WORTHINGTON  - When Mark and Maria Thier envisioned Mark’s snowmobiling trip to West Yellowstone, they had in mind a fun few days of learning advanced skills, taking in some beautiful scenery, and enjoying a popular sport with friends.


What Mark got was a trip to the hospital and a lingering health scare that he and his wife will never forget.


“I went out west to a snowmobiling school,” Mark narrated humbly, not revealing until later that it was an advanced class, teaching skilled maneuvers while going up and down rugged Montana hills. “We got there and the group staying in the cabin before us hadn’t left yet, and they were short on rooms so I decided to stay out in our RV.”


Mark had driven their RV, a Toter Home (sometimes spelled as one word), most of the night to reach their destination and he was tired. But no one else in his party - eight of them all together - was yet ready to settle down. So Mark made the logical choice to go and sleep in the RV - something he had done many times before - and had, in fact, just the previous night.


It was cold that night, with temperatures hovering around 25 below zero, and calm; there was no wind at all. Because of the temperature, Mark turned on the heater. He opened the door of the heater compartment as he always did, so as to ensure proper ventilation.


And then he went to sleep.


The next morning is a bit of a blur for Mark. He woke up after sleeping for close to 12 hours. He woke up … but he couldn’t get up.


“I thought I had the flu,” Mark revealed. “I was so sick. I couldn’t pick myself up to do anything. I was throwing up. I was so ill I couldn’t move. I had never felt like that before. I had no depth perception, could barely walk, had no vision.”


In the midst of his misery, Mark managed to make two phone calls. He called his buddies inside the cabin, and he also called his wife back home in Worthington. That call he remembers, the other one doesn’t recollect at all.


“I told them I needed to go to the hospital,” Mark said. “So someone came out to check on me. They thought it was maybe altitude sickness, which I’d had once before, but this was different than that.”


Ultimately, they agreed to take him to the hospital, an hour away in Big Sky.


“At the hospital they suspected right away what had happened but we didn’t believe them,” Mark explained. “They tested me for flu and other things, said maybe I had a touch of pneumonia. Then they got the results from the blood test and it said that my CO levels were ‘slightly elevated.’ They put me on oxygen (but not in a hyperbaric chamber) for four hours and sent me home. I was back at the cabin by 7 o’clock.”


Mark felt “quite a bit better” that evening, but he was tired - “always tired,” he described. He didn’t go snowmobiling at all, and stayed in the cabin resting for the remainder of the trip.


As he hung around the cabin he discovered, while investigating the Toter Home, that one of the windows had been just barely cracked open. This made him realize that, given the complete lack of wind (meaning that the carbon monoxide had nowhere to go and just hung in the air outside the RV and - ultimately - inside it, too, through the tiny opening in the window) that that was indeed the most likely answer to his illness. The hospital’s suspicions were correct: he had carbon monoxide poisoning.


Well, that was the answer and, Mark figured, that was the end of the story. He and his friends piled back into the RV for the return trip, and Mark felt well enough to even do some driving.


“I was (still) exhausted, always exhausted,” Mark described. “But I drove part way back. We stayed overnight in Sheridan, Wyo., in a hotel - not the RV,” he laughed. “We got back Tuesday evening (the 17th of January).”


At this point in the narrative, Maria took over the story.


“He was good on Tuesday night,” Maria continued. “He ate supper with us and was doing quite well. The next morning he drove the kids to Luverne at 5:30 a.m. to go skating and then went to work until 11 when he called and said he was going to go home and lie down for a while.”


“I didn’t feel right,” Mark agreed. “Had a constant headache. I continued my regular routine, but then I called Maria that evening when she was in Luverne with the kids and said that I would go in to the doctor in the morning if I didn’t feel better.”


When Maria got home that evening and discovered that Mark could barely walk up and down the stairs, she decided it was time to take him to the emergency room.


“The doctors and nurses here were fabulous,” Maria said. “They were proactive and did everything they could for him. They asked if he had been put into an oxygen chamber - he hadn’t. That could have prevented the issues that Mark was now dealing with.


“They could see his records from Montana, and saw what his carbon monoxide levels were when he was there. Normal CO levels range from .5 to 1.5,” Maria revealed, “Mark’s was 27 - and that was after an hour drive to the hospital.”


After giving Mark a cocktail for his headache, which allowed him to sleep, they ordered some more tests including a brain scan, which came back perfectly normal, and a heart scan, which came back showing that things were not normal at all. That test revealed that, as a result of the CO poisoning and subsequent lack of oxygen, Mark had suffered a heart attack.


According to Mayo Clinic’s web page, “Carbon monoxide poisoning occurs when carbon monoxide builds up in your bloodstream. When too much carbon monoxide is in the air, your body replaces the oxygen in your red blood cells with carbon monoxide. This can lead to serious tissue damage, or even death.”


The web page continues, “Depending on the degree and length of exposure, carbon monoxide poisoning can cause permanent brain damage and damage to your heart, possibly leading to life-threatening cardiac complications.”


Mark is proof that, “life-threatening cardiac complications” can indeed occur. Thankfully, however, after an echocardiogram and a stress test, doctors have told Mark and Maria that no permanent damage occurred and he shouldn’t be at any more risk of cardiac problems than he was before the incident.


Now, barely a month after his scare, Mark is back to his old self with one or two changes in his views about life.


“We have since put a carbon monoxide detector in our RV,” Mark and Maria said, laughing. “And we replaced all of our monitors in our house - they’re only good for about 10 years.”


“It’s such an easy solve,” Maria emphasized. “Just buy a monitor and plug it in. It can save your life.”


“It’s important in fish houses, RVs, your home,” Mark added. “You can get battery-operated ones.”


“You need that alarm,” Maria agreed. “With CO poisoning there is no smell, nothing to hear, no taste. You just go to sleep.”


“It’s important to recognize the symptoms,” Mark said. “I just thought I was sick, but it plays havoc with your body. I just knew it felt like nothing I’d felt any other time.”


“We’re absolutely sure that God was watching over us,” Maria said in closing. “At every point, we definitely had someone on our side.”


And yes, if you’re wondering, Mark admits that he can’t wait to go snowmobiling again.


A few simple precautions to prevent carbon monoxide poisoning, listed below, are included on Mayo Clinic’s web page. See www.mayoclinic.org for more information.


  • Install carbon monoxide detectors.
  • Open the garage door before starting your car.
  • Use gas appliances as recommended.
  • Keep your fuel-burning appliances and engines properly vented.
  • If you have a fireplace, keep it in good repair.
  • Keep vents and chimneys unblocked during remodeling.
  • Do repairs before returning to the site of an incident.