Eight days before Austin police Sgt. Zachary LaHood was poisoned in his patrol car, city staffers had returned his Ford Explorer Police Interceptor to the road after addressing manufacturer worries of carbon monoxide leaks.

Ford Motor Co. had issued a "technical services bulletin" — a notice that they are aware of a possible issue in a car — to the city about the car. By March 10, the company had serviced the SUV and told the city it was ready for the road.

A few hours into his night shift on March 18, LaHood became seriously ill with dizziness, headaches and nausea and says he almost hit a bus before navigating his car off the road. He was treated for carbon monoxide poisoning, leading to neurological injuries, and has never returned to work.

"I’m lucky to be alive, I believe that," LaHood told CBS News, which did a national story on the issue last week focusing on Austin. "And I’m lucky I didn’t kill someone else and their family that night."

WATCH: ‘I almost hit a bus,’ says officer woozy from carbon monoxide

Since LaHood’s incident, the Austin Police Department has become a hot spot in what now seems to be a national problem with carbon monoxide in Ford SUVs made for law enforcement. Since the beginning of the year, Austin police have complained of 10 incidents involving carbon monoxide in department vehicles, with LaHood believed to have suffered the most significant injuries.

In Newport Beach, Calif., an officer — who said he was overcome by fumes — passed out behind the wheel of his SUV and crashed into a tree. An officer in Henderson, La., also blamed carbon monoxide for her accident, saying she blacked out and flipped her vehicle.

But Austin’s troubles seem more extensive than those seen elsewhere, and it’s unclear why. Five Austin police officers were recently treated for possible carbon monoxide poisoning over a four-day span that ended last Monday night amid escalating concerns that their city-issued SUVs could be exposing them to the deadly gas.

After LaHood’s accident, the department immediately began installing carbon monoxide alarms in each of the cars, spending about $27,000 on the project, which was recently completed. As they did so, the alarms activated, with more than 40 activations between March and last week.

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All 40 were taken to Ford. Of those that came back, 10 have been returned to Ford by the city because of ongoing concerns. Four have been returned to the road.

Though generally referred to as Ford Explorers, law enforcement agencies use what are technically called Police Interceptor Utility Vehicles. They look like Explorers, but are designed to allow departments to add light bars, radios, consoles and other police equipment.

"We have investigated and not found any carbon monoxide issue resulting from the design of our Police Interceptor Utility Vehicles," Ford spokeswoman Elizabeth Weigandt said. "We know police modify these vehicles, which can contribute to exhaust-related issues. We have provided instructions to help seal these modifications and are ready to inspect any vehicles with this concern."

But Ford Explorers purchased off car lots by the public have had their own problems.

Class-action settlement

Between 2011 and 2015, there have been 154 drivers across the country who reported trouble with their Explorers to the National Highway Traffic Safety Administration, which is now investigating. In those cases, drivers largely complained that their SUVs smelled like exhaust fumes when they accelerated while using the air conditioning.

The greatest number of complaints, 29, came from Florida. Texas was second, with 25. Three of those complaints came from Austin, while two came from Round Rock.

In a 2015 complaint, one Round Rock driver reported that "the fumes have caused headaches, nausea and fatigue. These incidents have occurred during acceleration and sustained highway speeds." The driver’s children could also smell the fumes from the second and third rows of the vehicle, the complaint states.

Ford recently settled a class-action lawsuit out of Florida in which the company agreed to reimburse people across the country for the cost of their repairs.

Carbon monoxide poisoning can cause nausea, headaches, dizziness and other ailments. More serious cases can cause neurological problems, brain damage or death. The gas is tasteless, odorless and colorless, making it nearly impossible to catch without a detector.

When carbon monoxide gets into the blood, it prevents oxygen from spreading through the body, said Chris Ziebell, chief of emergency medicine at Dell Seton Medical Center.

"It basically suffocates you," he said.

Replacing the Crown Vic

The use of SUVs among law enforcement increased when Ford discontinued the Crown Victoria sedan in 2011.

Bill Johnson, executive director for the National Association of Police Organizations in Alexandria, Va., said there are no statistics he’s aware of that show which vehicles are most common among law enforcement, but departments have shifted to SUVs "because they carry more equipment, carry more people."

He said law enforcement officials are likely more susceptible to carbon monoxide exposure than other drivers because their vehicles are left idling while they fill out reports, talk to someone or safeguard traffic.

"Exposing the occupants and, from our point of view, police officer drivers, to poison is a grave concern of ours," Johnson said. "You’re endangering the safety and the lives of our officers."

Austin began transitioning from Crown Victorias to the SUVs about seven years ago, and most of its patrol fleet consists of the Ford Police Interceptor with about 400 units that range in model year from 2013 to 2017.

University of Texas police have about 15 Explorers, while Round Rock police have 57 and Cedar Park 13. San Marcos uses them, too. None of those departments reported any carbon monoxide issues outside of a minor scare in Round Rock.

Ford makes a number of modifications to the Police Interceptors, such as separating the front and passenger areas for transporting prisoners. Once the car is handed over to the city, fleet workers add bumpers and steel to the exterior of the car and decals to make it look like a police vehicle. Other city workers add electronics and other items to the cars such as radios, shotgun racks, emergency lighting, sirens and mounted in-car computers.

Austin police and city fleet workers say that none of the changes should have an impact on their exhaust systems.

"We follow industry best practices when we make modifications to the vehicles," city spokesman Bryce Bencivengo said.

The investigation continues

Problems with the Austin Police Department’s vehicles first emerged with LaHood’s case this spring. He was heard on a recently obtained dashboard camera video describing his symptoms to fellow officers.

"I just need fresh air," he said. "I started having headaches, and I can’t breathe. … I almost hit a bus. It scared the (expletive) out of me. My heart rate is low. I thought I was having heart attack. I didn’t know what was going on."

LaHood is now suing Ford.

Austin’s additional cases prompted police to renew their efforts to resolve with Ford what might be causing the problem. But authorities added that they are rapidly looking into other emergency measures, such as renting a fleet of vehicles to ensure officers are safe.

City officials recently put together a protocol in which fire officials are dispatched to the car to conduct carbon monoxide readings. Under a new requirement, the SUVs then must be towed to a city garage.

In recent days, the Police Department has developed a contingency plan in case the department decides to immediately stop using the Police Interceptors. It calls for sedans currently assigned to other units, such as the SWAT team and to detectives, that are considered "pursuit-rated," to be used for patrol.

Working with federal highway safety officials, the department also has developed a list of data it wants officers and supervisors to collect, including the outside temperature and whether the air conditioning was running, to see if they can identify any patterns that might lead to a cause of the leaks.