In the case of infusion, you only have vacuum exhaust and outgassing while pulling the resin into the layers of fibers. This is done in a short time, from then on you only maintain the vacuum, and the amount of outgassing is very, very, small as long as you have a good airseal. A very tight vacumbag is a necessity when using infusion, otherwise you get faults in the laminate. It is therefore standard procedure to check the vacumbags integrity before you pull the resin in.

On the topic of laminating by hand.. A skilled worker can achieve about the same resin/fiber ratios as a wet layup with vacuum, but he uses more time and is exposed to the fumes and chemicals for a longer time. I am not certain infusion results in stronger/lighter parts when compared to wet layup with vacuum. I think infusion uses more resin to fill all voids in the foam surface, but have not had the opportunity to compare weights.