Protection from Valley Fever

Valley fever is an illness caused by a fungus found in the soil in many parts of California, especially the Central Valley and Central Coast. For some, it can be serious and even fatal. Workers who work outdoors are especially at risk if they dig or disturb soil, operate heavy machinery, or work in windy conditions without taking steps to prevent valley fever.

Health Care Providers

Information for Employers

  • Employers have a legal responsibility to immediately report to Cal/OSHA any serious injury or illness, or death (including any due to Valley Fever) of an employee occurring in a place of employment or in connection with any employment. Employers also have responsibilities to control workers' exposure to hazardous materials.
  • Applicable regulations with regard to Valley Fever protection and exposure can be found in the California Code of Regulations, Title 8, sections
  • Construction employers must train workers on Valley Fever prevention in counties where Valley Fever is highly endemic including but not limited to including, but not limited to, the Counties of Fresno, Kern, Kings, Madera, Merced, Monterey, San Joaquin, San Luis Obispo, Santa Barbara, Tulare, and Ventura. Other counties may be added to this list, depending on Valley Fever rates in future years.

What is Valley Fever?

Valley Fever is caused by a microscopic fungus known as Coccidioides immitis which lives in the top two to 12 inches of soil in many parts of the state. When soil is disturbed by activities such as digging, driving, or high winds, fungal spores can become airborne and potentially be inhaled by workers. Populations with more than 20 cases annually of Valley Fever per 100,000 people are considered highly endemic.

While the fungal spores are more likely to be present in the soils of the Central Valley, they may also be present in other areas of California. The map below shows the areas with the greatest incidence of reported human Valley Fever cases. Work-related cases of Valley Fever at solar installation plants in the Central Valley have drawn attention to the health risks faced by California workers whose jobs may expose them to fungal spores found in soil.

  • Fresno
  • Kern
  • Kings
  • Madera
  • Merced
  • San Luis Obispo
  • Tulare
California map that highlights of highly endemic counties: Fresno, Kern, Kings, Madera, Merced, San Luis obispo, Tulare with incidence rates of 75 to 304 cases per 100,000 people.
map source:  CDPH Valley Fever website portal

While there is no vaccine to prevent Valley Fever, the following steps are important to take in order to limit risk:

  • Determine if your worksite is in an endemic area.
  • For employers in the construction industry, follow the requirements to train workers in labor code section 6709.
  • Adopt site plans, controls, and work practices that reduce workers' exposure, which may include:
    • Minimize the area of soil disturbed.
    • Use water, appropriate soil stabilizers, and/or re-vegetation to reduce airborne dust.
    • Stabilize all spoils piles by tarping or other methods.
    • Provide enclosed air conditioned cabs for vehicles that generate dust and make sure workers keep windows and outside air vents closed.
    • Suspend work during heavy winds.
    • Keep workers upwind of digging and other dust-producing activities, such as grading, driving, dumping soil, drilling, or blasting.
    • Use vacuums equipped with HEPA filters, water, wet towels, or other wet methods to clean soiled equipment, tools, and surfaces. Do not use compressed air, dry sweeping, or other methods that create dust when cleaning.
    • Keep break areas, eating areas, and sleeping quarters, if provided, clean and protected from sources of dust.
  • When exposure to dust is unavoidable, provide NIOSH-approved respiratory protection with particulate filters rated as N95, N99, N100, P100, or HEPA. Employers must develop and implement a respiratory protection program in accordance with Cal/OSHA's Respiratory Protection standard (8 CCR 5144). Face coverings and masks do not protect against Valley Fever.
  • Take measures to reduce transporting spores offsite, such as:
    • Clean tools, equipment, and vehicles safely before transporting offsite.
    • At dusty worksites, provide coveralls and change rooms, and showers where possible. Ensure workers change into clean clothes and shoes before leaving the worksite.
  • Identify a health care provider for occupational injuries and illnesses who is knowledgeable about the diagnosis and treatment of Valley Fever
  • Train workers and supervisors about the risk of Valley Fever, the work activities that may increase the risk, and the measures used onsite to reduce exposure. Also train on how to recognize Valley Fever symptoms.
  • Encourage workers to report Valley Fever symptoms promptly to a supervisor. Not associating these symptoms with workplace exposures can lead to a delay in appropriate diagnosis and treatment.

When fungal spores are present, wind and any work activity that disturbs the soil, such as digging, grading or other earth moving operations, or vehicle operation on dirt roads, can cause the spores to become airborne, therefore increasing the risk of Valley Fever. All workers on sites where the fungus is present, and who are exposed to dusty conditions and wind-blown dusts are at increased risk of becoming infected.

  • Construction workers and other workers on construction sites, including road building and excavation crews
  • Archeologists
  • Geologists
  • Wildland firefighters
  • Military personnel
  • Workers in mining, quarrying, gas and oil extraction jobs
  • Agricultural workers *

* Cultivated, irrigated soil may be less likely to contain the fungus compared to undisturbed soils.

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February 2024