Based on these timelines , it is estimated , in principal , that the NOX controls needed to comply with a multipollutant strategy can be met provided ( 1 ) an adequate supply of materials and labor is available , and ( 2 ) the control technology implementation process begins at least about 35 months prior to the date controls must be in place .
The supply of materials and labor is often in shortage , which makes it hard for the NOX controls to comply with that strategy .