Discrepancy with Nearby Sensor

[Shipuser]

I have just installed a new sensor in our backyard, the location is less than 1/2 mile from an existing sensor located near the main road through our town. Our sensor reads much higher than the sensor in town: currently our sensor reads 51; the sensor in town reads 17. Any explanation for this discrepancy. Should I assume my new sensor is faulty. Are there any local sources of pollutants that I should check?

[carlkidcrypto-paa]

Hi @Shipuser perhaps this will help.

@ShawnBoyle

Thanks for the post! This is certainly a sizable discrepancy, and I’d generally recommend following our sensor maintenance guide to address this. I understand that you performed a cleaning with your bike pump, but were you able to target those four collinear holes in the unit as outlined in that guide? If there hasn’t been an improvement after doing so, you can take them apart as you’ve mentioned, and that step is mentioned under the “Optional Steps” section of our maintenance guide.

If you’d prefer not to perform a deeper cleaning, a replacement is a perfectly reasonable way forward as Tinashe has mentioned above. You can of course purchase them from a third party if you’d like, though the benefit of getting replacements from us is that we test them in our facility.

Additionally, if you’d like to let us know the device ID of your sensor at contact@purpleair.com or in a direct message to me, I can take a look at its readings and apply downgrades to erroneous channels if necessary.

Happy to help with any additional questions or need for clarification on this!

From this post. Do I need to clean the sensor? - #5 by wooper

[Shipuser]

Hi, as requested I sent my device details to the contact@purpleair.com email. Have you had a chance to look at this?

[lucienve (LVE)]

It may be worth tracking how well that other sensor tracks the overall air quality in the area - sometimes people don’t remember to categorize their indoor sensors as outdoor, leading to discrepancies.

[Shipuser]

It doesn’t track well. The new sensor is consistently the highest in the area. Even though it is in the most residential area.

[viktoriyanavrotskaya]

@Shipuser

I have just installed a new sensor in our backyard, the location is less than 1/2 mile from an existing sensor located near the main road through our town. Our sensor reads much higher than the sensor in town: currently our sensor website reads 51; the sensor in town reads 17. Any explanation for this discrepancy. Should I assume my new sensor is faulty. Are there any local sources of pollutants that I should check?

A difference like that doesn’t automatically mean the new sensor is faulty. Small changes in placement, airflow, nearby traffic, heating systems, wood smoke, dust, or even a sheltered backyard location can cause very different readings. I’d compare both sensors over several days and check calibration before looking for pollution sources.