The cannabis plants also emit toxins through their leaves and this is important for the healthy development of the plant.  They are unable to do this when the room is extremely humid, which instead causes the leaves to grow wide and there will be a reduction in the amount of resin will be produced.  It is important not to let the room become too warm in a growing area with too little humidity, this will cause the plants foliage and buds to brown. This occurs because the roots are not able to get water to the foliage fast enough in a room dry room with high heat.