Ideally, an air purifier should be equipped with computing power and high-precision sensors to record the number of purified particles each time it is used. As it continues to drop the concentration for you from several hundred ug/m3 to ten or twenty, the data for each filtered particle is accumulated, thereby reminding you to replace the filter based on its design life; this is one solution. Another feasible plan, which is simpler, is to install an additional PM2.5 sensor at the air outlet of the air purifier. When the particle concentration at the outlet is significantly higher than the factory state, it means the filter is likely exhausted and must be replaced, allowing us to feel justified in purchasing a new one.

However, neither of the above two filter replacement reminder plans is used by manufacturers. Neither low-end models nor "affordable luxury" models costing tens of thousands have this function. So, can we only replace the filter based on the manufacturer's suggestion of six months or a year, regardless of whether it is still effective or truly needs replacing?

In fact, there is a more direct method: air purifiers all come with PM2.5 detection functions. Refer to the rule: "only consider replacing the filter when the current indoor environment remains at a high concentration for a long time." Manufacturers' filter lifespans always include a safety margin. Currently, most purifier manufacturers use "adsorption filters." If a filter is used for too long, bacteria may grow, and continued use may lead to secondary environmental pollution.

Luftmy PM2.5 sensor application areas: air purifiers, air conditioners with purification functions, PM2.5 detectors, range hoods, smoke alarms, fresh air systems, dedicated PM2.5 sensors, air detectors, etc.