BOULDER, Colo. (KDVR) — The Boulder Main Library was closed on Monday for environmental testing after methamphetamine residue was found in the air ducts of six bathrooms, according to a release.

It was not clear how long the closure of the library, located at 1001 Arapahoe Ave., would last, the city said.

Tests of the restroom air ducts were voluntarily done after a spike in reports of people smoking in public restrooms over the last four weeks, the city said.

The new testing will include swab samples inside and outside the bathrooms.

According to the city, there have been 12 to 15 incidents of people possibly doing meth in the bathroom that were reported to security.

On two separate occasions, city employees were evaluated and cleared for health concerns after experiencing symptoms of possible meth exposure, the city said. The employees were medically cleared by paramedics.

There was no indication that individuals who have been in the library and the bathrooms will face significant health risks, according to the city.

Additionally, the city said it has not received any complaints of patrons dealing with issues from meth exposure.

However, the city said anyone experiencing symptoms of low-level meth exposure should consult with their health care provider. The symptoms can include headache, nausea, dizziness and fatigue.