much of a problem it would kill the plants not make them stronger.

[Easy7]

In space, not in the livable atmosphere. That's why they need good UV protection in space, the uvc.

[Bumbatar]

Yeah I know UVC is bad but these lights dont have enough to damage the plants they actualy get more potent because the lights produce more UVB than UVC. If the lights had as much UVC as space has the plant would die not get more potent and smell stronger.

[Phaeton]

When using the research room for UVB intensity testing it did not really matter the source of UVB.
The exact wavelength was important, any frequency shorter than 315 nm has zero benefit and longer than 330 nm loses the enhancement.
Intensity needs to between 50 uw (microwatts) and 150 uw at the leaf surface.

UVC from the sun does not reach Earth, another name is "vacuum ultraviolet" because it cannot penetrate the atmosphere.
UVB is one third of one percent of the energy making it to ground level. UVA runs closer to seven percent.

Regular glass and plastic are UVB filters, it takes special formulation to allow UVB to pass and costs extra.
Some misunderstanding is going on about UVB filters on bulbs, Some brands use special low iron glass that allows a small amount of UV through, mostly UVA and only in tiny amounts that the meter readings indicate are too low to have any effect.
Advertising points, not growing points.

[Bumbatar]

I think Tangwena may have been talking about Halogen lights rather than CMH whatever the amount of UVA UVB or UVC they produced it was making the plants more potent and giving them more bag appeal.