Affinity of hemoglobin to CO is 240 times than that to O, and since Hb is responsible for carrying and transporting oxygen that makes CO poisoning really dangerous since it takes oxygen place and prevent it from reaching vital organs.
It's more popular that carbon monoxide poisoning occurs in winter when using heaters, yet I'm not sure if that's the situation in all the world or just here.
Thanks for your contribution dear. Using of heater and fossil fuels, smokes cause carbon monoxide poisoning. Generally the situation is all over the world although many countries are applying measure of preventing this.