PAPR Respirators

If your workplace cannot achieve adequate control from LEV alone, or if it is not reasonably practicable to provide LEV, workers must be provided with suitable respiratory protective equipment (RPE). For example, if they're welding with LEV but not all the fume is captured you might be able to see residual uncaptured fume, or in the case of TIG welding, smell uncaptured ozone, then you're not controlling the risk and you should also provide respiratory protective equipment. 

The use of battery-powered air-fed protective equipment is required for work over the duration of an hour, with a minimum assigned protection factor of 20 (APF20)