Mark Gongloff: Wildfire smoke is coming for the U.S. again. We’re not ready.

Many Americans were surprised last year when smoke from wildfires hundreds of miles away turned their air toxic. There’s no excuse for anybody to be surprised when it happens again — possibly in just a couple of months.

Canada’s emergency preparedness minister has warned repeatedly that an unusually dry and warm winter, combined with what might be an unusually dry and warm spring and summer, could lead to another terrible wildfire season. “With the heat and dryness across the country we can expect that the wildfire season will start sooner and end later and potentially be more explosive,” Harjit Sajjan said in a press conference recently.

It’s hard to imagine a Canadian wildfire season more explosive than last year’s, which burned a record 15 million hectares (37 million acres), more than seven times the annual average. Dozens of those fires kept burning through the winter, even under the cover of snow. (These are known as “zombie fires,” a phrase that joins “firenado” and “thundersnow” in the growing lexicon of freak-weather terms you wish you’d never heard.)

The end of the latest El Niño weather pattern in the Eastern Pacific, which tends to make much of Canada warmer and drier, could help. But a changing climate has played a much bigger and more durable role: Global heating made last year’s intense fires in eastern Canada more than twice as likely, according to the research group World Weather Attribution. As long as people keep burning fossil fuels and spewing heat-trapping gases into the atmosphere, the planet will warm even more, and wildfires will become more frequent and intense. And this won’t be limited to Canada; The annual average U.S. acreage burned by wildfire has doubled in the past 20 years.

Where there’s fire, there’s smoke, as the saying sort of goes, and wildfire smoke will be one of the most noticeable ways climate change threatens human health in the years to come. It could cause as much as 27,800 U.S. deaths per year by 2050, according to a new study in the National Bureau of Economic Research, with an annual economic cost of $244 billion.

Children, senior citizens and people with asthma and other underlying health issues can be harmed by relatively low concentrations of wildfire smoke. But the stuff is such a toxic stew of chemicals, delivered in particles small enough to enter the bloodstream, that even the healthiest of us should avoid it.

That’s not exactly news to people on the West Coast, where spending long stretches under the tyranny of poison clouds has become grimly familiar. But it caught millions off guard in New York and many other places east of California last spring and summer, when Canadian wildfire smoke temporarily gave American cities some of the unhealthiest air on the planet.

New York officials were accused of waiting too long to warn about the danger when the smoke hit in early June, leaving people exposed and uninformed about how to respond. New York and many other cities lacked the kind of contingency plans their West Coast peers developed long ago, including protections for outdoor workers and designated places where people can go to breathe clean air. (“Breathing center” could become another climate-related term we’d rather not know.)

Health care providers should have protocols in place for handling a smoke emergency, Kass said in an interview. Those should include reaching out to vulnerable patients with instructions for how to stay safe and deal with breathing problems. Businesses and governments should have plans for limiting the exposure of outdoor workers and homeless people. And N95 masks shouldn’t be so hard to find; Kass suggested sending every household a pack of masks every fire season with instructions on how and when to use them.

The easiest fix of all is for public officials to broadcast widely and often about the dangers of smoke and how to avoid it. It’s not rocket science: Shun the outside air, preferably by staying in a room with a HEPA filter; recirculate the air in your car; and wear some kind of mask, preferably an N95, when you must venture out.