I did not think about my dryer vent for the first three years I lived in my apartment. Not once. The dryer worked fine. Clothes came out warm. What was there to think about?

Then a friend — a firefighter — came over for dinner. He walked past the laundry closet, paused, and said, “When did you last clean that vent?” The look on his face when I said “never” was enough to make me order a cleaning kit on the spot.

Dryer vents cause about 2,900 house fires every year in the US, according to the National Fire Protection Association. The number one cause? Built-up lint. The number one reason people do not clean them? They do not know they need to.

Signs Your Vent Needs Cleaning

• Clothes take more than one cycle to dry completely
• The outside of the dryer gets hot to the touch during a cycle
• You smell something burning — even faintly
• The vent hood flap outside does not open when the dryer is running
• It has been more than a year since you last cleaned it

How to Clean It Yourself

1. Unplug the dryer and pull it away from the wall. If it is gas, turn off the gas supply too.
2. Disconnect the vent hose. It is usually held on by a clamp or just friction-fit. Have a vacuum ready — lint goes everywhere.
3. Vacuum what you can reach. Both ends of the hose and the dryer exhaust port.
4. Use a dryer vent brush kit. These cost about $15 at any hardware store. The flexible rod attaches to a drill and spins inside the vent pipe, knocking loose all the lint you cannot reach.
5. Clean the exterior vent hood. Go outside and make sure the flap opens freely. Birds sometimes nest in there.
6. Reconnect everything and test. Run the dryer empty for 10 minutes to blow out any loosened debris.

The whole job takes about 30 minutes. I now do it every spring when I change the smoke detector batteries. Both things protect my house from fire. Makes sense to do them together.