"A coalition of 17 states and New York City are suing the Environmental Protection Agency (EPA) over its decision not to tighten major air pollution standards.
The petition for review of the decision to retain current standards for fine particulate matter didn’t detail the states’ legal arguments.
However, a press release from California Attorney General Xavier Becerra’s (D) office said that they are arguing that the EPA “conducted a flawed and unlawfully biased review” and that “the available science clearly demonstrates the need for the EPA to strengthen the [standard].”"
Source: The Hill, 01/14/2021