In the 1980s, the tobacco industry started a campaign to divert attention away from secondhand tobacco smoke (SHS) as a major source of indoor air pollution in workplaces by highlighting the roles of other indoor air pollutants. The industry, working through "third parties," highlighted endotoxins, naturally occurring substances that cause numerous inflammatory reactions in humans, as an alternative explanation to SHS as causing indoor air problems. In 1995, Hasday and colleagues were the first to present findings that cigarette smoke contains significant quantities of endotoxins. This discovery surprised tobacco industry scientists. The 1999 publication of the full Hasday et al. findings received only limited media attention but got the full attention of Philip Morris scientists concerned about a new public health issue and a new basis for regulation of workplace smoking by the U.S. Occupational Safety and Health Administration, which already regulated workplace endotoxin exposures from other sources. Philip Morris undertook an internal endotoxin research project to test the Hasday et al. findings and to determine if endotoxin-free cigarettes were possible. Although experiments were conducted to remove endotoxin from the tobacco, there is no evidence that they were successful. Following confirmation of SHS as an important source of endotoxins, the scientist promoting endotoxins as an important indoor air pollutant for the tobacco industry softened his position on the role of endotoxins as indoor pollutants. The presence of endotoxins in SHS provides an additional mechanism for the adverse effects of SHS that should be researched further, and the risk of exposure should be assessed.