What is PG, propylene glycol?
A chemical (anti-freeze) that is mixed with water to help inhibit the evaporation of water. (It is also thought to help promote the growth of hair if you rub it in your scalp). The theory that this chemical mixed with water will magically produce a perfect level of humidity regardless of temperature is a stretch of the imagination. Relative humidity is relative to air temperature. Since warm air holds more moisture, increasing temperature will increase relative humidity. Inhibiting the evaporation of water is contrary to the process of humidifying cigars.
