Emmy Award-winning journalist Kris Van Cleave is the senior transportation correspondent for CBS News based in Phoenix, Arizona, where he also serves as a national correspondent reporting for all CBS News broadcasts and platforms.

Back in February, the cabin of Delta flight 876 filled with hazy smoke mid-flight, forcing the plane to make an emergency landing.

Similar smoke or fume events happen on airliners at a rate of more than three a day, according to a CBS News review of Federal Aviation Administration incident reports. Experts say those fumes can be toxic.

Dr. Robert Harrison, an occupational medicine specialist at the University of California San Francisco who has treated more than 100 flight crew members for toxic exposure, told CBS News, "The most common problems I see are general nervous system problems."

"A person breathes [the fumes] into their lungs, it circulates around, and then it gets into their brain and can affect the other parts of the nervous system," he explained.

It's an issue flight attendants have been raising alarms about for years. Vanessa Woods told CBS News back in 2016 that she passed out after a chemical odor filled the cabin on a flight she was working on.

"I felt like I might die, and I thought, you know, I wonder what my mom is going to think, this, I went to work, and you know, I may not make it," she said at the time.

A Wall Street Journal investigation published over the weekend found the fume issue was most common on the popular Airbus A320 family of narrowbody jets.

The CBS News Data Team found Airbus accounted for about 61% of reported fume incidents last year -- nearly three times more than Boeing aircraft.

Airbus told CBS News in a statement that its aircraft "are designed and manufactured according to all relevant and applicable airworthiness requirements."

"We are committed to continuously enhancing our products, working closely with operators and regulators to ensure the best possible cabin environment for passengers and crew," Airbus said.

Delta Air Lines told CBS News its "safety management system and safety culture help us address root causes of potential issues to reinforce that air transportation remains the safest form of travel in the world."

Delta also told CBS News that it's in the process of replacing auxiliary power units on its A320s. As of Monday, that work was about 80% complete, a spokesperson said.

"Every aircraft should really have the filtration system on it to avoid those toxins from getting into the circulated air in the cabin," said Sara Nelson, president of the Association of Flight Attendants-CWA.

Nearly all commercial jets "bleed" fresh air in from the plane's engines. It's then fed through an air conditioner and into the cabin. But if an engine seal fails, oil and other potentially toxic particles can be released. According to incident reports filed by airline employees, fumes are often compared to the smell of dirty socks.

The FAA told CBS News it has "strict cabin air standards, and studies have shown cabin air is as good as or better than the air found in offices and homes."

"In rare instances, mechanical issues such as failures of an engine oil seal or recirculation fan bearings can cause fumes to enter the cabin. Airlines are required to report these incidents to the FAA," the agency said. "The FAA investigates the causes and makes sure they're fixed before the aircraft returns to service."

Boeing said in a statement, "Independent researchers, universities, industry groups, and government agencies have conducted extensive research on cabin air quality. The results repeatedly demonstrate that contaminant levels on aircraft are generally low and that health and safety standards are met. Based on that research, the world's five leading aerospace medical associations have rejected a connection between cabin air and significant health effects, and no aviation regulator has determined that additional safety regulations are required. Boeing continues to work with scientists to improve our understanding of cabin environmental factors and to study potential new technologies."

Fume incidents on airplanes raise health concerns for passengers, crew members