Wearing a mask while working in dusty or hazardous conditions is not pleasant. All non-powered masks restrict airflow and get uncomfortably hot with prolonged use, so I've often taken the risk of forgoing a mask. After severe allergies after a wood project, I realized my lungs were not a replaceable part and invested in Versaflo. God this is the best thing ever, a constant flow of filtered air inside the helmet maintains normal breathing effort and also keeps your head cool and the visor doesn't fog up. The air hose runs from the back of the helmet to the hip pocket, so the view is completely unobstructed. The only downside is the weight of the helmet which is worn like a hat so all the weight is on the neck muscles which can be a problem if someone has neck pain or spondylitis. Perhaps in the future 3M will come up with a design where the weight of the helmet is carried by the shoulder, making it even better.