This article is a commentary on the following study: Mott JA, Wolfe MI, Alverson CJ, Macdonald SC, Bailey CR, Ball LB, Moorman JE, Somers JH, Mannino DM, Redd SC. National vehicle emissions policies and practices and declining US carbon monoxide-related mortality. JAMA 2002 Aug 28;288(8):988-95. This study provides an interesting description of CO-related mortality in the United States over a period of more than 30 years. It analyzes the role played by CO emissions regulations—and, in particular, by the introduction of catalytic converters after 1975—in the observed decline in motor vehicle-related deaths. Despite this decline, CO poisoning remains a major cause of death by poisoning in the United States, with more than 1,700 suicides and 500 accidental deaths each year. Progress in vehicle emissions regulations has prevented many deaths, but it must not be overlooked that deaths from carbon monoxide poisoning continue to occur, even with newer vehicles. These deaths result either from specific conditions of use in inadequately ventilated spaces, leading to oxygen depletion when the vehicle is in use, or from a gradual loss of efficiency in the catalytic converter. It would also be highly beneficial to conduct such a systematic study on deaths in France. (Conclusion)