TIJUANA RIVER VALLEY CHEMICAL POLLUTION IMPACT INVESTIGATION : EXPOSURE CHARACTERIZATION STUDY

2026-11-03

The primary goals of the Exposure Characterization Study are to identify and quantify the specific chemical exposures linked to the Tijuana River pollution . This includes : 3 . 1 . 1 . Contractor shall identify the airborne chemicals of most public health concern arising from the Tijuana River in South County , including Imperial Beach , Nestor , and San Ysidro . 3 . 1 . 2 . Contractor shall estimate levels of community exposure to the chemicals of most concern under varying meteorological conditions and at varying times of the day and develop a dispersion model . 3 . 1 . 3 . Contractor shall validate modeled results through ambient air sampling and chemical analysis across multiple sites . 3 . 2 . Outcome Objectives : Contractor shall achieve the following outcome objectives : 3 . 2 . 1 . Contractor shall assess emission levels and toxicological data for identified key chemical pollutants and compare modeled or measured concentrations to Reference Exposure Levels ( RELs ) promulgated by California Office of Environmental Health Hazard Assessment ( OEHHA ), or other relevant exposure recommendations . 3 . 2 . 2 . Contractor shall provide detailed information about how exposures vary across communities , including but not limited to diurnally and according to varying river flows and weather conditions , such as wind speed and direction , temperature , humidity , precipitation , mixing height , and other coastal or terrain - driven factors . 3 . 2 . 3 . Contractor shall define geographic exposure boundaries ( at least “ high ”, “ medium ” and “ low ”) for use in obtaining a selection of participants in the potential Panel Study that is balanced in terms of exposure levels and for defining community areas for comparison in the potential Retrospective Study . 3 . 2 . 4 . Contractor shall develop a web - based exposure software model that shall be made available for predicting pollutant concentrations at residential - level resolution , for community visualization of pollutant distributions , and generally to inform public health action . 3 . 2 . 5 . Contractor shall document all modeling assumptions , input parameters , data sources , and limitations to ensure transparency , reproducibility , and appropriate interpretation of exposure estimates .

California

2026-03-27