Carbon monoxide in United States Homes: Installation quality, the inspection gap, and why alarms are not a cure

Carbon monoxide (CO) remains a leading cause of unintentional non-fire poisoning death in the United States, killing several hundred people and generating tens of thousands of emergency department visits each year despite decades of awareness campaigns and the near-universal spread of CO alarm laws. This review re-centres the problem on the US domestic context and argues that the great majority of these exposures originate from ordinary fuel-burning appliances—furnaces, gas water heaters, ranges, and, during power outages, portable generators—whose safety is determined by the quality of their installation, servicing, and inspection. Drawing on peer-reviewed literature published from 2020 onwards, supplemented by official US data where necessary, it develops four linked arguments. First, the installation and maintenance defects that generate CO—incomplete combustion, cracked or fouled heat exchangers, blocked or disconnected flues, and inadequate ventilation—are identifiable by established engineering tests and are therefore rectifiable. Second, the United States has a structural inspection gap, because periodic safety inspection and servicing of fuel-burning appliances are not mandatory in owner-occupied homes, in contrast to the annual landlord duty operating in the United Kingdom, so that latent defects accumulate undetected. Third, appliance safety decays over time without routine servicing, converting sound installations into hazards. Fourth, CO alarms, although valuable and required by law in most US states, are a reactive last line of defence: they warn only once CO is already present and can be defeated by expired sensors, dead or removed batteries, incorrect siting, or absence. The review concludes that reducing US CO deaths depends principally on a competent, well-trained installer workforce and on closing the inspection gap, with alarms retained as a secondary safeguard.