The zeolite is reusable indefinitely, while It appears achievable that it could drop its effectiveness eventually on account of having “clogged up”. Presumably that’s what the filters are for: to keep dust, pollen, together with other substantial stuff that might clog the zeolite pores out with the zeolite tanks. The https://allhealthmarket.com/product/medical-supplies/portable-oxygen-concentrator-generator/oxygen-concentrator-machine-camping-use-oxygenator-driving-oxygen-bar-with-24-hours-battery-lasting-oxygen/