Jason Lunn is a 3M application engineering specialist for safety products. He oversees the training and education for a wide range of safety equipment, including respirators, for both painting professionals and DIY customers. Here, he tackles a common question from both of these audiences.

Q: How do I know when it’s time to change my respirator cartridge or filter?

A: Let’s start with particulate filters. To determine if it requires replacement, use ‘the three Ds.’ By that, I mean: ask yourself if the filter is dirty, damaged or difficult to breathe through. Whether a filter is dirty can be subjective. Some pros may change a filter with even the slightest bit of debris in it, while others may use it for much longer. The damaged part is pretty obvious. If the filter is torn or compromised in some way, throw it out. To determine if it’s difficult to breathe through, pay attention to your breathing resistance as you’re using the filter and when breathing becomes challenging, replace it. Keep in mind that how difficult it feels to breathe through the filter can vary from person to person.

There is also one caveat to the 3Ds. If you’re working with a filter for oil-based particulates, you will need to use an R- or a P-type filter. R means ‘resistant to oil’ and P stands for ‘oil-proof.’ These filters do have time limits when used in environments containing oily aerosols. It depends on the manufacturer, but 3M’s R filters can be used for up to eight hours, and the P filters up to 40 hours or 30 days, whichever comes first. That said, even with these products, you still want to keep the three Ds in mind as well.

Cartridge changes are a little more complicated. Before using a cartridge, take a look at the coating you’ll be applying, more specifically, its Safety Data Sheet (SDS). This document informs you of all the ingredients in the coating. Then, look up those ingredients in the 3M Respirator Selection Guide to see what type of cartridge is recommended. Once you’ve chosen the right cartridge, you need to determine its service life. For this, you’ll need an exposure assessment conducted by either an industrial hygienist, an insurer, or an OSHA representative. The exposure assessment helps you understand the concentration levels you’ll be dealing with on the job. With that information, you can then turn to the 3M Select and Service Life calculator, a free tool to help estimate the number of hours your specific cartridge can give you before recommended replacement.

One thing I also like to tell people is that if you’re using an organic vapor cartridge, it’s important to remember that once the package is open, the cartridge can begin adsorbing organic vapors even if you’re not actively using it. Remember to store your cartridges in a sealed container or bag when not in use to help keep them free from airborne contaminants.

While it’s important to know when to replace filters and cartridges, establishing a Respiratory Protection Program should be the first step. A good program includes many components, such as: exposure assessments; respirator selection; medical evaluations; annual fit testing, and respirator training. A Respiratory Protection Program also teaches your team why respirator protection is so important, which helps empower them to use the equipment correctly.

Learn more about 3M Reusable Respirators