Valley Fever is caused by Coccidioides immitis, a microscopic fungus that lives in the top 2 to 12 inches of soil across large portions of the western United States. When the soil is disturbed, spores may become airborne and inhaled, which can lead to serious health issues. Assembly Bill No. 203 (AB 203) requires employers in counties where Valley Fever is highly endemic to provide effective awareness training annually and before employees begin work that can be reasonably anticipated to result in exposure to substantial airborne dust.

AB 203 applies when:

  1. Employees are working at worksites in Counties where Valley Fever is highly endemic, including Fresno, Kern, Kings, Madera, Merced, Monterey, San Joaquin, San Luis Obispo, Santa Barbara, Tulare, and Ventura. (Highly endemic means that the annual incidence rate of Valley Fever is greater than 20 cases per 100,000 persons per year.), and;
  2. Employees are performing activities that can reasonably be anticipated to cause exposure to substantial dust disturbance. Substantial dust disturbance means visible airborne dust for a total duration of one hour or more on any day and includes, but is not limited to, digging, grading, or other earthmoving operations, vehicle operation on dirt roads, or dust disturbance due to high winds.

Supervisor & Departmental Responsibilities

Departments and their supervisors have the primary responsibility of ensuring the health and safety of their employees. Supervisors who have employees that work in areas endemic to Valley Fever must implement certain control measures to protect employees. Assembly Bill No. 203 (AB 203) specifically requires that employees be provided effective awareness training annually and before an employee begins work that is reasonably anticipated to cause a substantial dust disturbance. Training for employees must be documented and include the following topics (training resources available below):

  1. What Valley Fever is and how it is contracted.
  2. High-risk areas and types of work and environmental conditions during which the risk of contracting Valley Fever is highest.
  3. Personal risk factors that may create a higher risk for some individuals.
  4. Exposure prevention methods.
  5. The importance of early detection, diagnosis, and treatment to help prevent the disease from progressing.
  6. How to recognize common signs and symptoms of Valley Fever.
  7. The importance of reporting symptoms, seeking medical attention, and proper diagnosis.
  8. Common treatment and prognosis for Valley Fever.

Additionally, Cal/OSHA provides the following recommendations for preventing Valley Fever:

  • Determine if a worksite is in an area where fungal spores likely are to be present.
  • Train supervisors and workers in how to recognize symptoms of Valley Fever and minimize exposure.
  • Develop a site plan and work practices that minimize the disturbance of soil and maximize ground cover
  • Limit workers’ exposure to outdoor dust in disease-endemic areas by providing (1) air-conditioned cabs for vehicles that generate dust and making sure workers keep windows and vents closed, and (2) providing sleeping quarters, if applicable, away from sources of dust.
  • Use water, appropriate soil stabilizers and/or re-vegetation to reduce airborne dust.
  • Work upwind from dusty areas when feasible
  • Suspend work during heavy winds
  • Limit dust contamination of food, drinks, clothes, etc.
  • Perform wet cleaning of dusty equipment when feasible
  • Practice good hygiene when skin and clothing is soiled by dust
  • Wear a respirator (N95 or more protective) when exposure to dust cannot be avoided (requires EH&S approval)

Training Resources

To assist departments and supervisors in meeting their responsibilities, Environmental Health & Safety (EH&S) has provided the resources below. EH&S can also assist departments with additional questions or concerns upon request.

Training Videos

Additional Training, PowerPoints, and Training Guides

Posters, Handouts, and Fact Sheets

Additional Resources

For questions regarding Valley Fever, please contact the Industrial Hygiene Program at