The National Highway Traffic Safety Administration (NHTSA) has opened an investigation (called an engineering analysis) into consumer complaints of exhaust odors in the passenger compartment of Ford Motor Co.’s (NYSE: F) popular Explorer sport utility vehicle (SUV). The investigation was opened in late July and includes model years 2011 through 2017 vehicles. The agency also reported that the problem occurred in model year 2016 and 2017 Explorer Police Interceptor vehicles.

The NHTSA’s Office of Defects Investigation (ODI) identified three crashes and 41 injuries potentially linked to the exhaust odor issue. ODI has also identified 791 vehicle owner reports on the issue and 2,051 submitted to the manufacturer.

Owner complaints indicate that operating the vehicle with full throttle applications (e.g., climbing steep grades or merging onto freeway ramps) or using the air conditioning system in recirculation mode both contribute to exhaust gas being detected in the vehicle. The reported injuries range from unspecified to loss of consciousness, with the majority being nausea, headaches or dizziness – all of which can be symptomatic of carbon monoxide (CO) exposure according to the final ODI report.

In its initial report NHTSA noted:

To date, no substantive data or actual evidence (such as a carboxyhemoglobin measurement) has been obtained supporting a claim that any of the alleged injury or crash allegations were the result of carbon monoxide poisoning, the alleged hazard. ODI has obtained preliminary testing that suggests, however, that CO levels may be elevated in certain driving scenarios, although the significance and effect of those levels remains under evaluation as part of the EA.

We wrote about this issue this past Saturday and received an email that referred us to a web forum for Ford Explorer owners. One member of that forum, identified only as “Albert (CO toxicologist),” posted a list of steps to measure CO levels in both the vehicle and the vehicle’s occupants. Here are those recommendations:

If you can smell an exhaust odor, odorless CO is also present, but CO may be present even if you do not smell exhaust, or after the smell fades.
The only way to know the level of CO in a vehicle is with a professional CO detector that displays from 1ppm, and preferably one that records CO measurements automatically (called a data-logger) or at least one that records the peak CO level (which you can then recall by pressing a button). Any CO level above 0 in a vehicle is abnormal unless in heavy traffic or a tunnel, and healthy non-smokers absorb CO whenever the air has more than the 1-2ppm they normally exhale. If you can afford 2 detectors, I recommend putting one in the front seat and one in the rear, so you can determine from which end exhaust gases are entering (it could be either end or both).

Do not test vehicles with home CO alarms built to UL2034 or UL2075 standards.
These are worse than worthless for use in vehicles because they give a false sense of security. They do not display any CO levels below 30ppm in real time, nor do they give any CO warning below 70ppm, even though EPA average limit for public is just 9ppm. Worse still, these kind of alarms don’t provide any warning until CO has been continuously over 70ppm for 1 – 4 hours at the low end or over 400ppm for 4 -15 minutes at the high end. By the time they alarm, you have already been poisoned for anywhere from 4 minutes to 4 hours.

To get your Ford dealer to take you seriously, ask a passenger to use a smartphone to video the CO level your detector displays while you accelerate WOT [wide open throttle] over 45 mph with both the front and rear AC on high, all windows closed, and recirculate ON.
From my testing of 2015 and 2016 Explorers, this is consistently the worst case scenario and so the only condition you need to test. To quickly lower the CO level in the cabin after testing, leave the AC on and turn recirculate OFF (or open at least 2 windows). Since Ford dealers do not have CO detectors, I recommend you test your vehicle again after anyone attempts any repairs. As long as you can detect CO entering the cabin under these conditions, the vehicle is not safe to drive.

If you want to know how much CO you absorbed from your exposures while driving, you can use any professional CO detector to measure the level of CO in your tissues.
You just need to hold your breath for 35 seconds before exhaling into the detector. This method is faster, more accurate and less painful than measuring COHb in blood, which is most hospitals can’t even do in-house. If you do get your COHb tested, make sure they take both arterial and venous samples. Both are needed to determine if CO is being absorbed (a>v), excreted (v>a) or in equilibrium (a=v).

During CO exposure, you inhale more CO than you exhale, but afterwards, once back in fresh air, you exhale more than you inhale, until the level of CO in your blood and tissues tissues returns to healthy equilibrium. This can take days to years, depending on how much CO you absorbed, or until you are exposed to a higher level and start absorbing CO again. Symptoms like recurring headaches, chronic fatigue, brain fog, muscle pain and multi-sensory sensitivity can last as long as you have more CO in your tissues than your blood.

We have not verified these recommendations and observations. They represent the view of “Albert” and may differ from those of others with specialized knowledge in the field.

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