Like many holiday traditions, lighting candles and fireplaces is best done in moderation

The warm spices in gingerbread, the woodsy aroma of pine and fir trees, and the fruity tang of mulled wine are smells synonymous with the holiday season. Many people enjoy lighting candles, incense and fireplaces in their homes to evoke the moods associated with these festive fragrances.

Burning scented products may create a cozy ambiance, and in the case of fireplaces, provide light and heat, but some experts want people to consider how doing so contributes to the quality of the air indoors. All flames release chemicals that may cause allergy-like symptoms or contribute to long-term respiratory problems if they are inhaled in sufficient quantities.

However, people don't have to stop sitting by the hearth or get rid of products like perfumed candles and essential oil diffusers, said Dr. Meredith McCormack, director of the pulmonary and critical care medicine division at John Hopkins University’s medical school. Instead, she recommends taking precautions to control the pollutants in their homes.

“Clean air is fragrance free,” said McCormack, who has studied air quality and lung health for more than 20 years. “If having seasonal scents is part of your tradition or evokes feelings of nostalgia, maybe think about it in moderation.”

People in the Northern Hemisphere tend to spend more time indoors during the end-of-year holidays, when temperatures are colder. Indoor air can be significantly more polluted than outdoor air because pollutants get trapped inside and concentrated without proper ventilation or filtration, according to the American Lung Association.

For example, active fireplaces and gas appliances release tiny airborne particles that can get into the lungs and chemicals like nitrogen dioxide, a major component of smog, according to the U.S. Environmental Protection Agency. Cleaning products, air fresheners and candles also emit air pollutants at varying concentrations.

The risk fragrances and other air pollutants may pose to respiratory health depends on the source, the length and intensity of a person’s exposure, and individual health, McCormack said.

It is also important to note that some pollutants have no smell, so unscented products still can affect indoor air quality, experts say.

Polluted air affects everyone but not equally. Children, older adults, minority populations and people of low socioeconomic status are more likely to be affected by poor air quality because of either physiological vulnerabilities or higher exposure, according to the environmental agency.

Children are more susceptible to air pollution because of their lung size, which means they get a greater dose of exposure relative to their body size, McCormack said. Pollutants inside the home also post a greater hazard to people with heart or lung conditions, including asthma, she said.

Signs of respiratory irritation include coughing, shortness of breath, headaches, a runny nose and sneezing. Experts advise stopping use of pollutant-releasing products or immediately ventilating rooms if symptoms occur.

“The more risk factors you have, the more harmful air pollution or poor air quality indoors can be,” McCormack said.

Ellen Wilkowe burns candles with scents like vanilla and cinnamon when she does yoga, writes or when she is showering at her home in New Jersey. Her teenage daughter, on the other hand, likes more seasonally scented candles like gingerbread.

“The candle has a calming presence. They are also very symbolic and used in rituals and many religions,” she said.

Wilkowe said she leans toward candles made with soy-based waxes instead of petroleum-based paraffin. Experts note that all lit candles give off air pollutants regardless of what they are made of.

Buying products with fewer ingredients, opening windows if the temperatures allow, and using air purifiers with HEPA filters are ways to reduce exposure to any pollutants from indoor fireplaces, appliances and candle displays, McCormack said. She also recommends switching on kitchen exhaust fans before starting a gas-powered stovetop and using the back burners so the vent can more easily suck up pollutants.

Setting polite boundaries with guests who smoke cigarettes or other tobacco products is also a good idea, she said.

“Small improvements in air quality can have measurable health benefits," McCormack said. "Similarly to if we exercise and eat a little better, we can be healthier.”

Rachael Lewis-Abbott, a member of the Indoor Air Quality Association, an organization for professionals who identify and address air quality problems, said people don't usually notice what they are breathing in until problems like gas leaks or mold develop.

“It is out of sight, out of mind,” she said.

