Dryer lint is a very combustible substance that builds up in the venting system leading from your dryer, causing a severe fire hazard. The most commonly used vent is made with ribbed plastic to make it easier to route the hose around corners and through walls. This design traps lint in the hose, which builds up over time to dangerous levels. (The plastic of the hose itself is also combustible and produces dangerous fumes when burned.) A dirty vent system can't carry as much water vapor, so it takes much longer to dry your clothes. This wastes both time and energy. You can save money by cleaning your dryer vent hose regularly.