One of the pollutants was a fine particulate substance known as PM2.5, a major component of diesel exhaust which EPA had determined to be unsafe for inhalation at any level, particularly for health-impaired and elderly populations.
The Health Protection Agency said it was "seriously concerned" about the level of transmission and that unsafe sex was "the most plausible explanation" for the findings.
Separately to the privacy concerns, some health officials feared the Rapiscan 1000SP scanner, which uses low-level X-rays to generate the image viewed by screeners, might expose passengers to unsafe levels of radiation.