For the API History Field descriptions, what is the difference between PM2.5_alt and PM2.5_atm? I want to download data from my sensor and I am not sure which one to use.

PM2.5_alt vs. PM2.5_atm

Kieran (Kieran Berryman) March 22, 2024, 4:31pm 2

You’ll want to check out this community article: What is the Difference Between CF=1, ATM, and ALT?

Topic		Replies	Views
PM2.5 algorithms Data	5	1488	March 27, 2023
What is the Difference Between CF=1, ATM, and ALT? API	23	7316	March 22, 2025
How to calculate Raw PM2.5 ALT cf=3.4 from SD card files Data	3	234	November 6, 2025
Contradictory cf Information in API Docs API	1	93	June 17, 2025
Inquiry Regarding Use of PM2.5-ATM Data for Research and Policy	4	95	April 25, 2025