Impact of mandatory carbon monoxide alarms: An investigation of the effects on detection and poisoning rates in New York City

Objectives. We sought to evaluate the impact of New York City's (NYC's) 2004 carbon monoxide (CO) alarm legislation on CO incident detection and poisoning rates. Methods. We compared CO poisoning deaths, hospitalizations, exposures reported to Poison Control, and fire department investigations, before and after the law for 2000 to 2010. Use of CO alarms was assessed in the 2009 NYC Community Health Survey. Results. Investigations that found indoor CO levels greater than 9 parts per million increased nearly 7-fold after the law (P < .001). There were nonsignificant decreases in unintentional, nonfire-related CO poisoning hospitalization rates (P = .114) and death rates (P = .216). After we controlled for ambient temperature, the law's effect on hospitalizations remained nonsignificantly protective (incidence rate ratio = 0.747; 95% confidence interval = 0.520, 1.074). By 2009, 83% of NYC residents reported having CO alarms; only 54% also recently tested or replaced their batteries. Conclusions. Mandating CO alarms significantly increased the detection of potentially hazardous CO levels in NYC homes. Small numbers and detection bias might have limited the discovery of significant decreases in poisoning outcomes. Investigation of individual poisoning circumstances since the law might elucidate remaining gaps in awareness and proper use of CO alarms.