Aaron, the SD data is uncorrected and unmodified in all cases. API data is also not corrected in any way, so you will get what the sensor sent with no conversions or corrections applied. On exception is the CF=3 field.
Aaron and Adrian–
If I am understanding what Aaron is saying, this is bad news for people wanting to use the PurpleAir data. The “new” 5003 makes a completely arbitrary change to the >0.3 um/dl, dropping it down by a huge margin. This affects the ALT-CF3 data in one major way: it reduces the contribution of the 0.3-0.5 um/dl (which you get by subtracting the >0.5 u/dl from the >0.3 um/dl) from typically about 16% of the total PM2.5 value to < 1%!. I have been running two “new” 5003s side by side with three “old” 5003s for a couple of months now. But it did not take long to see the effect.
Adrian, do you think this change will be permanent? If so, we would need a marker to identify the “new” 5003s. It may be time to look for an alternate sensor.
This change with the 5003 laser counters is not permanent. We received a batch of laser counters with this issue, but the ones we are receiving and sending out now are the standard ones we were using previously. We check all laser counters for this issue before they are sent out.
Thanks, Ethan for that news. I feel better.
Good news that this is a temporary problem. It would be really great if there were a way of ordering sensors directly from PurpleAir in countries other than the US (e.g. in Europe). I know it’s possible but the customs and shipping costs make ordering sensors prohibitive for non-US based customers.