Sensor Maintenance

Once your sensor has been in service at the installation location, it becomes exposed to foreign contaminants. We expect the sensor to contact airborne particulate matter. But undesirable contaminants may impede the function of the sensor.

We do not recommend a regular cleaning schedule for PurpleAir sensors, and no preventive maintenance is required. If one of the laser counters is not reporting as expected, is downgraded, reporting high, not working, or spikes erratically, then it is possible that one of the laser counters in your sensor has become congested with debris, an insect, or a spider.

If necessary, clean out the laser counters: place a shop vacuum or traditional vacuum hose on the bottom of the sensor for 2-3 minutes. Clear out the laser counter with canned compressed air if further cleaning is necessary. For PA-II and PA-II-SD sensors, focus on the four collinear holes on each laser counter. For PA-I edition sensors, focus on the rectangular hole on the side opposite the fan. For the PA-II-FLEX, focus on the rounded rectangular hole on each laser counter.

For PA-II edition sensors, the A channel is the laser counter farthest from the USB port. The B channel is the laser counter closest to the USB port.

Note that an increased airflow speed can cause the fan to spin at a much higher rate and possibly damage the laser counter.

If attempts to clean the device prove unsuccessful, the laser counters in your device may need replacing. Laser counters are purchasable through our online store. Make sure to select the correct version of laser counters for your device. The laser counters for PA-II edition sensors come in a pair, while the PA-I-Indoor laser counter comes individually. All Plantower laser counters are pre-tested in PurpleAir test chambers before being sold.

The following videos will guide you on completing the laser counter replacement processes:

The PA-II “older model” has clear white tape that holds the BME280 and power adapter. The PA-II “newer model” uses 3D printed plastic pieces attached to the laser counters.