Carbon monoxide poisoning or Covid-19? Here's how you can tell

Installing a carbon monoxide detector is the best way to prevent poisoning in your home.

(CNN)As the Northern Hemisphere heads into winter, whether a fever and cough mean the flu or Covid-19 is a nerve-racking guessing game. There is, however, a silent killer that causes similar symptoms and could be lurking in your home.

Carbon monoxide is a colorless, odorless gas that's produced when a fossil fuel — coal, crude oil or natural gas — is burned by furnaces, portable heaters, vehicles, stoves, grills, gas ranges or fireplaces.
Breathing in too much of it can poison you, leading to symptoms including headache, upset stomach, dizziness, weakness, vomiting, chest pain and confusion, according to the US Centers for Disease Control and Prevention — mimicking the symptoms of the flu or Covid-19.
Inhaling high concentrations can make you pass out or kill you, especially if you are sleeping, drunk or belong to a group that's at high-risk for serious illness and death from different diseases and exposures. Carbon monoxide can also poison your pets.
    "Influenza and (Covid-19) hijack the cells, mostly in lungs, where they reproduce and that's where the main damage is often done" and where symptoms stem from, said Dr. Jeremy Brown, an emergency care physician and author of "Influenza: The Hundred-Year Hunt to Cure the Deadliest Disease in History."
    Carbon monoxide, on the other hand, poisons people by hooking onto hemoglobin, the protein in red blood cells that carries oxygen from the lungs to the body.
    "The carbon monoxide comes along and kicks the oxygen off the hemoglobin," Brown said. "What you start to have are signs of a lack of oxygen."
    Over 20,000 Americans annually visit the emergency room for carbon monoxide exposure, over 4,000 are hospitalized and over 400 die. Since many are now at home almost 24/7, it's certainly possible that emergency doctors will "see more carbon monoxide exposure than usual" — especially if we have a harsh winter and rely more on heating, Brown said.
    Inadvertent poisoning "can be stopped by practicing safe behaviors," said Scott A. Damon, health communication lead at the CDC's Asthma & Community Health Branch.
    Read on to learn the common causes of exposure, how you can prevent it, how to know what's causing your symptoms and the potential treatments.

    Preventing exposure and poisoning

    Carbon monoxide exposure is the byproduct of incomplete combustion, Brown said — when the oil in appliances or vehicles is heated but doesn't burn completely. Blocked ventilation systems and running portable generators in confined spaces or on boats without proper ventilation can also lead to buildup.
    Additionally, "these are the months when people may warm up a vehicle inside an attached garage, which is extremely dangerous" even with the garage open, Damon said. That's because the fumes can seep into your house.
    The most important way to be able to tell whether symptoms are from carbon monoxide exposure is to install a carbon monoxide detector, Brown said. Since carbon monoxide sinks, having one in your basement is critical, but the potential for exposure on every floor means you should also have detectors installed in the main living areas and in or near bedrooms so you can be woken up by an alarm while sleeping.
    Install and test battery-operated detectors and check and replace batteries twice a year when you change your clock, the CDC recommends. And consider buying a detector with a digital readout that also shows the level of concentration in the home.
    "Check the manufacturer's instructions on when to replace the detector itself," Damon said.
    Your smoke detector should indicate whether it can also detect carbon monoxide. Levels higher than one to 70 parts per million can cause symptoms.

    What's the source of your symptoms?

    If you or your family are experiencing even mild symptoms and carbon monoxide poisoning is possible, your best bet is to get everyone to a safe environment and get checked out by a medical professional, Brown said, especially if you belong to a high-risk group.
    But could it be the flu? Having received an influenza shot doesn't guarantee that you don't have the flu since flu vaccines, even when they match the viruses circulating, reduce the risk of illness by 40% to 60%.
    A process of elimination will allow emergency care doctors to figure out if you have Covid-19, the flu or carbon monoxide poisoning, Brown said.
    "One of the ways in which carbon monoxide differs from (Covid-19) and from influenza is that if you step outside and get some fresh air, your symptoms will slowly dissipate" over the next several hours if your exposure was minimal, Brown said. If someone feels better outside but symptoms creep up at home, that could be a sign of poisoning.
    If it's possible that you've been exposed in your home, a doctor can administer a blood test to measure your carbon monoxide level, Brown added.

    Potential treatments

    If a doctor suspects poisoning, Brown said, you'll receive an oxygen mask that would deliver about five times more oxygen to your body than is available in the atmosphere. The doctor would then keep an eye on you for up to several hours and check your carbon monoxide level until you can be discharged — "with the instructions not to return to the place where they were ex