Calculating Amounts of Fume or Dust for EPCRA 311 / 312 Reporting

Facilities only have to count the amount of fume or dust given off a piece of metal, brick, or any other solid manufactured item that undergoes a modification process (i.e. cutting, welding, etc.) to determine whether the EPCRA sections 311 and 312 reporting thresholds have been reached. How is the amount of fume or dust counted?

To calculate the amount of fume or dust given off from a solid manufactured item, EPA recommends that facilities use one or more of the following methods: monitoring data, mass balance, emission factors, or engineering calculations.