Your Car Produces Carbon Monoxide. It Has No Detector. NHTSA Has Known Since 1993.

On July 15, a grandmother and four children under five sat in a car with a flat tire in Toledo, Ohio. Engine running. They needed the air conditioning. Within hours, Candace McAllister, 36, and four kids named Liberty, Storm, Legacy, and Stone were dead. When investigators put a CO meter inside the vehicle, the reading was five times the lethal limit.^[1]

Carbon monoxide killed them. Odorless, colorless, tasteless. It makes your head hurt, then makes you sleepy, then kills you while you think you're napping. We put CO detectors in furnace rooms, in hallways, in basements, in hotel rooms. We put them everywhere combustion happens except inside the combustion machine itself. Roughly 1,500 Americans die from vehicle-related CO poisoning every year. About 500 of those are accidental, per CDC data stretching back to the late 1970s, and 57% of all unintentional CO deaths involve motor vehicle exhaust. Of those, 83% happen in stationary vehicles.^[2][3] Parked. Idling. Waiting for a tow truck, or warming up in winter, or keeping the AC on for kids in the back seat.

In the early 1990s, NHTSA contracted the Carnegie Mellon Research Institute to evaluate whether a metal oxide semiconductor gas sensor could work as a low-cost CO monitor in vehicle cabins. Carnegie Mellon concluded that the technology was "at the point where a stable selective CO monitor is within reach" and recommended NHTSA pursue further research.^[4] That was 1993. NHTSA pursued nothing.

In March 2016, Public Employees for Environmental Responsibility filed a formal rulemaking petition asking NHTSA to require CO detectors and engine cut-off devices in all new gas-powered vehicles. PEER called it "the most cost-effective auto safety measure since seat belts." On January 28, 2018, NHTSA denied the petition. No explanation was offered. PEER sued under FOIA. NHTSA still hasn't said why.^[5]

Your house almost certainly has a CO detector. Thirty-nine states plus D.C. mandate them in residences. A combo smoke-CO alarm runs $30 at Home Depot. Residential CO detectors have saved thousands of lives since becoming standard in the 2000s, according to the Consumer Product Safety Commission. But the machine that actually produces the carbon monoxide? Where you sit for hours, windows sealed, recirculating cabin air through an HVAC system bolted to a combustion engine? No detector. No mandate. No explanation from the agency that studied the fix three decades ago and decided to do nothing. Twice.

Between 2013 and 2015, NHTSA issued CO-related recalls for nearly 100,000 passenger vehicles. Class-action litigation alleged that as many as 750,000 Ford Explorer SUVs were funneling exhaust fumes directly into the cabin, with rear-seat passengers absorbing the highest concentrations.^[6] More than half of the 17 million new vehicles sold in the U.S. each year now use keyless ignition, a system that lets your engine run indefinitely after you walk away with the fob. Safety Research & Strategies has tracked at least 37 CO deaths linked to keyless ignition since 2006.^[7] Senator Tina Smith wrote to NHTSA calling keyless ignition CO a "clear safety problem."^[8] NHTSA agreed it was a problem. Still no rule.

Counterargument, since someone will make it: electric vehicles don't produce CO, and the fleet is electrifying. Problem solves itself, right? EVs are 9% of new vehicle sales. Average vehicle age in America is 12.6 years. Most of the 290 million registered vehicles on U.S. roads still burn gasoline. Even under optimistic EV adoption curves, the internal-combustion fleet won't meaningfully shrink for another 15 to 20 years. Five people died in Toledo last Tuesday. Not in 2040.

A new car in America averages over $48,000. Adding a CO detector costs roughly $5. Thirty-three years of knowing. At even 200 preventable deaths per year, that's somewhere in the vicinity of 6,600 people since Carnegie Mellon told NHTSA the sensor worked. Five of them were in Toledo last week. Four hadn't started kindergarten.

What you can do right now: Buy a battery-powered portable CO detector for your vehicle ($30–$40). If you have a keyless ignition, check whether your car has automatic engine shutoff after extended idling. If your car has a flat or breaks down, turn the engine off and get out if it's safe to do so. Check whether your vehicle model has had CO-related recalls at nhtsa.gov/recalls.