In 1999, the federal government announced that oil companies will need to reduce the sulfur content of gasoline from 360 parts per million (ppm) to 30 ppm by January 2005. As a result, refineries across the country will be required to remove more sulfur from the crude oil they process, possibly resulting in higher concentrations of sulfur in their stack emissions. While this regulation is intended to protect Canadians from harmful compounds in tailpipe exhaust, communities close to oil refineries may be exposed to higher concentrations of those same compounds. Using air pollution and population data from five major Canadian refinery communities, Sarah Henderson is assessing the potential for sulfuric emissions from refineries to affect public health, and is determining how federal gas regulations could increase that potential. She hopes the research will lead to a model that policy makers can use to quantify how sources of air pollution can affect the health of surrounding communities.