Understanding Different PM Calibration Methods In The Dashboard

Understanding Different PM Calibration Methods

The dashboard supports several calibration modes. Each one fundamentally changes how your PM2.5 values are calculated.

1. Raw Data

• No calibration is applied.

• The monitor reports the unadjusted PM2.5 values.

2. EPA Formula

• The correction formula developed by the U.S. Environmental Protection Agency (EPA) is applied.

• Find the formula here:  AirGradient Documentation – Calibration Algorithms

3. Custom Calibration(via Raw PM2.5)

• A custom calibration directly adjusts the raw PM2.5 concentration values:
  

• If the scaling factor and offset were determined with a local reference instrument, the EPA formula does not apply.

4. Custom Calibration (via PM Count)

• A custom calibration uses the raw particle count (PM count) rather than the raw PM2.5 concentration.
  

At very low concentrations, PM count data often provides better resolution (since raw PM2.5 may already read 0; see Low Readings from PMS5003).

Note: If the scaling factor and offset were determined with a local reference instrument, the EPA formula does not apply.

5. Factory Calibration

• Calibration factors calculated at the factory via co-location with a reference instrument.

6. Special Formulas by Specific Batch

• Some Plantower sensor batches show systematic differences in raw readings at lower PM levels. In these cases, special correction formulas are applied to compensate.
  
  

• It is recommended to also apply the EPA formula on top, unless you have a reliable local reference for a custom calibration.