Lisa Alvarez didn’t realize how close she’d come to a dangerous situation until she was driving home from the hardware store one recent day. Now she’s become a poster child for carbon monoxide poison education in Novato — and gladly.

Alvarez, who lives on Novato’s west side, got ticked that her carbon monoxide detector went off one day last month.

“I got irritated, unplugged it and threw it in the garage to shut it up,” she said.

She didn’t realize that the groggy, dizzy feeling she had might be tied to a carbon monoxide problem in her house.

She went to Pini Ace Hardware and talked to Russ Young about the “broken” detector and possibly to buy a test kit. After hearing the story, including that she hadn’t felt well that morning, Young suggested that Alvarez forget about buying anything and instead call Pacific Gas and Electric Co. to get the house checked. Alvarez took the advice.

“I’m driving home and I’m thinking to myself, wait a minute, I feel 100 percent better than when I was at the house,” Alvarez said. “Then the light bulb went off, and I was going through the whole sequence in my mind.”

She called PG&E right away and a technician came out to the house quickly. The meter showed high levels of carbon monoxide.

“My house was poison,” she said.

She retraced her steps and remembered what had happened: When she replaced the filter in her furnace, the door of the furnace in her hallway closet slipped off and wasn’t probably back in place, causing carbon monoxide to leak out.

It’s a typical story, says Novato Fire Marshal Bill Tyler. He heard the story from Alvarez’s father, retired Novato fire captain Fred Pfeifer, who lives in San Rafael. Although retired about 13 years now, Pfeifer had bought a bunch of detectors and urged his daughter to install them in her house.

 “Fred is a stickler about smoke detectors,” Tyler said. “When the new law came out about carbon monoxide detectors, he bought a bunch of them and went to his daughter’s house to make sure she put them up. In this case, CO started to fill the house rather than vent properly.”

Tyler credits Young for giving some outstanding advice.

“What he was hearing was somebody describing CO poisoning,” he said, “so he told her not to go back into her house and to call PG&E. In my mind, he’s a model employee who understands CO and how it works. She could have gone back in and not made it out again.”

Alvarez’s children already were out of the house, but some pets were inside. They were brought to safety and the problem was corrected by PG&E.

Once it was all over, Alvarez was overcome with emotion. She told Tyler she was embarrassed because she was the daughter of a fire captain and probably should have recognized the issue. But Tyler assured her that it was a great lesson learned and nobody was injured.

“She thought her dad was a pest for putting those detectors in, but in the end she was glad he did it,” Tyler said.

“Thanks, Dad, for saving my life,” Alvarez said. “And Russ, you’re the man.”