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Calcimator

Emission Rate Calculator

Calculate source emission rate from measured indoor concentration, ventilation rate, and room volume.

Inputs

Results

Emission Rate (μg/hr)

7,645.5

Emission Rate (mg/hr)7.65
Source Strength (μg/m³·hr)179.98
Steady-State Conc. (μg/m³)45
Time to 90% Steady State (min)34.5
Air Exchange Rate (1/hr)4
How to Use This Calculator
  1. Enter Measured Concentration (μg/m³), Ventilation Rate (CFM), and Room Volume (ft³).
  2. Set Background Concentration (μg/m³).
  3. Review the Emission Rate (μg/hr) result.
  4. Use Emission Rate (mg/hr) and Source Strength (μg/m³·hr) to inform your decision.

How the result changes with Measured Concentration (μg/m³)

Measured Concentration (μg/m³)Emission Rate (μg/hr)
10,0001,698,150.5
35,0005,945,650.5
65,00011,042,650.5
90,00015,290,150.5

What each input means

Measured Concentration (μg/m³)
Measured indoor pollutant concentration at steady state in micrograms per cubic meter.
Ventilation Rate (CFM)
Total outdoor air ventilation rate in cubic feet per minute.
Room Volume (ft³)
Total room volume (length × width × height) in cubic feet.
Background Concentration (μg/m³)
Outdoor or supply air background concentration of the pollutant.

What each result means

Emission Rate (μg/hr)
Calculated pollutant emission rate from the indoor source.
Emission Rate (mg/hr)
Emission rate converted to milligrams per hour.
Source Strength (μg/m³·hr)
Emission rate normalized to room volume.
Steady-State Conc. (μg/m³)
Verification: steady-state concentration from computed emission rate.
Time to 90% Steady State (min)
Approximate time for the room to reach 90% of steady-state concentration.
Air Exchange Rate (1/hr)
Number of room volumes of outdoor air per hour.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Measured Concentration (μg/m³) = 50, Ventilation Rate (CFM) = 100, Room Volume (ft³) = 1500, Background Concentration (μg/m³) = 5 = 4 input(s) provided
  2. Calculate Emission Rate
    Emission Rate = netConcentration * ventilationM3Hr
    7645.5 = 7645.5
  3. Calculate Emission Rate
    Emission Rate = emissionRateUgHr / 1000
    7.646 = 7.646
  4. Calculate Source Strength
    Source Strength = emissionRateUgHr / roomVolumeM3
    179.98 = 179.98

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