Tobacco leaves, cut tobacco and paper are all extremely hygroscopic which means tha they give up their moisture to the surrounding environment if the air is too dry.
Tobacco is a plant with a high moisture content , which releases moisture into the environment when the surrounding air is too dry. Dry air causes the leaves to shrink, leading to weight loss, increased fragility , cracks and tears. These adversely affect the production process, causing the tobacco to come out of the cigarettes , wrapping paper to get caught in the machinery and tobacco leaves used in cigar production breaks. Maintaining the right level of ambient relative humidity prevents all these problems by ensuring that tobacco, paper and leaves retain moisture at the correct levels, so maintaining their quality and ensuring that production can proceed at full efficiency. In order to maintain the tobacco at desired moisture content , different conditions of humidity and temperatures are required to be maintained in specific production stages or during storage.
Considering cigarettes, for example, the moisture content may vary by up to 12% in weight when the humidity of the surrounding air varies in the range from 40% to 70% r.H. (at 24 °C).