One recommended tactic to prevent soot contamination is to employ mesh screening around building vents in eaves, siding, dryers and roofs. However, the National Fire Protection Association reported on a study by the Insurance Institute for Business and Home Safety that found that even with the recommended eighth-inch mesh screening, embers were still able to penetrate a building’s HVAC system. Filters are also not fail-safe.
“If there’s a lot of ash, the filters can load up and pass the debris through,” said Dan Stradford, a National Air Duct Cleaners Association board member and owner of Action Duct Cleaning in Altadena, California.