Until senior Liz Hayes got her furnace checked by the city health inspector last week, there was no indication it had been leaking a dangerous toxin into the air for more than a day.
Carbon monoxide poisoning, which causes flu-like symptoms including nausea, headache and dizziness, is
the No. 1 cause of accidental poisoning deaths.
That toxin was carbon monoxide, an odorless, colorless and tasteless gas that could, at worst, result in death.
It's a scenario that rarely plays out, but carbon monoxide levels still should be monitored carefully, environmental health specialist Tate Zurbuchen said.
"Carbon monoxide is kind of a dangerous one," he said. "Our tip would be to purchase a carbon monoxide meter … which would give you an idea if you have a problem."
There were 35 residences and four public buildings investigated by the city health department last year, Zurbuchen said, though only a few were found to have high carbon monoxide levels.
In the affected homes, the high levels were caused by faulty space heaters and one was due to a malfunctioning gas furnace.
"Most of our calls come from people whose meters went off, and most of the time (those were) false positives," Zurbuchen said.
In Hayes' case, the temperatures outside began to dip and she still was without a working furnace. The existing furnace was old and would cost too much to operate, she said.
She said she called her landlord with concerns over the furnace's age and reliability, and after his slow response, called the city health inspector.
"We wanted to make sure we were going to be safe. That was our main concern," Hayes said. "It was a low amount but it was enough that we could potentially be feeling dizzy and sick."
Zurbuchen added anything that seems to be out of adjustment on heaters or furnaces should cause concern for the resident.
Some of the first symptoms of carbon monoxide poisoning are a variety of different flu-like symptoms, Zurbuchen said, such as nausea, headaches and dizziness.
Other health effects might be shortness of breath, chest pain or blurred vision.
"Senior citizens or young children may be particularly sensitive," Zurbuchen said. "They may experience these problems earlier than the average person."
Hayes and her roommate did not experience any symptoms since it had not been emitting very long.
Carbon monoxide is the No. 1 cause of accidental poisoning deaths, according to the Journal of American Medical Association. CO meters cost around $20.
Zurbuchen and Hayes advised working with landlords on making sure everything is in order and to ask questions upon move-in.