(VCCEP) Tier 1 Pilot Submission for BENZENE - Tera

The data used to represent typical urban and rural concentrations are presented on Table 7.6a.
These values were obtained from the 1996 NATA data. The data used to represent the urban
and rural high-end exposure concentrations are presented on Table 7.6b. The 2003 urban
value is from 2000 AirData. Because there were no rural data near the top five rural sources in
2003 AirData, the rural value is from 2000 AirData.
Benzene VCCEP Submission
March 2006
Table 7.6a: Representative Typical Ambient Air Benzene
Concentrations in Rural and Urban Areas
Setting
Typical Exposure
Concentration (µg/m 3 ) Description
Rural 0.72 1996 NATA mean of “all rural”
data
Urban 1.57 1996 NATA mean of “all urban”
data
Table 7.6b: Representative High-End Ambient Air Benzene
Concentrations in Areas of Industrial Releases
Setting
High-End Exposure
Concentration (µg/m 3 ) Description
Rural 1.0 2000 AirData; Rural mean
concentration
Urban 4.4 2003 AirData; mean
concentration at the monitoring
station closest to highest urban
TRI emitter (Harris County, TX)
The typical and high-end exposure concentrations listed above were used to calculate benzene
intakes from exposure to outdoor ambient air. Exposure was quantified for residents living in
urban and rural settings according to the following equation:
where:
C × ED × EF × ET × IR × ABSi × CF
ADD =
BW × AT
ADD = average daily dose (mg/kg-day)
C = concentration of benzene in ambient air (µg/m 3 )
ED = exposure duration (years)
EF = exposure frequency (days/year)
ET = exposure time (hours/day)
CF = conversion factor (0.001 mg/µg)
ABSi = benzene inhalation absorption factor; 0.5 (unitless)
IR = inhalation rate (m 3 /hour)
BW = body weight (kg)
AT = averaging time (days)
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