Nine air samples by residents near natural gas drilling in Colorado and New Mexico found four carcinogens and 18 other toxic chemicals, a new report says.

The nonprofit group Global Community Monitor says that in some cases chemicals were found at levels from three to 3,000 times levels deemed safe by state and federal agencies for long-term exposure. Although the samples are one-time measures, the group says it believes they are indicative of long-term exposures.

The monitoring found numerous instances of high levels of the carcinogen benzene and other toxins in the Durango area. One Garfield County site, on Silt Mesa, was included in the study report. There, a sample taken Jan. 15 found hydrogen sulfide at a level more than 185 times above the long-term amount the Environmental Protection Agency believes creates an increased risk of serious health impacts, the report says.

The family involved in that case, the Strudleys, reported a rotten-egg smell and said they suffered from headaches, nosebleeds and rashes. They since have moved from their home and sued Antero Resources, which has drilled exploratory wells on Silt Mesa, including one about a half-mile from their home.

Most other toxins tested for in the air sampled at the Strudleys’  were not detected, although toluene, hexane and heptane were found at levels not considered dangerous.

Global Community Monitor trains people serving in so-called “Bucket Brigades” to do air sampling using collection equipment contained in buckets. The samples are analyzed by certified labs.