Roofing Frequently Asked Questions

Reroofing of college buildings is a necessary part of building preservation. During such projects roof tar odors are generated. The following information addresses some of the common concerns associated with roofing projects, and some methods for reducing problems.


I smell roof tar odors. Does this mean I am being over exposed to a chemical?

No. The sulfur compounds in roofing tar have very low odor thresholds (in the parts per billion range). Smelling the odors does not indicate over exposure.


I smell roofing tar; my head aches; and I am feeling nauseated. Is this a short term problem or can it result in chronic health problems?

These can be short term or acute effects of exposure to roof tar odors. The symptoms should resolve within hours after exposure to the odor has stopped. Long term health consequences are not expected for the levels found inside buildings during roofing projects.


I am pregnant, will the roof tar odors affect my baby?

There is indirect evidence that exposure to roof tar chemicals may cause birth defects. Laboratory studies of roof tar extracts have shown DNA changes in human fetal cells exposed to asphalt fume extracts. This may be a concern for asphalt workers because of the higher exposure to fumes, but not for building occupants with a much lower exposure.


Can breathing roof tar vapors cause cancer? What about skin contact?

There is no direct evidence linking the inhalation of roof tar odors to the onset of any cancers. Some epidemiological studies of asphalt workers suggest that they may be at increased risk for skin, lung, stomach, and bladder cancer as well as leukemia. Other studies have been inconclusive. Skin contact with the roof tar has been shown to cause tumors in laboratory animals.


I have asthma, bronchitis, and other lung problems. Can inhalation of roof tar odors aggravate my condition?

Yes, the roof tar odors can irritate the respiratory tract and aggravate the condition of a person with asthma or other lung conditions. People with asthma should avoid breathing roof tar fumes.


Can hot roof tar produce hydrogen sulfide? Will it be at levels high enough to affect building occupants?

Yes, hydrogen sulfide can be produced from hot roof tar. The levels produced will not be high enough to affect building occupants. Only levels inside an enclosed asphalt kettle may be high enough to pose a serious health threat.

Methods to reduce odors during roofing projects


Building Occupants:

  • If your building has operable windows do not open them. Opened windows are the easiest and quickest way for odors to enter the building.
  • Schedule regular updates on the progress of the roofing project with members of the Facilities Department. Establish a contact person to disseminate project updates and forward building occupant concerns.
  • Promptly report roof leaks during construction to the Facilities Department.

Facilities Department:

  • Occasionally the ventilation system will need to be shut off during the project. It should be restarted during the evening when the roofing project has stopped for the day.
  • Communication between the roofers, a building representative, the project manager, and the building occupants needs to be clear.
  • Placement of the asphalt kettle is important. Every effort should be made to place it as far away as possible from the building’s air intake. Vehicle exhaust should also be considered as inappropriate vehicle placement could enable exhaust to enter the building.
  • Prior to construction consider other types of non-tar based roof construction.
  • In areas where it is difficult to keep roof tar odors out of the building consider doing the roofing work off hours in the evening or on the weekends. The air intakes will be closed during the roofing and opened 2 hours prior to occupancy to clear the odors out of the building.
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