The CPSC and the ODS
The CPSC first got involved with space heaters in 1974 when it received a petition from the Missouri Public Interest Research Group to ban all "space heaters." The request was apparently prompted by a tragic fire, ignited by an electric space heater, that claimed the lives of several children in Missouri. At the time, the commission did not understand the differences between the various types of space heaters (that is, electric, gas-fired, kerosene, and wood-fueled), let alone differences in styles and models. Choosing not to read the petition narrowly, and with a predisposition to grant it, the commission approved the petition "in substance" and directed the staff to figure out which space heaters should be banned.
It took the CPSC several years to become familiar with the world of heating appliances. The education process was terribly frustrating for AGA Labs and GAMA. "They just didn't understand the equipment," complains a GAMA staff member who tried, with mixed success, to point out the difference between vented and unvented gas space heaters. The agency's uncertainty stemmed largely from ignorance, but it was also indicative of a larger problem. Gas appliances, like most consumer products, are diverse and difficult to analyze with specificity. The CPSC's injury surveillance reporting system did not have a product code for unvented gas space heaters. Few of the newspaper reports collected through the Injury Surveillance Desk specified whether or not the appliance was vented. Even the CPSC's own "in-depth investigations," intended to compensate for data problems elsewhere, were sketchy and sometimes of questionable accuracy. Thus, even when they tried to find out specifically about unvented heaters, the staff had trouble obtaining helpful information.
Eventually the CPSC singled out the unvented gas space heater, deciding that it should be banned and that vented gas heaters and other types of space heaters need not be regulated at all. The overriding concern about the unvented gas space heater was carbon monoxide poisoning. "The thing that motivated the commission most over the years," according to a former commissioner, "was the actual experience of consumers as manifest by death and injury statistics." In this case, people were dying in their sleep—as many as seventy a year, according to the widely cited CPSC estimate. Industry representatives took issue with the figure. In addition to echoing familiar criticisms of the CPSC's information system, they argued that changes in the product had rendered it much safer in recent years. A representative of the Gas Appliance Manufacturers Association boldly claimed that there had been no carbon monoxide deaths involving heaters built after 1978. There is no way to prove or disprove this allegation with existing data.
Criticisms of the government's injury estimates masked a larger complaint about its motives. The unvented heater was a "politically targeted product," charged one industry representative. "It isn't nearly as bad as the kerosene heater," charged another, who manufactures only gas equipment. In fact, political forces favoring regulation of the gas space heater were in motion long before the commission received the petition from Missouri. The unvented gas space heater was investigated by the FDA in the early 1970s, and by the Public Health Service before that. It was also mentioned by the Presidential Commission on Product Safety, precursor to the CPSC.
If the unvented heater was politically targeted, the CPSC missed the mark—sort of. The agency was set to ban the product when word arrived of a technological answer to carbon monoxide poisoning. The ideal solution, a carbon monoxide sensor, had always been considered far too expensive to be practical, but a second-best solution—an oxygen depletion sensor (ODS)—was touted by a European manufacturer, Sourdillion, at the CPSC hearings in 1978. Similar to a pilot flame, the ODS consists of a Bunsen burner that utilizes a synthetic ruby orifice and other precision parts to achieve uniform control of aeration and flame characteristics (see figure 3). The ODS is a delicate device; it relies on an unstable flame, also known as a metastable flame. It is stable with normal levels of oxygen but less stable as oxygen levels decrease, to a point where the flame literally lifts off and shuts down the heater.
Since the CPSC was prohibited by statute from banning products for which there was a viable private standard, Sourdillion's presence at the
hearings demanded attention. Even those commissioners who personally favored a ban felt obligated to examine the ODS option. The CPSC's in-house engineers examined the device, and the agency contracted with NBS for additional research.
The most startling thing about the CPSC's analysis of the ODS is how late it occurred in the discussion of unvented heater safety. The device was introduced in 1961 in Europe. In 1972 the Z21 committee appointed a subcommittee to "follow the development of such devices and, if warranted, to develop revisions" for existing standards. (They had not yet done so when the CPSC first got involved in the issue.) Remarkably, it was not until 1978, four years after receiving the petition to ban space heaters, that the CPSC acknowledged the existence of these devices. Even then, in a January 1978 briefing package, the staff informed the commission that although the device "might be technically feasible [it is] economically impractical."
The European manufacturer, which boasted worldwide sales of thirty million units since 1961, begged to differ. But the success of the ODS in Europe must be put in context. European fuel gases differ from those widely available in this country, so technology that works in Europe will not necessarily work in the United States. To Sourdillion, however, adapting the ODS to this country did not pose anything more than a good engineering challenge. Still, there were two important respects in which the reliability of the ODS was called into question. First, the device does not measure carbon monoxide; it measures oxygen. Whether the relationship between oxygen and carbon monoxide was sufficiently predictable for the ODS to provide reliable protection against specified levels of carbon monoxide was a legitimate concern. Second, the metastable flame can be inhibited by dirt and lint. The dirtier the pilot, the more stable the flame and the less reliable the shutoff. How reliably the shutoff device would work in the field was a serious concern. (It was not an equivalent concern with European equipment, which requires the pilot light to be lit with each use, minimizing the amount of dirt and lint.)