White House confirms Biden, 80, is now using breathing machine to treat sleep disorder - after thick mask lines on his face sparked more health questions

• President Joe Biden has started using a CPAP machine
• The machine treats sleep apnea  
• Biden's sleep apnea has been public knowledge since 2008

The White House said Wednesday that President Joe Biden, 80, has started using a CPAP machine to treat his sleep apnea - after he was spotted with visible indentations on his face. 

The mask lines were apparent as the president spoke with reporters on the South Lawn Wednesday morning before a day trip to Chicago. 

The West Wing quickly shut down conspiracy theories by confirming the lines were caused by the device that helps sufferers breath when they sleep. 

'Since 2008, the president has disclosed his history with sleep apnea in thorough medical reports. He used a CPAP machine last night, which is common for people with that history,' White House spokesperson Andrew Bates told DailyMail.com.

At 80, Biden is the nation's oldest president - and thus the White House is continually questioned about his health, especially as he's started to run for a second term in earnest. 

Other 2024 candidates have used it as a talking point - most notably former U.N. Amb. Nikki Haley, who said all hopefuls older than 75 should submit to a mental competency test.

Biden's sleep apnea has been public knowledge since October 2008, when the Obama campaign put out the vice presidential candidate's medical records ahead of the 2008 presidential election. 

At the time, doctors believed that Biden's irregular heartbeat, known as an atrial  fibrillation, was likely linked to his sleep apnea.

In subsequent health reports, the sleep apnea became a footnote. 

In a December 2019 medical report, released publicly while Biden was running for president, his now White House Physician, Dr. Kevin O'Connor said that Obstructive Sleep Apnea had been considered, but Biden's condition had improved after he had sinus and nasal passage surgeries. 

The president started using the CPAP in recent weeks. 

A CPAP machine blows air into the back of the throat to relieve a condition called obstructive sleep apnea, where muscles in the throat relax and block the airways.

This briefly stops sufferers from being able to breathe and wakes them up. 

They may also snore extremely loudly. 

Over time, the repeated interruptions to oxygen supply and disruption to sleep can have life-threatening consequences, pushing up levels of stress hormones in the body.

Untreated sleep apnea is closely linked with serious health problems, including diabetes, stroke and heart disease.

People over age 60 with sleep apnea also have a higher incidence of sudden cardiac arrest. 

Bloomberg first confirmed Biden was using the device. 

A source told the wire service that while Biden's use of the machine is a new development it wasn't prompted by a new medical condition or environmental conditions. 

Biden was flying to Chicago amid an air quality alert - due to Canadian wildfires. 

As the president left Washington, D.C., Wednesday morning, the capital was also under an air quality alert until mid-day Thursday.