Your health and safety at work
Answer: If you must wear a respirator, your employer should provide you with the correct kind of respirator for the hazardous materials you work with. For example, if you work around lead, you should wear a cartridge respirator with filters that neutralize lead. You should be trained in the correct use of the respirator, including how to check your mask for leaks, the limitations of the respirator, etc.
Your respirator must: (1) fit well enough so that fumes or dust cannot leak in; (2) have the cartridge filters replaced when they are no longer useful you will know this when it is hard to breathe through it, or when you smell or taste the chemical through the mask; (3) be kept clean. Clean your mask daily and make sure that the straps work properly.