Dryer exhaust vents are major sources of fires. Flammable lint is produced in the drying process and the buildup of such lint can become a serious fire hazard. The dryer vents in laundry rooms and residential structures should be thoroughly cleaned at least once a year. Not only can dryers become a fire hazard with the build up of lint, but they can also become a flood hazard. Moisture can get trapped inside the duct and pool there. This is most common, but not limited to, high rise construction. Some dryer ducts will hold up to five gallons of duct rotting water. In addition to dryers being a fire and flood hazard if not annually cleaned, a clogged dryer vent could force the dryer to increase workload up to ten times the regular load. In some cases, the dyer duct's warm air attracts birds that build nests in or around the emission hole on the wall outside. Birds may abandon their nest, leaving the straws and mud they used to build the nest, which in turn blocks the airflow. To prevent this type of blockage, protect the hole with mesh and have the air duct and dryer duct professionally cleaned at the same time.

The U.S. Consumer Product Safety Commission estimates that in 2003, clothes dryers were associated with 15,600 fires. These fires resulted in 20 deaths and 370 injuries. As mentioned earlier, lint builds up in the dryer or in the exhaust duct. This lint can block the flow or air, cause excessive heat build-up, and creates a fire risk.

According to the Consumer Product Safety Commission, there are steps homeowners or businesses can take to help prevent dryer fires:

  • Clean the lint screen/filter before or after drying each load of clothes. If clothing is still damp at the end of a typical drying cycle or drying requires longer times than normal, this may be a sign that the lint screen or the exhaust duct is blocked. In this case, the dryer duct should be professionally cleaned, ensuring that a thorough and quality job has been performed.

  • Clean the dryer vent and exhaust duct periodically. Check the outside dryer vent while the dryer is operating to make sure exhaust air is escaping. If it is not, the vent or the exhaust duct may be blocked. Again, a professional should be called to ensure a proper cleaning job is carried out.

  • Clean behind the dryer, where lint can build up. Have a qualified service person clean the interior of the dryer chasses periodically to minimize the amount of lint accumulation. Keep the area around the dryer clean and free of clutter.

  • Replace plastic or foil, accordion-type ducting material with rigid or corrugated semi-rigid metal duct. Most manufacturers specify the use of a rigid or corrugated semi-rigid metal duct, which provides maximum airflow. The flexible plastic or foil type duct can more easily trap lint and is more susceptible to kinks or crushing, which can greatly reduce the airflow.

  • Take special care when drying clothes that have been soiled with volatile chemicals such as gasoline, cooking oils, cleaning agents, or finishing oils and stains. If possible, wash the clothing more than once to minimize the amount of volatile chemicals on the clothes and preferably hang the clothes to dry. If using a dryer, use the lowest heat setting and a drying cycle that has a cool-down period at the end of the cycle. To prevent clothes from igniting after drying, do not leave the dried clothes in the dryer or piled in a laundry basket.