In 2003, 22 states east of the Mississippi River must comply with new NOx emission requirements. These reductions were ordered because EPA has found that long-range transport of ozone and ozone precursors from upwind states negatively impacts air quality in the northeast. Each state must develop its own regulations based on federally-mandated targets. These state efforts are required because EPA called on the states to submit new State Implementation Plans (SIPs) to address ground level ozone. Large stationary sources are effectively required to reduce emissions by 85% from 1990 levels to a target emission rate of 0.15 lbs/MMBtu. However, several states currently disagree with EPA's required levels and are actively seeking relief from the new requirements. The ultimate fate of SIP Call requirements are undetermined at present.