> hotter they will be," said Mr. Wessel, who expects some to exceed <br />> the thermal level within a year. Richard <br />> Tell, a Nevada engineer, also expects some emissions to rise. At <br />> more than 1,000 sites nationally, he found roughly one in 10 out <br />> of compliance, similar to Mr. Wessel's conclusion. Some are <br />> hidden or disguised for aesthetic reasons. "I've been on rooftops <br />> looking for antennas and couldn't find them because they were <br />> hidden in fake concrete blocks that were really foam," he said. <br />> Daniel Ranahan, <br />> a Lowell, Mass., <br />> roofer, said antennas are slowing jobs. "There's <br />> no mechanism for the worker to know what buildings are safe," he <br />> said. Peter <br />> Chaney, <br />> the director of safety <br />> and health for the Mechanical Contractors Association of America, <br />> which represents companies with more than 270,000 workers, in <br />> August asked the FCC to create a database of cellular antennas. <br />> One company, RF Check, in San Diego, has designed a protocol but <br />> requires collaboration from carriers and funding from phone <br />> customers. Mr. Chaney is developing a training video and brochure <br />> on RF safety to distribute to the association's members next <br />> year. "We <br />> want workers to know that the antennas are there and that there <br />> may be a <br />> potential hazard," he said. "I'm concerned about the chronic <br />> effect of this. If guys have 30-year careers and they're exposed <br />> to these things on a, regular basis?is there any long-term <br />> effect?" The <br />> National Institute for Occupational Safety and Health began <br />> studying that question after the World Health Organization in <br />> 2011 categorized RF <br />> radiation as a possible carcinogen, based on research by over 30 <br />> scientists, said <br />> Gregory Lotz, <br />> the top RF expert for <br />> NIOSH. And the National Toxicology Program at the National <br />> Institutes of Health is exploring lower-level RF exposure. An FCC <br />> guideline written after <br />> the rules were adopted notes studies showing "relatively low <br />> levels" of <br />> RF radiation can cause "certain changes in the immune system, <br />> neurological effects, behavioral effects," and other health <br />> issues, including cancer. "Results to date have been <br />> inconclusive," however, the <br />> agency said in a guide to radio-frequency radiation, and need to <br />> be studied further. Among those concerned is <br />4 <br />