The CPSC Investigates the ODS
Sourdillion's presence at a Washington, D.C., hearing put tangible pressure on the CPSC. The firm apparently considered a mandatory standard the best way to create an American market for its product. The commission, committed to banning space heaters, was forced to reverse its position and examine the ODS (about which it knew practically nothing). The obvious technological question was whether the device would operate reliably under U.S. conditions. There were secondary technological questions as well. The cost of such technology was of prime concern to industry, but apparently less so to government.
To answer the basic technological question, the CPSC contracted with the National Bureau of Standards. Simple questions do not always elicit simple answers, however, particularly when a regulatory agency is asking and NBS is answering. In this instance, NBS gave a more complicated answer than the CPSC wanted. Yes, the ODS works, it concluded, but the shutoff level in the "optional AGA requirement"—an 18 percent oxygen level-might not be appropriate. A higher shutoff level, such as that used in the French standard, would be more protective, since the corresponding levels of carbon monoxide would be lower. The problem is that higher shutoff levels are also more likely to cause "nuisance shutoffs" (where the heater shuts off accidentally because the cutoff point is so close to normal levels of oxygen).
The origin of the 18 percent level remains something of a mystery. Minutes of the Z21 subcommittee meetings at which the ODS was first discussed do not reflect any discussion of the adequacy of the 18 percent level. An NBS engineer who analyzed these documents for the CPSC concluded that the figure most likely came from the American Conference of Government Industrial Hygienists, a nongovernment standards-writing organization (contrary to its name). Since the relevant health concern is carbon monoxide, however, and not oxygen, it would be strange indeed if the shutoff level for the ODS was selected without considering the estimated corresponding levels of carbon monoxide. More likely, members of the Z21 committee had a rough idea of the relationship between oxygen and carbon monoxide and made their decision without explicitly discussing the details. According to one frequent guest at the subcommittee meetings, "We knew what the curves would look like."
Whatever its origins, 18 percent appears to provide substantial margins of safety. The NBS tests revealed that ODS devices set for 18 percent
actually shut down at higher oxygen levels (18.2 to 20.4 percent). The corresponding carbon monoxide levels in those conditions ranged from 7 to 98 ppm, with a mean concentration of 37 ppm. A 1971 OSHA standard permits normal concentrations in the workplace of up to 50 ppm. At four times that level, the expected medical response, according to the CPSC's Directorate for Epidemiology, is a "possible mild frontal headache in two to three hours." Another twofold increase, and nausea is likely; twice again higher, unconsciousness.
The CPSC staff divided on the question of whether the shutoff level in the AGA standard was adequate. The Directorate for Engineering, sensitive to the "nuisance shutoff" problem concluded that 18 percent was "adequate" and that higher levels were probably "overly conservative." The Directorate for Epidemiology disagreed, urging reconsideration of the 18 percent level because it "appears to be based largely on technical feasibility rather than on possible health effects."
Whether the ODS device was commercially feasible was not a question that much interested the Program Management staff. A negative answer would have been humiliating. The proposed ban had already been tabled because of the ODS. Frustration grew as NBS engineers questioned the appropriateness of the 18 percent cutoff and industry raised the specter of nuisance shutoffs at higher levels. "We had to get a consistent story," explains one staff member. "First we said ban them, then we said no. We had to get our story straight." The story, then, was that the ODS was technically feasible and would work well with an 18 percent shutoff.
The issue never reached the commission. "Staff assured us that 18 percent was all right," recalls one commissioner. Actually, the staff was more pragmatic than it was satisfied. "Nineteen percent would have meant a five-year fight," recalls a staff member who favored the stricter level but was even more concerned about keeping things as simple and uncontroversial as possible. Eighteen percent had history on its side.