Milwaukee, WI – Winter officially begins today as Wisconsin observes the Winter Solstice, the shortest day and longest night of the year. While the solstice marks a seasonal turning point and the gradual return of daylight in the weeks ahead, safety officials warn it also signals one of the most dangerous times of the year inside homes—when carbon monoxide exposure becomes more likely.
The longest night of the year often coincides with frigid temperatures across Wisconsin, leading residents to rely heavily on furnaces, boilers, fireplaces, wood stoves, and space heaters. In areas impacted by heavy snow or ice, generators may also be used during power outages. With windows closed and homes sealed tightly against the cold, ventilation is reduced, allowing carbon monoxide to build up indoors.
Carbon monoxide is a colorless, odorless gas produced when fuel-burning appliances do not burn completely or are not properly vented. Because it cannot be seen or smelled, it is widely known as the “invisible killer.” According to the Centers for Disease Control and Prevention, carbon monoxide poisoning sends tens of thousands of Americans to emergency rooms each year, with winter months posing the highest risk.
Medical experts warn that carbon monoxide poisoning disables far more people than it kills, often leaving survivors with long-term neurological or cognitive damage. Early symptoms may include headaches, dizziness, nausea, fatigue, and confusion. As exposure continues, symptoms can worsen to chest pain, vomiting, impaired coordination, loss of consciousness, and death. Because these warning signs can resemble flu-like illness or general winter fatigue, many people do not recognize the danger until exposure becomes severe.
Fire departments across Wisconsin consistently caution that long overnight periods—such as those experienced during the Winter Solstice—are especially dangerous. Extended darkness means heating systems may run for hours without interruption, fireplaces and wood stoves may be used more frequently, and vehicles are sometimes left idling in garages to warm up. Running a vehicle in an attached or enclosed garage, even briefly, remains one of the leading causes of fatal carbon monoxide exposure.
Safety officials urge Wisconsin residents to ensure carbon monoxide detectors are installed on every level of the home and outside sleeping areas. Alarms should be tested regularly, and batteries replaced as needed. Residents are also advised never to use grills, camp stoves, or fuel-powered heaters indoors, to keep exhaust vents and chimneys clear of snow and ice, and to schedule annual inspections of heating systems.
If a carbon monoxide alarm sounds, experts say residents should leave the home immediately and call 911 or the local fire department from outside. Anyone experiencing symptoms of carbon monoxide exposure should seek emergency medical care without delay.
As Wisconsin moves through the longest night of the year, safety officials say the Winter Solstice is more than a seasonal milestone. It is also a reminder that carbon monoxide—the invisible killer—poses a serious but preventable danger when awareness and preparation fall short.
