Dryer Vents and IAQ

Dryer vents that are not properly maintained can lead to Indoor Air Quality issues.
Dryers have a tendency to shake, rattle and even bounce around a bit. All of that can cause your vent to become loose, perhaps even fall off, which means all of the "Drying" air is being released into your indoor air.
Also, because a dryer removes moisture from clothes there is a possibility of mildew and mold buildup. The lint that is produced from drying clothes is also somewhat heavy and can accumulate anywhere along the way in the dryer vent, which overtime not only increases the possibility of those building up, but constricting air flow, which increases drying time, reduces your units efficiency but also can be a fire hazard.
Dryer vents service is one of the things that John's Duct Cleaning can do for you. It is suggested that a dryer vent cleaning be done on an annual basis at least.
Someone once said," An ounce of prevention is worth a pound of cure."