photo of the National September 11 Memorial and Museum monument

The National September 11 Memorial and Museum was evacuated Sunday afternoon for two hours due to a “hazardous materials situation” — which is fancy way of saying "a bad smell." 

According to a report by CBS News, the trouble began when patrons noticed a strong chlorine odor coming from the famous reflecting pool. 

“People were coughing. I had difficulty breathing,’’ a police officer reported to Firehouse, a resource for firefighters. As a result, the museum was vacated and the Department of Environmental Protection was called in to test the water. 

According to a maintenance worker, museum employees were adding too much chlorine to the water. Museum reps, however, say the smell was a result of decomposing algae, perhaps exacerbated by rain the night before. 

For more info, CBS turned to Dr. Michael Caldwell, the former Health Commissioner for New York's Dutchess County. 

"When it gets too much, especially on a hot day like today, [the chlorine] probably aerosolized, so there have been more coming off in the air," he said. "And with a bunch of people here on a Sunday, there are more people being affected."

Cailley Hammel is Managing Editor of AQUA Magazine.