Science / Medicine : Disfigurement in the Air

Two University of Delaware researchers have found that marble tombstones provide a unique record of air pollution that suggests the clean-up efforts of the last two decades appear to be working. By measuring the deterioration rates of about 2,000 tombstones in cemeteries from Newark to Norristown, Pa., geography professor Thomas C. Meierding and graduate student Johan Feddema have produced an outline of air pollution history in the Delaware Valley.

The study found extensive differences in pollution levels between areas and suggests that pollutants that have nearly dissolved some headstones likely have extensively damaged other structures.

Many tombstones in central Philadelphia -- the hardest-hit area in the study -- are so weakened from decades of sulfur dioxide deposits that they “flex under slight pressure,” Feddema said. In contrast, tombstones in Delaware cemeteries show less wear, and those in areas with excellent air quality, such as Hawaii and rural Nebraska, show almost no deterioration.