ANSI Z590.3 explained: 4 design decisions

F7 glossary for EHS managers, engineers, supervisors, and safety students

ANSI/ASSP Z590.3 is the US consensus standard for Prevention through Design, and it matters whenever a hazard can be reduced before workers inherit it as a field control problem. This explainer maps the standard to four decisions that move risk upstream.

ANSI/ASSP Z590.3-2021 is a structured approach for identifying and reducing occupational hazards during the design of facilities, equipment, processes, and work methods. It asks designers, owners, engineers, and users to consider worker exposure before construction, purchase, commissioning, or operation makes the risk expensive to change.

Definition

ANSI/ASSP Z590.3-2021 does not replace OSHA rules, an ISO 45001 management system, or a task-level risk assessment. It gives those systems an earlier decision point. Instead of waiting for a supervisor to compensate for an awkward layout, an unguarded access point, or a maintenance task that requires line-of-fire exposure, the design team examines whether the exposure can be removed or reduced at its source.

The distinction is important because a later control often depends on memory, inspection, or perfect execution. A design decision can change the physical relationship between the worker and the hazard, which makes the safer method less dependent on individual vigilance. In Safety Culture: From Theory to Practice, Andreza Araujo connects credible safety culture with the choices that make safe work practical, not merely with messages about care.

4 design decisions in ANSI Z590.3

1. Remove the exposure before adding instructions

The first decision is whether the hazard needs to reach the worker at all. A designer might relocate a chemical connection outside a routine access zone, replace manual handling with mechanical movement, or change a maintenance point so isolation can be verified from a safe position. The question is not whether a procedure can manage the exposure. It is whether the exposure, which the project can often remove before commissioning, needs to be designed into the work.

2. Reduce the energy that remains

When removal is not feasible, the next decision concerns energy, access, and consequence. Lowering stored pressure, reducing machine speed during setup, limiting reach distance, or separating people from vehicle paths can reduce the severity of a foreseeable error. The design review should record the hazard, the affected worker, the energy source, and the reason a lower-energy option was accepted or rejected.

3. Make the safe method the easy method

A control that requires 6 separate actions before every intervention is vulnerable when production pressure rises. The preferred design makes the correct sequence visible and physically compatible with the work. Examples include captive fasteners, keyed connections, fixed access platforms, and sampling points that do not require a worker to lean across an opening. Andreza Araujo’s leadership work emphasizes that supervisors cannot coach their way out of a design that repeatedly creates the same bad choice.

4. Preserve evidence for the next decision

Prevention through Design is not complete when a drawing is approved. The team needs evidence that the selected control survived procurement, installation, commissioning, and use. A useful record identifies the design owner, the remaining exposure, the verification date, and the trigger for review after a modification or incident. The 4 stages are different from a generic checklist because each one assigns a decision before work becomes routine.

How to differentiate it in practice

Use the table below when a project team says that an existing procedure already controls the hazard. A procedure may still be necessary, although the design review asks whether the procedure is carrying a burden that belongs in the equipment, layout, or process.

For a broader introduction, read the Prevention Through Design overview. For a control-focused comparison, see collective protective measures before PPE. These two articles complement the standard-specific lens used here.

When to use ANSI/ASSP Z590.3 versus a task review

Use ANSI/ASSP Z590.3 when a facility, machine, process, or work method is being created or changed, because that is when the organization can still alter the source of exposure. Use a JSA or JHA when the work already exists and the team needs to understand task steps, conditions, and controls. The strongest system connects both reviews rather than asking a task analysis to repair a design that was never challenged.

Andreza Araujo’s experience across 25+ years of multinational EHS leadership, 250+ companies, and 30+ countries supports a practical conclusion. Prevention through Design is not an engineering-only exercise. It is a leadership test of whether the organization is willing to spend decision time before workers spend exposure time. During her PepsiCo South America tenure, a 180-day plan contributed to a 50% reduction in accident ratio in 6 months, a reminder that prevention improves when choices are translated into operating routines.

Make the next design review more useful. Explore Andreza Araujo’s safety culture and leadership resources for methods that connect engineering, creativity, and care.