Chief among these are respiratory diseases such as pneumonia which directly affect lung damage which impacts feed conversion. Environmental stress that results from too high a relative humidity or too high an ammonia gas level can cause disease outbreaks, higher than average medication costs, higher than average mortality rates, and longer times to market. This typically happens with pigs that have some diseases already which is the majority of pigs. The ventilation system is comprised of many things to make it work efficiently. They include the proper fan sizes, controls, an insulated building, air inlets which distribute fresh air uniformly without drafts, and educated management personnel.
All pigs produce moisture when they breathe.
Fan rates need to change as the pigs grow. The winter variable speed fan needs to be protected from the wind especially at low airflows. Don't use old fans for your winter fan since that is the crucial fan that runs continuously. Try to seal any summer fan shutters and any air inlets within 10 feet of the winter fan to reduce short circuiting. This allows more heat to be sent out the winter fan so the air quality is better.