Smoke emanating from scores of raging Canadian wildfires has cloaked a vast stretch of the Northeast and Upper Midwest in a thick, suffocating haze. Parks closed, skylines vanished and officials urged residents to avoid spending much time in the polluted air.

The air quality readings were so dangerous in major cities like Chicago, Detroit, Milwaukee and Cleveland that one public health expert recommended that “nobody should spend time outside.” One Chicago man told us he could “feel it in my eyes” when he walked outside. “It has a metallic taste and probably isn’t too good of an idea to be out here long,” he added.

Readings in Philadelphia, Pittsburgh and the New York City area were also at unhealthy levels. (See the air quality near you, and consider a mask if the reading tops 200.)

In the Northeast, the smoke, which is now being trapped in by the same heat dome that has led to brutally high temperatures, should start to ease by tomorrow. In Ontario, where more than 100 wildfires were burning, 15 rural communities have been evacuated.

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In other weather news: Torrential rains have submerged much of Central Texas in floodwaters, killing at least one person, forcing scores of people to evacuate their homes — some by helicopter — and leaving a trail of damage.

Trump is set to deliver a prime-time speech on election security

President Trump has recently ratcheted up his unsubstantiated claims of widespread manipulation and rigging of U.S. elections. He is expected to return to the topic tonight in a 9 p.m. Eastern time address to the nation. Follow our live coverage here.

No evidence has emerged showing that vote counts have been corrupted. But Trump’s false claims have sometimes obscured genuine security concerns, particularly as they relate to foreign meddling. Here’s what to know.

In other Trump administration news:

Thousands of Ukrainians protest a military ouster

Mykhailo Fedorov — the young face of Ukraine’s successful drone warfare program who was forced out yesterday as defense minister — publicly denounced the country’s top general today. “Instead of figuring out how to defeat Russia asymmetrically,” Fedorov said about Oleksandr Syrskyi, the commander in chief, he “figured out how to split the country.”

Angry Ukrainians swarmed streets across the country to demand a reversal of Fedorov’s dismissal just six months into his tenure. Some saw the move as a victory for the old guard just as the war was starting to turn in Ukraine’s favor.

Fedorov, 35, angered well-connected defense contractors with programs threatening their businesses, such as one that allowed soldiers to buy their own weapons on a military website.

The F.D.A. approves a more powerful pill for cholesterol

The F.D.A. authorized a new daily pill today that can lower cholesterol levels far below what can be achieved with cheap, popular statins. The drug, which goes by the brand name Lipfendra, has been shown in clinical trials to lower levels of LDL, the dangerous type of cholesterol, to 50 or 60 — approximately the levels now recommended for those at high risk of heart attacks.

The pill’s list price will be $315 for a 30-day supply, cheaper than the currently available injectable drugs that work in the same way.

More top news

THE EVENING QUIZ

This question comes from a recent edition of the newsletter. Click an answer to see if you’re right.

Scientists recently found which key building block of life in interstellar space?

A Great American Novel turns 75

On this day in 1951, J.D. Salinger’s “Catcher in the Rye” was published with little fanfare. It wasn’t long before the book became a hit among teenagers, teachers and book critics, who were taken by Holden Caulfield’s voice of exasperation.

Three-quarters of a century later, the book — which has sold some 80 million copies — and its author have their detractors. But its influence has survived, despite (or perhaps because of) Salinger’s famous self-exile. “Catcher” might be the purest of the Great American Novels, our book critic Alexandra Jacobs writes, perhaps because it has never been made into a movie.

Is grunge … back?

Dexter and the Moonrocks’ “Freakin’ Out” seems to have come out of nowhere. It’s a grunge song that sounds more like the raw, rough rock of the 1990s than a modern pop track. But over the last few months it has quietly climbed the charts and racked up millions of streams. Our music critic Jon Caramanica breaks down why it works in the video above.

A chess master takes on 50 opponents to honor an artist

Susan Polgar, one of the greatest female chess players ever, is planning to play against 50 members of the art world on 50 different chess boards, all at the same time. The challenge is part of a MoMA exhibition honoring Marcel Duchamp, a pioneer of conceptual art who, like Polgar, saw chess as a kind of art form.

Duchamp may be most famous for challenging the very notion of art with sculptures made out of a urinal or a snow shovel. But midway through his life, Duchamp announced that he was abandoning art. He said that he preferred to spend his time playing chess.

Have a masterful evening.

Thanks for reading. I’ll be back tomorrow — Matthew

Eli Cohen was our photo editor.

We welcome your feedback. Reach us at evening@nytimes.com.