Thinking Outside
the Confined Space Box
Application of Prevention through Design Principles to Confined Spaces
The drawings above are from the San Francisco Public Utilities Commission’s Safe Design Guidelines. For more information, see the sidebar.
Fatalities in confined spaces remain a concern despite regulations and efforts to communicate with workers and employers about these hazards. In the United States, the Bureau of Labor Statistics (BLS) Census of Fatal Occupational Injuries indicates that an average of 92 confined space fatalities occurred each year from 1997 through 2011. In 2011 alone there were 7 fatalities in confined spaces in California, prompting the state to launch a confined space entry emphasis program the next year.
By definition, confined spaces are not designed for human occupancy. Yet it is often necessary to enter these spaces for maintenance, inspection, cleaning, or repair. With thoughtful planning, many of these confined spaces—and the need to enter them—could be eliminated entirely. If it isn’t possible to eliminate a confined space completely, good design can minimize the hazards within the spaces and allow for the safe, non-entry rescue of workers. These same design principles can often be applied to existing confined spaces where redesign can eliminate or minimize hazards. Still, up-front safe design is generally recognized to be more cost effective than a retrofit at preventing injuries and fatalities in confined spaces.
NIOSH has long recognized that one of the best ways to prevent and control occupational injuries and illnesses and fatalities is to minimize or eliminate hazards in the design phase. In 2007 the agency launched its Prevention through Design (PtD) initiative, which sits at the pinnacle of the hierarchy of controls. 
“PtD is the most effective means of preventing worker injury, illness, and death,” says NIOSH PtD Coordinator Jonathan A. Bach, PE, CSP, CIH. “The NIOSH PtD initiative ultimately seeks a culture change, where designing-out worker hazards at the planning stage becomes the expected norm. In boardrooms and design review rooms, we want to hear, ‘Why, of course we try to keep worker hazards out of our designs and plans.’”
PtD is facilitated when owners and operators responsible for confined space safety provide sufficient resources for safe design and assign safety professionals and engineers to collaborate during the early stages of a capital project. For a PtD process to function effectively, confined space owners and operators must understand the hierarchy of controls and recognize which confined space hazards and risks can be reduced through improved design or redesign.
Public support for legalizing marijuana has reached an all-time high in Gallup Polling with 58 percent of Americans supporting the movement. Last January, Fox News reported the stock price for a medical marijuana machine company increased 57 percent after Colorado legalized recreational use. The state reported over $5 million in taxed and regulated sales of marijuana during the first week of legalization and more than $200 million during the first four months. - Eric Nelson and Jeremy Slagley