PE cling film has moderate oxygen permeability and moisture permeability, which can regulate the oxygen and moisture content around the preserved products, block dust and pests, and prevent frequent gas exchange from causing damage to the cigar itself. This can indeed promote the reproduction of some anaerobic bacteria (in fact, the principle of cigar fermentation is different from that of microbial fermentation, which only refers to the environment within the membrane). What is certain is that the plastic wrap is "breathable" and the moisture in the air can penetrate into the inside and outside of the plastic wrap through the plastic wrap, but this process is very slow. In addition, I remember reading the information. Scientists have shown through experiments that if the plastic wrap is thicker, microorganisms or fungi will multiply faster. Once an anaerobic reaction occurs, fermentation will be easy. (Anaerobic environments cannot directly promote fermentation, but it’s good for eliminating clutter.) This is why some foods cannot be covered with plastic wrap, but this feature can be used to preserve cigars.