However, given the high winds on the evening of the release, and our estimate that 99% of the release happened over a 7 minute period (more on the later in a follow on report), it is plausible that there was only a narrow cone shaped area of possible exposure which extended North West from the exhaust stack. Hence, employee's testing negative is believable good news.
People in the direct line of this exhaust path would be at risk, as would anyone in a building that had an air intake in that path. But there is at least one person of special interest who may have had significant exposure, the person whose job it was to go outside and manually activate the HEPA filter system.
Lets just hope there is no follow on info which draws things into question again.