https://completemarkets.com/Article/article-post/1506/CARBON-MONOXIDE-POISONING/
... although carbon monoxide has no telltale odor, it may mix with gases which do have an odor. Thus, the smell of other gases doesn't mean an absence of carbon monoxide. ARE YOU LIKELY TO BE POISONED? If you have a heart condition, your condition may be aggravated by carbon monoxide. Ingestion of barbiturates and alcohol may increase the gas' health effects. Furthermore, smokers will have higher carboxyhemoglobin than non-smokers, and therefore face higher risk from carbon monoxide exposures on the job. Harmful levels of carbon monoxide are a potential danger to: acetylene workers, blast furnace workers, boiler room workers, brewery workers, carbon black makers, coke oven workers, customs workers, diesel engine operators, dock workers, garage mechanics, metal oxide reducers, miners, organic chemical synthesizers, petroleum refinery workers, pulp and paper workers, steel workers, toll booth and tunnel attendants, and warehouse workers. HOW DOES CARBON MONOXIDE HARM YOU? Large amounts of carbon monoxide can kill in minutes. The more carbon monoxide in the air and the longer you are exposed to it, the greater the danger. Any one or more of the following symptoms can signal carbon monoxide poisoning: headaches, tightness across the chest, nausea, drowsiness, inattention or fatigue. As the amount of carbon monoxide in the air increases, more serious symptoms develop such as lack of coordination, weakness and confusion. The poisoning can be reversed if caught in time. But even if you recover, acute poisoning may result in permanent damage to the parts of your body which require a lot of oxygen, such ...