Q: Why is there a gap in the channel readings?

A: When looking at the map graph, there may be a channel reading slightly lower or slightly higher than the other channel, but the pattern of the reading is similar.

This can be typical in low-cost sensors, particularly with lower readings. We use the average between the two channels to determine the AQI and confidence score. If the sensor is comparable to nearby sensors on the map and the confidence score is at 85% or higher, your sensor should be reading accurately.

Other factors can be sensor age or contamination in one channel or the other. The laser counters have an average lifespan of about two years but can last a lot longer (or shorter) depending on the conditions under which they operate.

If one channel is reading abnormally high, the confidence score is low, or a channel has been downgraded, we recommend reading through our Sensor Maintenance article.

I’ve realized the differences on my PA-II vary only at very low concentrations otherwise they match perfectly. I’ve decided not to worry about it.