When Should I Replace My Respirator Filters?
Every respirator is different. The best thing to do if you're not sure how long a filter has been being used on a specific respirator is to replace it before its next use. On the packaging of the next filter you buy, it should give you an idea of when you'll need to replace it. This time period is often measured in hours of use. For example, if you generally do 3-hour painting jobs, and the filter says it should be replaced every 30 hours of use, you would replace it after about 10 jobs. If you find yourself starting a job that lasts longer than the hours left on your filter (you can use safely use the filter for 2 more hours, but you're about to start a 3-hour job), don't take a chance on your safety! Go ahead and replace the filter.
If you ever (while wearing your respirator), feel dust when you inhale, smell the chemicals you're working around, or have trouble breathing, get out of the area and check your respirator for holes, cracks, or other damage.