46 Process Safety and Mechanical Availability Process Safety Keeping employees and communities safe is a top priority. Our process safety and reliability programs provide safeguards for ensuring our equipment is correctly designed, regularly maintained and safely operated. In addition to capital investments in reliability, our industry-leading technical assessments are core to our commitment to excellence. These comprehensive programs, developed more than 10 years ago, promote consistent and best-in-class process safety and reliability expectations across our refining operations. From 2008 to 2018, Valero’s mechanical availability has improved from third quartile to industry-leading first quartile, and we continue to focus on maintaining our processing units as highly reliable. Our Tier 1 and Tier 2 Process Safety Event (PSE) three-year average rates have also set new records each year, as we continually focus on reducing process safety incident severity and frequency. 2021 set new records for safety performance. 2021 Process Safety Event (PSE) Rates Tier 2 2 0.05 Tier 1 1 0.08 0.15 0.18 Valero Industry 1 Tier 1 process safety event - Losses of primary containment of greatest consequence, causing harm to a member of the workforce, costly damage to equipment or exceeding defined quantities. 2 Tier 2 process safety event - Losses of primary containment of lesser consequence than Tier 1. Tier 1 PSE rate and Tier 2 PSE rate as defined by the API Recommended Practice 754.