SAN JUAN, Puerto Rico — Shortly after he turned 2, Yadriel Hernandez started struggling to breathe. His doctor prescribed an inhaler and an allergy pill for asthma, and his symptoms were mostly under control.

Then Hurricane Maria devastated Puerto Rico, strewing mold-producing wreckage across the island and forcing many to use fume-spewing generators for power. The boy, now 8, started having twice-monthly attacks and needing nearly four times the amount of medicine he used to take.

His mother said weekly power outages in their coastal town of Aguadilla also feed his anxiety, which can make symptoms worse. He panics about not being able to turn on the plug-in nebulizer that helps control his attacks.

“The lights go out and he breaks down,” said Johana Hernandez. “He cries out, ‘The power is gone, mom! The power is gone! I’m going to have an asthma attack!’”

Doctors in Puerto Rico say they are seeing an alarming rise in the number and severity of asthma cases that they attribute to destruction caused by the deadly hurricane that walloped the island in September. The chronic lung disease is caused by such things as pollution, airborne mold and pollen, all of which have increased post-Maria.

“It has increased so, so, so much after the hurricane,” said Dr. Ivette Bonet, who treats low-income patients at a clinic in the working-class neighborhood of Santurce. Bonet says she has dozens of new patients who never had asthma before the Category 4 storm hit.

“Now they have this cough that they can never get rid of,” she said.

Puerto Rico had high rates of asthma even before the hurricane. An estimated 435,000 people on the island of 3.3 million, or 13 percent, had asthma before Maria pummeled the territory on Sept. 20, according to Puerto Rico’s Health Department. That compares to 8.3 percent who suffered from asthma on the U.S. mainland in 2016, according to the latest available figures from the U.S. Centers for Disease Control.