Monitoring did, however, detect large quantities of volatile organic compounds not on emissions reports of any petrochemical factory within a wide radius of the test site. First, the reported inventory failed to account for the emissions we did detect. Second, large-scale emissions were reported but didn't show up in our observations. Henry suspects that similar experiments in other industrial areas would produce similar results. Even in areas with serious smog problems, few monitoring stations are currently at work.
Regulators depend almost exclusively on self-reporting by industry.
Henry believes that monitoring instruments should be more widely used in air-quality data gathering. However, the employee costs might be reduced by automation. In Southern California, a network of approximately 20 stationary monitoring sites could give regulators a far more accurate picture of the state of the air. A small number of mobile units could be deployed to provide more detailed information in special situations - when a large, unexplained burst of pollution was detected, for example. You check your work.