FILE - This Nov. 1, 2017 photos shows a scented candle produced by Bristol, Tenn., resident Jessie Duckett at her home business. (Andre Teague/Bristol Herald Courier via AP, File)

FILE - The vice president's official residence living room is decorated with a Christmas tree featuring whimsical old fashioned toys and a Christmas wreath above a fireplace Monday, Nov. 30, 2020 in Washington. (AP Photo/Manuel Balce Ceneta, File)

FILE- An scented candle called Bright Christmas Morning is shown at a Bath and Body Works store on Wednesday, Oct. 9, 2024, in New York. (AP Photo/Peter Morgan, File)

FILE - The vice president's official residence living room is decorated with a Christm (AP Photo/Manuel Balce Ceneta, File)

FILE - This Feb. 2, 2015 photo shows rocking chairs in front of the massive stone fireplace in the lobby of the Grove Park Inn in Asheville, N.C. (AP Photo/Beth J. Harpaz, File)

PROVIDENCE, R.I. (AP) — A person of interest was in custody Sunday after a shooting during final exams at Brown University that killed two students and wounded nine others, though key questions remained unanswered more than 24 hours after the attack.

The attack Saturday afternoon set off hours of chaos across the Ivy League campus and surrounding Providence neighborhoods as hundreds of officers searched for the shooter and urged students and staff to shelter in place. The lockdown, which stretched into the night, was lifted early Sunday, but authorities had not yet released information about a potential motive.

The person of interest is a 24-year-old man from Wisconsin, according to two people familiar with the matter. The people were not authorized to publicly discuss details of the investigation and spoke to The Associated Press on condition of anonymity.

Col. Oscar Perez, the Providence police chief, said Sunday afternoon that no one has been charged yet. Perez, who also said no one else was being sought, declined to say whether the detained person had any connection to Brown.

The person was taken into custody at a Hampton Inn hotel in Coventry, Rhode Island, about 20 miles (32 kilometers) from Providence, where police officers and FBI agents remained Sunday, blocking off a hallway with crime scene tape as they searched the area.

The shooting occurred during one of the busiest moments of the academic calendar, as final exams were underway. Brown canceled all remaining classes, exams, papers and projects for the semester and told students they could leave campus, underscoring the scale of the disruption and the gravity of the attack.

As police scoured the area for the shooter, many students remained barricaded in rooms while others hid behind furniture and bookshelves. One video showed students in a library shaking and wincing as they heard loud bangs just before police entered the room to clear the building.

University President Christina Paxson teared up while describing her conversations with students both on campus and in the hospital.

“They are amazing and they’re supporting each other,” she said at a news conference. “There’s just a lot of gratitude.”

The gunman opened fire inside a classroom in the engineering building, firing more than 40 rounds from a 9 mm handgun, a law enforcement official told AP. Two handguns were recovered when the person of interest was taken into custody and authorities also found two loaded 30-round magazines, the official said. One of the firearms was equipped with a laser sight that projects a dot to aid in targeting, said the official, who was not authorized to discuss the investigation publicly and spoke to AP on the condition of anonymity.

One student of the nine wounded students had been released from the hospital, said Paxson. Seven others were in critical but stable condition, and one was in critical condition.

Durham Academy, a private K-12 school in Durham, North Carolina, confirmed that a recent graduate, Kendall Turner, was critically wounded. The school said her parents were with her.

“Our school community is rallying around Kendall, her classmates, and her loved ones, and we will continue to offer our full support in the days ahead,” the school said.

On Sunday evening, city leaders, residents and others gathered at a park to honor the victims. The event originally was scheduled as a Christmas tree and Hanukkah menorah lighting.

“For those who know at least bit of the Hanukkah story, it is quite clear that if we can come together as a community to shine a little bit of light tonight, there’s nothing better that we can be doing,” Mayor Brett Smiley said at a news conference earlier in the day.

Smiley said he visited some wounded students and was inspired by their courage, hope and gratitude. One told him that active shooting drills done in high school proved helpful.

“The resilience that these survivors showed and shared with me, is frankly pretty overwhelming,” he said.

Investigators were not immediately sure how the shooter got inside the first-floor classroom at the Barus & Holley building, a seven-story complex that houses the School of Engineering and physics department. The building includes more than 100 laboratories, dozens of classrooms and offices, according to the university’s website.

Engineering design exams were underway. Outer doors of the building were unlocked but rooms being used for final exams required badge access, Smiley said.

Emma Ferraro, a chemical engineering student, was in the lobby working on a final project when she heard loud pops. Once she realized they were gunshots, she darted for the door and into a nearby building where she waited for hours.

Surveillance video released by police showed a suspect, dressed in black, walking from the scene.

