NEW YORK (CBSNewYork) — The MTA Board voted on Wednesday, to test 20,000 employees for sleep apnea.

Outgoing MTA boss Tom Prendergast said all railroad engineers, subway conductors, and bus and subway operators will be tested.

The MTA board voted to sign contracts with four companies to do the testing, 1010 WINS’ Carol D’Auria reported.

He said it’s the right thing to do for the safety of all passengers and for the health of MTA workers.

He himself has been diagnosed with sleep apnea.

“And I didn’t know I had sleep apnea until I fell asleep driving a car three times, which is pretty serious. Thank god I wasn’t flying a plane,” he said.

People with sleep apnea are excessively tired because they have interrupted sleep.

Sleep apnea was determined to be the cause of a 2013 crash of a Metro North train in which 4 people were killed.