“You can see the ocean; it’s nice,” said Cruz, a Lynn resident. “But we’re not looking around much.”

They had to pay attention to their work, because the two employees of Waltham-based demolition company NASDI , LLC were roughly 75 feet in the air on a lift platform.

They were taking down a 1930s smokestack at Anna Jaques Hospital, one of the last projects funded by a $6.5 million capital campaign.

After the chimney and the old boiler plant at its base are demolished and the debris hauled away, the hospital will build a new entrance plaza on the site. That follows the recent construction of a more efficient power plant and a new, 18-bed inpatient unit. (There will not be a net increase in beds at the 123-bed hospital, but more private rooms.)

Cruz, Sirois, and several coworkers on the ground were charged with demolishing the smokestack, along with the boiler and other facilities at its base. They worked with a pneumatic rivet buster and a heavy, ax-like adze to knock a few bricks at a time off the stack, most falling inside.

The trickiest part was at the beginning, demolishing the top of the chimney where it widened out in a sort of cone or nozzle.

“You’ve got to get it to drop inside,” Cruz said. “I don’t want it to drop on me or the top of the building [below].”

When they got it down to about 30 feet of chimney, they would use another vehicle with a hydraulic arm to pull it down.