The following letter concerns FCC RFR rule violation notices to the Mt. Wilson broadcasters noted in CGC #598 & 600.

Ric Tell writes on October 28, 2003:

I thought that I would comment on the recently released Notice of Apparent Liability (NAL) to four broadcasters at Mt. Wilson (see CGC #600).

The most important take-home message I get from the NAL is the expectation, essentially a requirement, of complete cooperation among users at multiuser transmitter sites relative to RF safety issues!  For example, even those licensees who only contribute to the aggregate RF fields that exceed the MPE limit at a site in a relatively minor way, but above the 5% of MPE limit, must take whatever action is necessary to protect themselves from fines for violating the FCC RF rules.  This is because the FCC expects the site to comply, not just individual licensees.  And, this is likely some form of cooperative action with other users at the site to mitigate potential exposures that could include:

1. access restriction (installation of barriers);
2. installation of appropriate signage;
3. implementing RF safety training of persons on site;
4. use of protective clothing where applicable;
5. use of RF personal monitors when applicable;
6. instigation of specific work practices that will reduce exposures (for example, an RF safety plan for climbing towers);
and, even, if necessary, the last resort of
7. engineering changes to the site.

This all boils down to all site users being involved in an RF safety program for the site that ensures that no one will be exposed beyond the applicable RF exposure limits, whether it be members of the public in uncontrolled areas or workers in controlled areas.  The NAL shows us that the FCC expects even minor contributors to areas exceeding the MPE limits to be just as responsible as those who are major contributors!  Hence, if a site user, such as a rooftop wireless telecommunications carrier is causing a noncompliance problem at a site, or the site is out of spec due to the combined fields of several users, and other collocated carriers can exceed the 5% of MPE threshold established by the FCC, then everyone needs to work to force the implementation of whatever is necessary to correct this problem.  Otherwise, they may also be drug into the issue when and if the FCC inspects the site and determines that the public or workers can be exposed beyond the applicable limits.  In a scenario where site users are unwilling to cooperate, it could mean that minor contributors and/or the newest tenant at the site will have to bear the cost of signage or be responsible for controlling physical access to high field areas, etc., if they want to avoid fines.

In summary:

The site, taking into account the combined RF fields of all site users, has to be compliant with the FCC exposure limits;
Even 5% of MPE contributors must take aggressive action when combined fields exceed the MPE limits to make sure that the combined operations of all users at the site will comply; Many of these responsibilities may be borne by the "new kid on the block" even if they are minor contributors IF other site users won't work cooperatively.

While these insights may, at first, seem to be an over-reaction, they appear to be supported by the recent NAL.

Ric Tell, K5UJU, rtell@radhaz.com