There is a growing health crisis in Puerto Rico as more residents develop asthma following Hurricane Maria.

On September 20, Hurricane Maria made landfall on the island, causing a total blackout, catastrophic flooding and more than 4,000 deaths. The storm’s impact on the island’s air quality has created conditions that exacerbate asthma. Per The Associated Press:

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’s asthma rates were high prior to the storm. An estimated 10.2 percent of people on the island had asthma before Maria, per the most recent (2015) figures from the U.S. Centers for Disease Control (CDC). That’s compared to the 8.3 percent of U.S. adults living on the mainland and in territories who were diagnosed with asthma at some point in their lives, per a 2016 CDC report.

Generators, which many still depend on for electricity, can exacerbate the problem as the diesel or gasoline that powers them releases toxins into the air. Since the hurricane, generators are used daily in hospitals, schools and water treatment plants, as repairs to the power grid continue. In addition, The Federal Emergency Management Administration (FEMA) has more than 1,200 generators in Puerto Rico. The AP reports that many older models don’t meet current pollution standards, though FEMA claims that all of its generators do. Per The AP:

Vieques and Culebra, just east of Puerto Rico, are still completely dependent on generators. Dr. Juan Manuel Roman travels to Culebra weekly and said that in addition to new patients, his regular patients are seeking treatment far more often. Roman said it’s hard to escape the fumes from all the generators that keep the tiny island energized.

There are many other factors contributing to the rise in asthma. These include an increase in mold spores; the island recorded its highest levels in a decade this past May. Structures without an intact roof because of storm damage are more susceptible to mold, as moisture comes inside. Rats, mice and cockroaches—which are reportedly causing problems in homes—can also trigger asthma attacks.

Says Benjamin Bolanos, director of the San Juan Aeroallergens Station of the American Academy of Allergy, Asthma and Immunology, to The AP, “We have never seen something like this.”