Prolonged or repeated exposure to benzene causes cancer. The City’s goal is to prevent community exposure to even brief periods of elevated benzene, also known as benzene events. The City defines a benzene event as an averaged ten-minute period with a reading of 3 ppb or higher. This is a more cautious approach compared to the State of Colorado which considers benzene a concern for long-term exposure to concentrations above 3 parts per billion (ppb).
In our first year of monitoring, 14 benzene events were recorded. The City established a target of zero benzene events per year. These events are most often due to oil and gas activity in the region.