The purity of the oxygen coming from your oxygen concentrator is extremely important. You're counting on it to maintain a certain level of purity at a certain setting, to receive the amount of oxygen your need to stay healthy. This specific amount of oxygen was determined by your doctor, and prescribed to you, to make up for the amount of oxygen your lungs can't breathe in.
You can always check the purity to make sure you are getting the amount of oxygen you need. There are also ways to maintain and take care of your oxygen concentrator, to make sure it will continue to deliver this purity level for many years to come. If you ever start to feel worse and you know your COPD or other chronic lung disease hasn't exacerbated (flared up), it might be that your oxygen concentrators oxygen purity has gone down. This is definitely when you would want to put it to the test.
The reasons an oxygen concentrator might be filtering oxygen at a lower purity level, is because it's an older model that hasn't been properly refurbished and it's not working as well, there is a malfunction, or one of the filters hasn't been cleaned when necessary.
Check your owners manual to see if your oxygen concentrator has a gross particle filter. This is the filter that should be cleaned regularly, and replaced periodically. Follow the directions in your owners manual for how to remove, clean and replace the gross particle filter. If this filter isn't cleaned often enough, it can bring down the amount of pure oxygen that is brought into the oxygen concentrator. The ambient air has to first pass through the gross particle filter, to be cleaned of debris and dust in the air.
The inner filter and components might also need maintenanced, and that's when you should send your oxygen concentrator back in for maintenance. You won't be able to clean the inner filters or components yourself, and you will need to send it to the manufacturer, or to the store where you bought it from.
If you have a new oxygen concentrator and you are keeping up with any filter cleaning that you can do yourself, you should only have to get the oxygen purity checked once a year. Visit your doctor, who will check the purity with a device called an Oxygen Purity Analyzer. He or she can attach it to the oxygen outlet nozzle, and it will read the oxygen purity in percents.
Oxygen purity analyzers are expensive, the more affordable ones being around $200. You should go to your oxygen provider to get your new concentrator tested once a year, or every 6 months if you have a used model.