It had been such a long week and all I wanted was to sleep in during the weekend so I could rejuvenate my physical and mental strength. I got home, made some delicious tacos, took a shower, had dinner, and settled down on the sofa to watch an episode of my favorite TV series. It was not unusual to drift off to sleep before the first ten minutes. I was out for close to an hour and when I awoke, I felt something was not right. I tried to get up but my head felt heavy and my legs could not carry my weight. On seeing this, I tried to calm myself and called an ambulance. I was in the hospital for three days. The doctors said it was carbon monoxide poisoning. It turns out that the HVAC ducts were leaking and I had not gotten round to scheduling the cooling expert for duct sealing. During typical operation, the HVAC system releases combustion gasses like carbon monoxide through its ventilation systems. The leaking vents caused back-drafting, which is where these gasses are pulled back into the house instead of being expelled outdoors. I have a heat pump and recently got a new air conditioning system, the mini-split air conditioner. To integrate these two systems in different parts of the house, I also have a zone control system that evens out the temperatures. The cooling specialist did a comprehensive air conditioner tune-up to find out whether there were any additional issues. They also check the thermostats and temperature controls in the different rooms. I also found out from the new contractor that to increase the indoor air quality, you need to regularly service the system. Many HVAC businesses usually provide a complete maintenance program.