Wind and rain arrived in Northern California this week, providing welcome relief to a region buffeted by the state's deadliest wildfire and then besieged for nearly two weeks by a dome of thick, noxious smoke.

A high-pressure system had stalled over the Sacramento Valley and the San Francisco Bay Area, leaving residents up to 200 miles south of the Camp Fire coughing, wheezing and tearing up from the acrid fumes.

The ashy cloud closed schools throughout the region for more than a week and forced the delay of the UC Berkeley-Stanford football game, postponed for the first time in more than half a century. Smoke from the fire that destroyed much of Paradise, California, blew all the way to the Atlantic coast.

"You see it everywhere and you feel something in your chest, a heaviness that is slightly painful," said Irva Hertz-Picciotto, a University of California, Davis researcher who is living with, and studying, the health impacts of the smoke. "It's just days and days and it doesn't go away. I felt like, 'I can't stand this.'"

Forecasters expected 25 mph winds and rain to blow away the worst of the fallout by Friday. While that would improve air quality, the wet weather raised fears of flooding and mudslides.

And the cleaner air does not mean that the health risks are over. Doctors as far away as Berkeley said that they continued to see a slight uptick this week in emergency room visits, particularly from asthmatics, the elderly and children — groups most vulnerable to polluted air.

Respiratory, heart and other complaints may also continue to crop up two or three weeks after the fire has been tamed — a delayed response that is probably due to the cumulative impact of breathing in tainted air for multiple days. That's what happened after last year's deadly fires in California's wine country, doctors said.

Longer-term impacts of such exposure, meanwhile, are little understood. Few studies have been conducted to track the health of people months, and years, after they have been exposed to high concentrations of “particulate” pollution. The emissions are similar to the toxic particles released with the burning of fossil fuels. But fire fumes could pose an additional risk, because they include chemicals released when homes and cars — and their attendant insulation, plastics and metals — burn.

From Butte County to Silicon Valley, doctors in some emergency rooms have reported slight increases in patients complaining of sore throats, eye irritation, coughing and difficulty breathing.

The increases were not obvious near the start of the Camp Fire Nov. 8, but set in as the fire persisted and an “inversion layer” settled over much of Northern California. That is a weather pattern in which high pressure keeps a virtual dome over an area. Inversions usually trap fog in California's valleys, but they also capture smoke after big fires.

For much of the last two weeks, the atmospheric stagnation has made residents from the Sacramento Valley to the Bay Area feel like they were trapped inside a giant brown balloon.

The Bay Area Air Quality Management District recorded 13 consecutive days of particulate pollution above 151 micrograms per cubic meter as of Tuesday. That's the level considered unhealthy for humans. It's the longest run of consecutive unhealthy air days, during winter, in the 63-year history of the air district, which covers nine counties.

Many patients coming to emergency rooms in the area did not connect the smoke to their symptoms, doctors said. They simply reported discomfort.

“You begin to realize that, if you have 50 people in the emergency room, as many as 25 percent of them have complaints like cough, sore throat and heart palpitations,” said Ronn Berrol, the medical director of the emergency department at Alta Bates Summit Medical Center in Berkeley. “You begin to think there must be a relationship to what is going on in the environment and people being exposed to air quality like this for seven, eight, nine, 10 days.”

It is too soon to have compiled data about the apparent increase in respiratory and related maladies, according to officials at Sutter Health, the biggest hospital chain in Northern California, and operator of the Berkeley hospital.

Berrol said he expects to continue seeing patients with respiratory complaints even after the smoke is gone.

“We are getting experience with these super fires over the last few years,” Berrol said, “and what we tend to see is that the inflammatory process of smoke exposure doesn’t stop as soon as the smoke goes away…The volume of these kinds of conditions will increase over the next week or two.”

Researchers at the University of California, Davis, began last year to recognize how little was known about longer-term impacts of smoke from wildfires. So they launched studies into the impacts of the 2017 Tubbs Fire in Sonoma County and other giant wine country blazes that killed more than 40 people.

Hertz-Piccioto, an environmental epidemiologist at UC Davis, has collected information from about 6,000 people from 2,000 households. She is looking beyond breathing problems to other symptoms, including depression, and behavioral changes like the use of alcohol and cigarettes.

"The conventional wisdom is that short-term exposure to smoke won't have a long-term impact on health," said Hertz-Picciotto. "But what is short? And what if it's two weeks of exposure, but recurring on a yearly basis? We are wondering at what point, and in what group of people, is there going to be an impact?"

Scientists are also trying to better understand exactly what is in the smoke that comes from fires in the so-called "wildland-urban interface." When cars and homes burn, along with trees, it means the release of chemicals that went into paint, plastics, insulation and metal.

A sampling of ash from last year's fires north of San Francisco Bay found 1,947 more chemical compounds in burned suburban neighborhoods than in areas of just trees and brush. No one yet knows what happens when people breathe in those compounds.

Another open question is the effectiveness of masks in preventing smoke-related illnesses, said Rebecca Schmidt, a UC Davis public health professor. Public health officials in Northern California prefer that people remain indoors during the worst smoke alerts but disagree on whether to recommend the masks.

“They just don’t know the answers,” Schmidt said. “When we looked at the information, there weren’t a lot of answers. And that is one of the reasons we decided to go forward.”

Schmidt researches the health impacts of fire smoke on pregnant women and their babies, both before and after they are born. She has taken samples from hair, placentas, saliva and umbilical cord blood and also surveyed about 200 women exposed to smoke from 2017's wine country fires. The results may be significant not only to mothers in future fire disasters but to the general population, Schmidt said.

Schmidt hopes to get approval to extend the study to include women breathing smoke from the Camp Fire. She's aiming to have preliminary results by early next year.

“We are learning these fires might be our new normal,” Schmidt said, “and it’s about time we start understanding them.”