In a gutted basement on Beach 59th St. in the Rockaways, ominous, black splotches cover gypsum board, plaster walls and wooden support beams. Breathing itself is difficult.

Upstairs tenant Alberto Lespier, 56, says the ghastly rooms were supposedly “cleaned” by untrained workers who left behind toxic conditions he fears are ruining his health.

“I have high blood pressure,” he said, as he trudged through the contaminated space clutching a paper mask to his face. “This is no good.” 

In homes like this across Brooklyn and Queens, it’s increasingly clear that mold left behind by Hurricane Sandy continues to lurk behind walls, under floors and behind ceiling tiles, serving as a breeding ground for potentially deadly spores.

Sometimes, the “cleanups” are done by well-meaning volunteers, other times by contractors out to make a quick buck. In any event, hundreds of homeowners — particularly those who can’t afford to get the job done right — are now vulnerable, experts and officials say.

“This is a very widespread problem we’re talking about,” said William Sothern, chief investigator of Microecologies Inc. “In so many homes, the gutting has been done but little else has been done. We know a lot of people are closing up (walls) without treating the visible mold. It’s problematic.”

Recently, the Daily News accompanied Sothern and colleague Chris Mikrut to check out the Beach 59th St. home and several other mold-tainted homes — and quickly discovered the problem is not always obvious.

Moisture — mold’s best friend — can remain within wood for months. Mikrut placed a moisture-reading meter against what appeared to be a dry beam at Beach 59th St. and declared, “It’s still wet.”

In the next room, Sothern pointed to a plaster wall the untrained workers had left behind. A wisp of mold had already worked its way from floor to ceiling. “It’s growing on the paint,” he said.

Over on Beach 60th St. owner Nicole Harper, 46, faced a similar blight. After she emptied her flooded basement, a group of volunteers helped her tear out soaked wallboard, and a local handyman helped scrub surfaces of the studs underneath with Clorox and water.

But when Sothern and Mikrut checked out the porous studs on the 87-year-old house, they found mold everywhere.

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