Air Quality - Part I

We asked Dr. Damian to review the DEIR as it relates to air quality. Here are a few of his and our observations contained in our April 14, 2008 submission:

  1. C-Silica Chronic REL and DPM Not Stated. The chronic reference exposure level established by the California Office of Environmental Health Hazard Assessment for c-silica (3 µg/m³) and diesel particulate matter (DPM) (5 µg/m³) is not stated anywhere in the DEIR. This prevents readers from drawing their own conclusions about the critical health risk benchmarks for air contaminants. (A chronic reference exposure level or REL is an airborne level of a chemical at or below which no adverse health effects are anticipated in individuals indefinitely exposed to that level.)
  2. Carcinogenicity of C-Silica Not in Dispute. The DEIR implies that the carcinogenicity of c-silica is indeterminate or in dispute. This question has been settled by the leading international agency for classifying the carcinogenicity of compounds. The EIR should plainly state the International Agency for Research on Cancer (IARC) conclusions with respect to the carcinogenicity of C-silicaIn 1997, the International Agency for Research on Cancer (IARC). [NOTE: In 1997, the IARC changed the classification of crystalline silica from 2A (probable human carcinogen) to 1 (known human carcinogen). The change to IARC Type 1 means that occupational silica dust exposure is considered like other known human carcinogens such as asbestos, vinyl chloride, radon daughters, smoking, and DES. Other health risks of crystalline silica also exist, such as silicosis.]
  3. Community Has Very High Exposure to C-Silica. Dr. Damian states that many nearby residents of the Quarry are effectively experiencing occupational exposure to C-silica at an exposure level of 196 µg/m³ (versus the ambient benchmark of 3 µg/m³ and the occupational benchmark of 25 µg/m³) for periods longer than 30 days. The DEIR should state clearly the health risks posed by exposure at these levels.
  4. Crystalline vs. Amorphous Silica. The DEIR recognizes the toxicity of silica in its crystalline form, but equates the two crystalline and amorphous forms. Independent testing confirms that the area surrounding the Quarry is blanketed in dust that is comprised of over 25% crystalline silica, which is the dangerous type. The DEIR should make this point clearly.
  5. Improper Averaging of Annual Emission Rates. The DEIR’s Health Risk Assessment (HRA) improperly averages annual exposure to toxic air contaminants. Although the calculations were not provided in the DEIR’s appendix, Dr. Damian requested and received the backup data for the exposure calculations. He discovered, to his surprise, that annual average exposure levels over an individual’s presumed 70-year life assumed that the Quarry would shut down after 17 years and emit zero toxic air contaminants upon shutdown. In other words, the HRA averaged 17 years of substantial exposure to toxic air contaminants with 53 years of zero exposure. This is improper, and understates an individual’s exposure by more than 4-fold.