Lukas Flippo, Staff Photographer

When Savannah Neibart ’26 entered her probability class on the morning of Sept. 6, she had not calculated the odds of a lecture-hall evacuation. 

Yet, at approximately 9:55 a.m., 15 minutes before the lecture’s set end time, students in “Probability Theory” began to cover their noses — some even getting up from their seats to leave the room — as smells of gas filled Marsh Lecture Hall in the Yale Science Building. 

“Someone raised their hand and said, ‘it smells like something is burning,’” Neibart told the News. “Then, people started running out of the classroom, and class ended abruptly.” 

The smell, which would later be attributed to gasoline-powered lawn equipment, comes just eleven months after students in certain Old Campus halls evacuated their rooms due to dangerous gas leakage.

While hundreds of students had to evacuate Phelps, Lawrance and Welch halls last October, John Liu ’25 — another student in the class — noted that only around 80 students were in the lecture hall during yesterday’s incident.

While students frantically packed up their bags and evacuated the building due to concern that the smell was the result of a gas leak, the Yale Fire Marshal’s Office later told the News that there was no leak in the building and classes could safely resume there.

Robert Doyle, manager of fire code compliance at the Fire Marshal’s Office, said his office responded to an odor complaint, which ultimately ended up stemming from a landscape contractor – Mike’s Landscape – using gasoline-powered lawn equipment in the “immediate vicinity” of the building’s fresh air intake system. 

“We spoke to the gentlemen doing the work and directed them to stop their work, explaining what had occurred,” Doyle wrote. “They complied with courtesy and without question.” 

While the lecture hall and its inhabitants were never in danger, a lack of communication remains puzzling to those involved in the incident. Classes in Marsh continued the rest of the day, and Neibart — who had “Introductory Microeconomics” in the same room at 1 p.m. — was concerned and confused about returning to the space she had earlier been instructed to evacuate. 

Conrad Lee ’25 noted that the lack of communication around the incident, especially with such an abrupt end to class, felt “strange.”

Those who reported the incident, including “Probability Theory” professor Yihong Wu, received no follow-up after the initial report. Wu expressed to the News feeling “curious” about the incident and still having no clarity on the situation as of 3 p.m. the same day. 

Students enrolled in the class and in other classes located in Marsh Lecture Hall have still not been sent communication on the situation or its resolution.

The Yale Science Building, which houses March Lecture Hall, is located at 260 Whitney Ave.