Eva Erickson, a doctoral candidate who was the runner-up earlier this year on the CBS reality competition show “Survivor,” said she left her lab in the engineering building 15 minutes before shots rang out.

The engineering and thermal science student shared candid moments on “Survivor” as the show’s first openly autistic contestant. She was locked down in the campus gym following the shooting and shared on social media that the only other member of her lab who was present was safely evacuated.

Brown senior biochemistry student Alex Bruce was working on a final research project in his dorm across the street from the building when he heard sirens outside.

“I’m just in here shaking,” he said, watching through the window as officers surrounded his dorm.

Brown, the seventh-oldest higher education institution in the U.S., is one of the nation’s most prestigious colleges, with roughly 7,300 undergraduates and more than 3,000 graduate students.

Ramer reported from Concord, New Hampshire. Contributing were Associated Press journalists Jennifer McDermott in Providence; Christopher Weber in Los Angeles; and Alanna Durkin Richer, Mike Balsamo and Eric Tucker in Washington, D.C.

Passers-by walk past crime scene tape at an entrance to Brown University, Sunday, Dec. 14, 2025, in Providence, R.I., following the Saturday, Dec. 13, shooting at the university. (AP Photo/Steven Senne)

A bouquet of flowers rests on snow, Sunday, Dec. 14, 2025, on the campus of Brown University not far from where a shooting took place, in Providence, R.I. (AP Photo/Steven Senne)

A pedestrian walks across the intersection of Waterman St. and Hope St. Sunday, Dec. 14, 2025, after a shooting on Saturday in Providence, R.I. (Lily Speredelozzi/The Sun Chronicle via AP)

Pedestrians walk past and glance at the scene of a shooting at Brown University Sunday, Dec. 14, 2025, after a shooting on Saturday in Providence, R.I. (Lily Speredelozzi/The Sun Chronicle via AP)

Police caution tape lays askew at Brown University's Ittleson Quad Sunday, Dec. 14, 2025, after a shooting on Saturday in Providence, R.I. (Lily Speredelozzi/The Sun Chronicle via AP)

Police tape off hotel rooms where the person of interest was arrested in a shooting in Coventry, RI., (AP Photo/Kimberlee Kruesi)

Police tape off hotel rooms where the person of interest was arrested in a shooting in Coventry, RI., (AP Photo/Kimberlee Kruesi)

A police officer hangs yellow crime tape at Brown University in Providence, R.I., on Saturday, Dec. 13, 2025, during the investigation of a shooting. (AP Photo/Mark Stockwell)

Emergency personnel gather on Waterman Street at Brown University in Providence, R.I., on Saturday, Dec. 13, 2025, during the investigation of a shooting. (AP Photo/Mark Stockwell)

Police vehicles rest in intersections in a neighborhood near Brown University, Sunday, Dec. 14, 2025, in Providence, R.I., following a shooting at the university Saturday, Dec. 13. (AP Photo/Steven Senne)

A police vehicle rests at an intersection near crime scene tape at Brown University, Sunday, Dec. 14, 2025, in Providence, R.I., following a Saturday, Dec. 13, 2025 shooting at the university. (AP Photo/Steven Senne)

Mayor Brett Smiley speaks to reporters during a Brown University news conference, in Providence, R. I., Sunday, Dec. 14, 2025. (AP Photo/Kimberlee Kruesi)

Law enforcement officials carry rifles while walking on a street in a neighborhood near Brown University in Providence, R.I., on Saturday, Dec. 13, 2025 during the investigation of a shooting. (AP Photo/Steven Senne)

Brown University President Christina H. Paxson attends a news conference addressing the investigation following a shooting on Brown University's campus Saturday, Dec. 13, 2025, in Providence, R.I. (Lily Speredelozzi/The Sun Chronicle via AP)

Students are escorted by law enforcement officers to a building at Brown University after a shooting, Saturday, Dec. 13, 2025, in Providence, R.I.. (AP Photo/Charles Krupa)

Law enforcement officials carrying weapons gather near Brown University in Providence, R.I., on Saturday, Dec. 13, 2025, during the investigation of a shooting. (AP Photo/Steven Senne)

A law enforcement official walks past articles of clothing on a sidewalk near an entrance to Brown University, Saturday, Dec. 13, 2025, in Providence, R.I., during the investigation of a shooting. (AP Photo/Steven Senne)