NEW YORK (AP) — Former New York City Mayor Rudy Giuliani is breathing on his own after being hospitalized with pneumonia and placed on a ventilator, his spokesperson said Monday.

Giuliani, 81, remains in critical but stable condition at a Florida hospital and is being monitored as a precautionary measure, spokesperson Ted Goodman said.

Goodman said Giuliani’s condition was exacerbated by restrictive airway disease attributed to his exposure to dust and toxins from the Sept. 11, 2001, attack on the World Trade Center.

Giuliani’s hospitalization, near Palm Beach, Florida, came after he was heard coughing Friday on his nightly online talk show and hoarsely told viewers that his voice was “a little under the weather.”

“This condition adds complications to any respiratory illness, and the virus quickly overwhelmed his body, requiring mechanical ventilation to maintain adequate oxygen and stabilize his condition,” Goodman said in a statement.