| Protection level | Colour | Hazard types | Examples | Maximum use level |
|---|---|---|---|---|
| A1 |  |
Organic gases and vapours, boiling point > 65°C | Working with solvents created by varnish, paints and adhesives | 10 x WEL [half mask] 20 x WEL [full face mask] or 1000 ppm whichever is lower |
| A2 | |
As A1 | As A1 but to higher concentrations | 10 x WEL [half mask] 20 x WEL [full face mask] or 5000 ppm whichever is lower |
| A1B1E1 |  |
As A1+ inorganic gases and vapours + acid gases | As A1 + working with chlorine, bromine, hydrogen cyanide, hydrogen sulphide, hydrochloric acid and other acid gases | 10 x WEL [half mask] 20 x WEL [full face mask] or 1000 ppm whichever is lower |
| A1B1E1K1 |  |
As A1B1E1 + ammonia | As A1B1E1 + working with ammonia | 10 x WEL [half mask] 20 x WEL [full face mask] or 1000 ppm whichever is lower |
| A2B2E1 | |
As A1B1E1 | As A1B1E1 but to higher concentrations | 10 x WEL [half mask] 20 x WEL [full face mask] or 5000 ppm (A + B), 1000 ppm (E) whichever is lower |
| AX |
|
Organic vapours boiling point ≤ 65°C | Working with low-boiling vapours e.g. acetone, dichloromethane | For single use only. National legislation may limit maximum usage levels |
| Hg P3 |
|
Mercury | Working with mercury vapours | Maximum use time against mercury 50 hours. |
