Several environmental and community groups are suing the U.S. Environmental Protection Agency for failing to act on a permit challenge involving U.S. Steel Gary Works.

The groups claim the country’s largest steel mill is operating under a deficient air permit that lacks adequate pollution monitoring.

According to the lawsuit, the E-P-A has missed a mandatory sixty-day deadline to address the petition.

Advocates say real-time tracking is desperately needed to protect public health in Northwest Indiana and the Chicago area.