After many a year without protection and other stuff... I use oxygen at nite while sleeping now. Over the years I found out that my "O2" level is 22% below according to my 2 doctors.I know threads about this and other safety isues has been posed but I thought this needed to reiderated. Use a dust mask more often than not. I wear all the safety gear i can get now to save what i have, left. On a sidenote.... I also have sleep apnea and wear a mask at nite that my O2 connects to. It's not alot of fun wearing a mask to bed but WOW did I sleep good last nite. All in all, to all that think " it wont hurt me , I'll be fine", think twice and wear a dust mask. It's not like we can replace a lung like we can replace a filter.