For the purpose of the offsite consequence analyses required under 40 CFR Part 68, Subpart B, there are several instances in which data gathered at a local meteorological station may be used to establish the modeling parameters of wind speed, atmospheric stability, temperature, and humidity for the stationary source. How close must a stationary source be to a weather station in order for that station's data to be applicable to the stationary source?

EPA has not set specific distance limits, but will allow owners and operators to use their best judgement to determine if the data from a weather station should reasonably apply to the stationary source. Factors such as topography and distance between the stationary source and a weather station should be taken into consideration when evaluating the applicability of the weather station's data to the stationary source.