Landlords must now install working detectors in their rental properties.
Adele Forbes, from Gilfach in Bargoed, has been campaigning for stricter rules on home security systems for almost two decades.
Her son McCauley, 5, and her grandparents, Gloria, 69, and Patrick, 71, died at their home in October 2005 after a chimney in the home became blocked.
Now landlords in Wales must fit carbon monoxide detectors in addition to fire alarms, otherwise their property will be considered uninhabitable.
Records show that between 20 and 60 people die each year from carbon monoxide poisoning, known as the “silent killer,” and thousands more are treated in hospitals.
Carbon monoxide can be produced by fire and appliances that burn gas, wood, oil, or coal. It can kill people in minutes if it builds up to lethal levels very quickly indoors.
It can also be toxic in small amounts if people are exposed to it over time.
People often feel better when they leave the indoor area where the heat source is located and then tend to feel worse when they return.
Symptoms of carbon monoxide poisoning include:
Symptoms can come and go. They may get worse if you spend time in an affected room or building and get better if you leave the house or go outside.
There are now concerns that safety corners are being cut as consumers are tempted to keep energy bills down by using appliances like grills to cook indoors or heat their homes.
There’s also a concern that people will put off maintaining equipment if they can’t afford it.
Adele recalled her family’s death and told Latest Page News she hoped people would take notice and make sure they had burglar alarms in their homes.
Her son McCauley went to live with her grandparents on October 25, 2005. She picked him up the next day when she saw the worst happen.
She said: “I entered the property and you could smell this strong sulfur smell, I know carbon monoxide has no smell but it was the old coal boiler and you could just smell this strong sulfur eggs smell.
“When we walked in, my grandfather was on the kitchen floor and McCauley was upstairs in bed and so was my nan.”
Adele told Latest Page News when she realized they had died it was terrifying and she couldn’t really process what was happening.
“It took three to four hours for firefighters to confirm they were all dead. That night it happened to other people, not us.”
“It’s something you would read about in Take a Break magazine, someone’s sad story, but that sad story then happened to us.
“I lost a big part of my life that day.”
Adele said she didn’t know much about carbon monoxide poisoning beforehand, but thinking back, her grandma was ill with symptoms related to the gas.
“I know it built up over a period of months which then brought me back to thinking about the past six months, my grandma has always been unwell.
“My grandma spent a lot of time in the house, my grandfather was always going back and forth in the garden. She was always sick. So if I would go down and sit with my grandma for a few hours, I would feel sick all the time and it was a joke when my grandfather said there was something wrong with that house.”
“When I went home after about an hour I felt okay but now I know what it was and because my nan was so ill with her mental health the entire time she was on a lot of medication and so The Doctor would.” always trace it back to something like that.”
A coroner’s report indicated that the family would have died between 11:00 p.m. and 3:30 a.m. that evening in October.
That night, the carbon monoxide produced in the house was so strong that it caused her death. Adele said she now hopes people will hear her story and take carbon monoxide very seriously.