At the same time, cleaning the environment also has opportunity costs, and this is particularly true of NOx. These include the costs of implementing the technologies to prevent or remove the NOx which require foregoing useful production elsewhere in the economy. Because meeting the federal ozone standards requires such substantial reductions in NOx, a host of regulatory strategies must be employed. This plan includes nearly 40 separate regulatory provisions. To understand both past and proposed pollution abatement strategies, the regional chemical processes which produce ozone need to be understood.
Many different pathways exist by which NOx emissions lead to the formation of ground level ozone.
While the reactions that take place are extremely complicated, some common elements may be noted. Also needed is sunlight, which provides energy for the reaction, and water, in the form of humidity. Relatively still air, which is often caused by temperature inversions of the air during time of high heat, allows the reactants to stay together rather than dispersing into the atmosphere. This last phenomenon causes the ozone season to be concentrated during the summer months, which in Houston last from May through September. This process is illustrated in Figure 2.1.