ANCHORAGE, Alaska (AP) — Mount Redoubt is getting under the skin of Alaska, and it’s not just the irritation caused by volcanic ash.

For residents of Alaska’s largest city, living near an active volcano means sometimes wearing air-filtration masks and stretching panty hose over the air intake of cars and trucks.

The volcano also brings daily uncertainty about whether it will blow and, if it does, where the ash will go.

‘‘I would like it to have a big boom and get it over with,’’ said Brad Sandison, a retired truck driver and avid cyclist who carries a face mask and goggles whenever he rides just in case the volcano starts spewing ash.

The mountain 100 miles southwest of Anchorage tends to erupt every decade or so and belch ash for months. Geologists have recorded at least 19 eruptions since March 22, including one on Saturday.

So far, Mount Redoubt’s almost daily ash clouds have canceled hundreds of airline flights, reduced the number of shipments flowing through a huge FedEx cargo facility and cut shipments of fresh Alaskan seafood.

People with breathing problems also face health risks.

Respiratory patients should avoid being outdoors when the ash is falling, said Dr. Teresa Neeno of the Allergy, Asthma and Immunology Center of Alaska. Those who must be outside should wear a mask.

Lin Walters of Nikiski makes sure her 81-year-old mother, who has severe asthma, is wearing a face mask whenever the volcano erupts.

‘‘When the volcano blows, she has to put on her mask because we don’t know which way the ash is falling,’’ Walters said. ‘‘She has a whole box of them sitting beside her recliner.’’

The last time Redoubt erupted was late 1989 and early 1990. Eruptions went on for four months. One ash cloud undetected by radar knocked out all four engines of a jetliner, which descended 13,000 feet before its engines could be restarted. The plane landed safely.

Seismologists at the Alaska Volcano Observatory do not expect the volcano to erupt violently. It usually burps ash and gas as molten rock forms a dome in the mountain that eventually collapses, resulting in eruptions. Then the process begins again.

Scientists have no way to predict when the volcano will erupt and what direction the wind will be blowing when it does.

However, researchers at the Alaska Volcano Observatory have come up with a volcanic ash tracking model that is updated online every three hours. Users can click on the height of the ash plume and then view a model of where the ash cloud is likely to go in one-hour increments.

The National Weather Service also issues ash advisories in much the same way as it does with storms and floods.

Since the latest eruptions began, Alaska Airlines has canceled 300 flights, affecting an estimated 20,000 passengers.

Joe Tacker of Monterey, Calif., was trying to get to Anchorage last weekend to help judge a two-day dog show. Then Redoubt blew several times.

After two other flights were canceled, Tacker got on a third flight out of San Jose. While waiting for takeoff he checked his cell phone messages one last time. With a flight attendant pressuring him to put his phone away, he clicked on the last message. It informed him that the dog show had been canceled because of the volcano.

‘‘I told the stewardess ’Stand back,’ and I got up and grabbed my stuff from out of the top and took off down the aisle,’’ Tacker said.

‘‘You make a real effort to get to Alaska for the dog shows because everyone is so nice up there,’’ Tacker said. ‘‘Also, you want to get some good fish.’’

As far as fish, Tacker probably would have been disappointed, especially if he wanted to ship some home.

When the volcano forced a 20-hour shutdown last weekend of the Anchorage airport, the shipping system became clogged with delayed cargo.

‘‘It kind of created a domino effect with all the cargo stations around the state and in Seattle and Portland,’’ said Dannon Southall, wholesale salesman for 10th and M Seafoods in Anchorage. ‘‘The wind shifts every day.’’

Because thousands of displaced passengers were bumped from canceled flights, airlines have less space for boxes of crab, salmon, cod and halibut. That cargo space is now taken up with luggage that needs to be returned to its owners, Southall said.

The volcano calmed down for much of last week, but then produced another large eruption Saturday. Radar indicated a plume of volcanic ash rose 50,000 feet into the sky, making it one of the largest eruptions since the volcano became active on March 22, the weather service said.

‘‘The second you get that false sense of security, it is going to go boom,’’ Southall said before Saturday’s burst.

Instead of moving cargo through Anchorage, FedEx is diverting most cargo through its hub in Oakland, Calif., with one or two flights also going to Seattle.

Normally, the company operates 21 flights in and out of Anchorage each day. That has been reduced to three, spokeswoman Sally Davenport said.

In an effort to shield their engines from volcanic ash, some motorists place pantyhose over the air intake. But ever since a layer of ash descended on Nikiski, 60 miles southwest of Anchorage, Dan Ward has had a steady stream of customers complaining about car trouble.

A look under the hood usually solves the mystery: They placed the panty hose in the wrong place.

‘‘Just get a good quality air filter and keep one in the car and change it every so often,’’ said Ward, owner of Dan’s Automotive.

Wayne Kvasnikoff, plant manager for the Seattle-based Ocean Beauty Seafoods fish-processing plant in Nikiski, is glad the plant is closed this time of year. The ash that coated the town in gray last Saturday will still be there when the plant reopens for the summer salmon season.

The ash will require a rigorous spring cleanup, he said.

‘‘We will do it the same way they have in the past, with large water hoses,’’ Kvasnikoff said. ‘‘We will wash it out.’’