The "landmark" regulation comes almost five years after a chemical release and fire at US oil giant Chevron's refinery in the Californian city of Richmond, which reportedly caused 15,000 people to seek medical attention.
The new regulation provides a framework to help the state's refinery workers "anticipate, prevent and respond to hazards".
It requires employers to:
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Carry out damage mechanism reviews for processes that can cause equipment and materials to degrade, including corrosion and mechanical wear, which are common technical causes of serious process failures.
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Conduct a hierarchy of hazard controls analysis
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Use root cause analysis when investigating any incident that results in, or could have resulted in, a major incident.
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Perform and document a process hazard analysis of the effectiveness of safeguards that apply to particular processes and identify, evaluate and control hazards associated with each process.
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Implement human factors programmes and examine issues such as staffing levels, training and competency, fatigue and other effects of shift work, and the human-machine interface.
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Develop, implement and maintain written procedures that will ensure plant safety remains consistent during personnel changes.
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Understand employees' safety attitudes, beliefs, perceptions and values and evaluate responses to hazard reports via process safety culture assessment programmes.
Several Californian refineries have already adopted some of the practices outlined in the new regulation and safety performance has improved at those refineries, the DIR said. However, major incidents still occur in the refining industry, it noted.
DIR director Christine Baker described the regulation as "the most protective legislation in the nation for the safety and health of refinery workers and surrounding communities".
The California Office of Administrative Law now has 30 working days to review and approve the regulation.