Inhalation Dose

Integrate retained inhaled mass across measured concentration/ventilation/exposure intervals; respiratory deposition fractions are supplied, not inferred from particle size.

Description

Calculate retained inhaled mass for exposure intervals and divide the total by body mass.

Inhalation exposure connects an air concentration with the volume breathed during exposure. A supplied retained fraction then describes the part assumed retained under the model. A retained mass estimate is distinct from an air-concentration benchmark used in an inhalation risk assessment.^[1]

This tool treats concentration, ventilation, and retained fraction as constant within each interval. It multiplies mg/m³ by m³/hour, hours, and a dimensionless fraction to obtain retained mg, then divides the total by body mass in kg.

The final output is an amount in mg/kg over the supplied intervals. It is not automatically mg/kg/day, a lung-tissue concentration, or an exposure concentration suitable for direct comparison with an RfC.

When to use Inhalation Dose

Use it to reconcile an interval-based inhalation mass calculation or compare specified breathing-rate and retention assumptions.

How to use Inhalation Dose and interpret its calculation

Enter aligned, nonempty concentrationsMgPerCubicMeter, ventilationCubicMetersPerHour, exposureHours, and retainedFractions lists.
Use nonnegative concentrations, ventilation, and durations, retained fractions between 0 and 1, and a positive bodyMassKg.
Run the calculation and read retainedMassesMg for each interval and retainedDoseMgPerKg for the total. Keep the exposure interval and retention definition explicit.

mass_i = C_i × ventilation_i × hours_i × retained fraction_i; retained dose = Σ mass_i / body mass

Ventilation is breathed volume per hour, not body-mass-normalized ventilation or a daily rate.

The implementation uses paired interval products and a total mass sum. It does not interpolate concentration logs, retrieve ventilation or retention values, or divide by a daily averaging duration.

json

{
  "input": {
    "concentrationsMgPerCubicMeter": [
      1,
      2
    ],
    "ventilationCubicMetersPerHour": [
      1,
      0.5
    ],
    "exposureHours": [
      2,
      2
    ],
    "retainedFractions": [
      0.5,
      0.5
    ],
    "bodyMassKg": 50
  },
  "output": {
    "retainedMassesMg": [
      1,
      1
    ],
    "retainedDoseMgPerKg": 0.04
  }
}

Zero concentration, ventilation, duration, or retained fraction makes that interval contribute zero. An all-zero exposure is accepted. A zero body mass, negative interval value, fraction outside 0–1, or mismatched list is rejected.

Limitations and assumptions

No regional respiratory deposition, particle-size distribution, gas exchange, clearance, absorption kinetics, exercise schedule, or biological effect is inferred. Retention must be defined consistently for the intended scenario.

An mg/kg amount cannot directly be compared with an mg/m³ RfC. The tool does not perform continuous-concentration adjustment or retrieve an inhalation benchmark.

Alternative or Complementary methods

Use concentration-based assessment methods when the benchmark is an RfC. A concentration-time integral describes another exposure summary, while aggregation across routes requires compatible time and absorbed-dose definitions.

References

Exposure Assessment Tools by Routes — Inhalation — U.S. Environmental Protection Agency

Similar or alternative tools

Reference Concentration
Apply supplied schedule, dosimetric adjustment, and factors to an inhalation point of departure.
Haber Time Scaling
Sum concentration-times-duration without ventilation or retention weighting.