All I can say is to try it and see. Some people with Bronchiectasis or other lung issues are very sensitive to smells, others not so much.
What is a VOC (volatile organic compound)? Any chemical, natura or synthetic, that vaporizes easily into the air. That includes industrial compounds, natural substances (like the esters and oils in herbs, scents from flowers, cooking aromas.)

Are all VOC's bad for us? Not necessarily! My concern with vaporizers with essential oils, scented waxes, or scented candles are the OTHER things that are vaporizing and lingering in the air, not the scents themselves - impurities in the wax, possible conversion of the VOC in the carrier oils due to high temperature...the paper referenced by @scoop above seems to reinforce that idea, as heat is generally applied in gas chromatography to separate the compounds for measurement.

What do I do? I continue to use high-quality essential oils from a known source that are tested for purity - at room temperature or body temperature. If I make mixtures, I use fresh food-grade oil as the carrier and make small batches so nothing gets rancid. I clean my containers thoroughly and sanitize in the dishwasher.

I would think that using fresh herbs in a pot that reaches at least 180F would be safe as well, but as an added protection I would use boiled water or spring water.

Each of us has our own comfort level - mine may be more or less conservative than yours.