2.18 AIR INHALATION
Pollutants released and transported in the atmosphere
are subject to inhalation by people in the site region. The atmospheric
transport component provides pollutant air concentrations at selected locations
throughout the region within 50 miles of the release site. These air concentrations
are used to calculate intake via inhalation by individuals and the population.
- Transport Medium:
- air concentration at selected locations in the region about the release site, Cari, pCi/L or mg/L, expressed as a 70-year average value
- Special Process:
- none (the transport component accounts for special processes during downwind transport)
- Exposure Factors:
- inhalation rate and exposure duration.
The air concentration is used to estimate the average
daily dose for the air inhalation pathway for atmospheric transport, as
follows, for chemical pollutants:
(99)
where
Daii = average daily inhalation dose from chemical pollutant i for the air inhalation pathway (mg/kg/d)
Cari = concentration of pollutant i in air at the point of inhalation (mg/m3)
Uai = inhalation rate (m3/d)
Fai = fraction of days per year that inhalation exposure occurs (dimensionless)
EDai = exposure duration for the air inhalation pathway (yr)
BWai = body weight of individuals exposed via the air inhalation pathway (kg)
ATaii = averaging time for air inhalation exposure to pollutant i (yr).
The averaging time for noncarcinogenic chemicals is set to the exposure duration, and the averaging time for carcinogenic chemicals is fixed at 70 years.
For radionuclide pollutants, the total lifetime dose
is evaluated as follows, using the dose conversion factor to convert from
intake to dose (rem):
(100)
where
Daii = total lifetime inhalation dose from radionuclide i for the air inhalation pathway (rem)
Cari = concentration of radionuclide i in air at the point of inhalation (pCi/m3)
DFhi = dose conversion factor for inhalation of radionuclide i (rem/pCi inhaled)
and other terms are as previously defined.