This combination may be used at contaminant concentrations up to 20 times the workplace exposure limit (WEL). It protects against harmful and carcinogenic water and oil based particles as well as against radioactive particles, airborne biological agents of risk groups 2 + 3 and enzymes. The total leakage permitted by this combination is a maximum of 2%. 99.5% of contaminants are filtered out of the air. This combination is typically used for handling heavy metals, hardwood, brake dust, radioactive substances and pathogens (such as viruses, bacteria and fungal spores). It is also used for stainless steel welding.