Smoke from wildfires in Canada that pushed deep into the United States this week has reached new areas in the South, including in North Carolina and Georgia, that had mostly escaped the toxic drift blowing in from the fires in June, officials said.

“Horrific up here!” Merry Miller Weis, a 70-year-old resident in the Western North Carolina mountains, wrote in an email to state climate scientists. “The mountains aren’t even visible. This is the absolute worst since the beginning of the Canadian fires.”

In June, heavy smoke from fires in the Canadian province of Quebec wafted toward the East Coast, enveloped parts of New York and moved through other states, past Washington, D.C., and as far west as Minnesota. This month, the vast plume has wafted in from fires in Canada’s Northwest, smothering the skies and raising warnings about the impact on health.

Corey Davis, the assistant state climatologist in North Carolina, said in an interview on Tuesday that his office had received the unsolicited email from Jackson County, a part of the state that was new territory for smoke attributed to the Canadian wildfires to linger. In June, it appeared mostly in the north-central urban region known as the Triad.

“It is now more concentrated in the West,” Mr. Davis said. “We have a high pressure system parked over the western part of the state. It’s like putting a lid on a pot of boiling water. Smoke mainly from the western Canadian wildfires is basically trapped right at the ground level.”

Around 8 a.m. on Tuesday, more than 44 million people in 28 states and Washington, D.C. continued to be affected by smoke from the fires, and many states in the South are under heat advisories, including parts of Georgia and Tennessee.

In Greensboro, a reading of the air quality index was in the range of 152 early on Tuesday, and in Atlanta, the index measured 150 by noon, both unhealthy levels.

Mr. Davis, describing the sky in Raleigh as a “pale orange, completely blank canvas,” said the state’s Western region “may be a little bit worse than what we had last month.” He said the state was at “Code Orange” — meaning an unhealthy air quality for sensitive groups — for four days last month, “the most in 11 years.”

In Georgia, smoke infiltrated the sky over more communities in Atlanta and along the border with Tennessee, and for the first time in Athens, said Jim Boylan, the chief of the air protection branch at Georgia’s Environmental Protection Division.

That data was based on readings of particulate matter from seven monitors: five around Atlanta, one in Rossville and one in Athens, he said. All were Code Orange on the air quality index, which means unhealthy for sensitive groups. In June, four monitors picked up those readings.

“This time we have more locations than last time,” he said.

Over the past few days, government officials have advised residents to curtail their outdoor activity and, in some cases, to wear a mask.

“I quickly ran an errand, and my eyes and throat feel as if they’re on fire,” Ms. Weis wrote in the email to Mr. Davis said. “And I had on a mask!”

Reached by telephone on Tuesday, she said that the smoke had settled below the tree line in the mountains where she lives in the region of Cullowhee, obscuring her view of the Blue Ridge Mountains and Mount Pisgah, about 40 miles away as the crow flies.

“Usually, it is a spectacular view,” she said. “But they have just disappeared.”