By Pam Susi
Roofing is the fundamental barrier between a school’s indoor environment and the natural elements. Exposure to sun, rain, wind and ice cause wear and tear on roofs that may result in cracks, leaks and more serious damage. Roof repairs are vital to prevent water from entering school buildings and causing mold growth and, if severe, structural damage.
Without maintenance, repair, and eventually, replacement, health and safety problems can result—the most common being indoor air quality (IAQ) related. Since air intakes are often located at roof level, dust and vapors from roofing jobs may migrate into the school and result in exposure to staff and students.
A surprising number of chemical hazards are encountered in roofing, beginning with the “tear-off” of old roofing. Since asbestos was used in roofing felts into the early 1980s and built-up roofs (BURs) last several decades, asbestos fibers may be released during removal. Asbestos was also used in roofing cements and in some early single ply roofing systems.
The hazards encountered during roofing are dependent on the type of roof. Flat BURs were the longtime norm for schools. These roofs are constructed with alternating layers of felt paper and either coal tar pitch (CTP) or asphalt heated in kettles and mopped onto the roofing deck. Now a wide variety of roofing products are available on the market. Single ply and synthetic rubber roofing systems have become increasingly common
The products used for “hot” work—CTP and asphalt—generate polynuclear aromatic hydrocarbons (PNAs) and cause irritant effects, particularly on skin and mucous membranes. PNAs found in petroleum asphalt and CTP have also been shown to cause cancer after long-term exposure, with CTP being the more potent carcinogen of the two.
While installation of new roofs using CTP may be less common, these roofs perform well and may last 50 years if well maintained. New Jersey specifications instruct school contractors to “match the existing system and follow… recommended practices wherever possible.” Restoration of existing BURs can be accomplished “hot”—using the process previously described—or “cold,” with solvent based restorants. The odors from these processes, poorly controlled jobs, and existing ventilation deficiencies can conspire to wreak havoc within occupied schools.
According to a report from the National Institute for Occupational Safety and Health (NIOSH), at one Pennsylvania school where roofing repairs were underway involving use of CTP restorants, numerous children went home with complaints of headaches, burning eyes, and respiratory and other symptoms. Over the course of the school year there were repeated episodes of illnesses resulting in several days of unscheduled school closures. Two students and one teacher suffered with asthma symptoms.
Six months after work was completed and temperatures had warmed up, volatile organic compounds (VOCs) from the roof’s surface vaporized and traveled into the building. Absent sufficient fresh make-up air and adequate air circulation to dilute the VOCs once in the building, the problem persisted long after the roofing job had ended.
Chemical compounds known as isocyanates are in adhesives and foam insulation material used with newer single ply roofing systems. Exposure to isocyanates is irritating to the eyes, mucous membranes and respiratory tract. The most common serious health effect associated with isocyanates is asthma resulting from sensitization. This usually occurs after repeated exposure over months or years but can occur after a single exposure. Once sensitized, even exposure to nondetectable levels can cause asthmatic reactions.
At one Texas school, NIOSH found asthma occurring in school workers at least three times as often as seen in the general population. It concluded that isocyanates from a roofing project had likely entered through air intakes, windows or other building openings. IAQ problems already existed, but after roofing foams, coatings and sealing compounds containing isocyanates were used while the school was in session, the problem grew much worse.
Local associations and their health and safety committees should work with their UniServ field representatives to insist on greater transparency, better communication and more involvement in the construction planning process. Locals should act quickly upon notification of upcoming roofing work to insist that districts:
• Schedule work when school is not in session.
• Close windows, air intakes and other building openings to prevent entry of fumes and vapor.
• Flush out contaminants with fresh air before re-occupying.
• Obtain copies of Safety Data Sheets for products used and retain them for future reference.
The local association should insist on a pre-roofing meeting with the district and contractor and ensure the contractor will:
• Wet asbestos before removal.
• Use less hazardous methods and materials such as mechanical fasteners rather than adhesives containing isocyanates, low-fume asphalts, and application methods that don’t require spraying adhesive and foam, including hand-held extrusion pumps.
• Use roofing kettles equipped with after burners and safety loaders that allow for keeping the kettle lid closed, reducing emission of fumes.
• Keep kettle temperatures as low as possible; the temperature used for asphalt varies depending on the type; contractors should not exceed the equiviscous temperature (EVT), which is the optimum application temperature for wetting and adhesive properties.
• Place kettles, pumps and equipment used to channel asphalt to the roof away from windows, doors and air intakes.
Low bid requirements for state contractors may result in nonunion contractors with poorly trained workers getting the work. Urge districts to make sure that contractors are trained and qualified by writing into job specifications that contractors must be participants in joint labor/management apprenticeship programs registered with the U.S. Department of Labor.
Pam Susi holds a Master of Science in Public Health from the University of North Carolina at Chapel Hill in and is a certified industrial hygienist. She is a consultant with the New Jersey Work Environment Council, which is a frequent partner with NJEA on school health and safety concerns.