There are a couple of potential common causes for a rotten egg odor. These include a natural gas leak or the presence of "sewer gas" in the vicinity.
Information about natural gas leaks – from the National Institute of Health
The following Web sites provide information on sewer gas:
- Agency for Toxic Substances and Disease Registry: ToxFAQs for Hydrogen Sulfide
- Wisconsin Department of Health & Family Services: Sewer Gas
- Illinois Department of Public Health: Environmental Health Fact Sheet: Hydrogen Sulfide Gas
- Find Regional and State Indoor Air Quality Contact Information
- Find answers to frequent questions or submit your question about indoor air quality
If the smell is coming from outdoors, you may want to contact your public works department to inquire about a possible sewer main break.
If this is a workplace issue, you may also want to contact the U.S. Occupational Safety and Health Administration (OSHA).