Two basic types of smoke hoods exist, both equipped with exhaust fans. One sucks the polluted air out of the kitchen into the great outdoors, as a fireplace chimney does. The other — a less efficient device — simply filters and recycles the adulterated air in your kitchen. Both reduce grime buildup in your kitchen, minimizing the need for elbow grease and redecoration.
According to the results of a study conducted by the Lawrence Berkeley National Laboratory in California, there seems to be an even stronger reason for having a smoke hood, at least in restaurants where a clutch of ovens bake or roast continually. The researchers found that oven exhaust can contain excess levels of nitric oxide and nitrogen dioxide (both can create respiratory disorders), vinyl chloride (a cancer-causing agent), and carbon monoxide (capable of producing headaches, nausea, and death).
Most homes have a smoke alarm in or near the kitchen, but few have a carbon monoxide detector to sound an alarm when it reaches a precarious level. Unlike smoke, carbon monoxide is invisible and odorless.