Christmas trees, which many people started buying last weekend, look and smell wonderful, but fire officials warn that a dry tree is like having an explosive in the living room.

“Once it gets dry, it’s basically like having gasoline in your house,” said Everett fire inspector Klaus Janssen. “When trees get dry, they just become more and more combustible.”

Each year, more than 32 million homes nationwide will decorate with a real Christmas tree, according to the National Fire Protection Association. And each year, on average, trees are blamed for about 210 fires that kill 24 people and cause about $13.3 million damage.

To avoid fire risks, people should cut an inch of the bottom of a newly purchased tree and immediately put it in water, Janssen said. Add water at least once a day.

“Typically, with some of the tree stands out there, it may mean (watering) more often,” he said.

For each inch of diameter, add a quart of water a day, Janssen said. That means for a four-inch diameter tree — or about a six-foot-tall tree — people need to add about a gallon of water.

If the tree starts to dry out, get rid of it, Marysville Fire spokeswoman Stephanie Price said.

A dry tree can fully ignite in a matter of seconds, she said.

A good test to see if the tree is dry is to use fingers to brush the needles. If they fall off or seem brittle, the tree is a fire bomb, she said.

Trees purchased right after Thanksgiving should be tossed right after Christmas, experts said.

Keep in mind that strings of lights, which cost about $3, can fail after sitting in storage for a year, Price said. Check the lights before putting them on the tree.

Never put candles or other heat sources near the tree and keep exits clear, Janssen said.

“Christmas trees are a tradition. It’s part of the holiday that a lot of people enjoy,” Price said. “If you’re having a tree for the holidays, you’ve got to keep it well-watered.”

Reporter Jackson Holtz: 425-339-3437 or jholtz@heraldnet.com.

Tree safety

If not properly cared for, Christmas trees can pose a dangerous fire threat, experts said. Here are some simple tips to stay safe and avoid fire risks:

n Use fresh trees and cut about an inch off the bottom when purchased.

n Water the tree several times a day. For each inch of diameter, add one quart of water daily.

n Use only UL-listed lights and double-check to make sure lights are in good working order before stringing onto the tree.

n Never use electrical lights on a metal tree.

n If using a fake tree, make sure it’s treated with fire retardant.

n Never burn candles on or near a tree.

n Keep trees away from all heat sources and exits.

n When a tree starts to drop needles, throw it away. Don’t store trees against your home or garage.

n Never leave holiday candles, or any candles, unattended.

Inside: For a list of Christmas tree farms, see Page B8.