What is a significant risk factor for infections during shaving?

Using dull blades is a significant risk factor for infections during shaving because dull blades can cause more irritation and micro-abrasions on the skin. When a blade is not sharp, it struggles to cut hair effectively and may tear at the skin instead, leading to small nicks and cuts. These minor injuries can provide an entry point for bacteria and other pathogens, increasing the risk of infection.

Sharp blades, on the other hand, create a cleaner cut, reducing trauma to the skin. Applying excess pressure can also lead to irritation and cuts, but the quality of the blade plays a more critical role in the overall risk of infection. Finally, using non-sterile tools can pose a significant risk to sanitation and hygiene, contributing to potential infections; however, within the context of this question, the dull blade's contribution to skin injury and subsequent infection risk is particularly noteworthy.