needs. (Biomass production at sea could avoid this problem.) For most solar technologies, the main risks are those associated with extracting and processing the requisite large amounts of construction materials.
The difficult tasks of setting standards for ambient air quality and emissions have been greatly complicated by a lack of precise knowledge of the levels at which epidemiological effects first appear and of the diversity of such effects. Pragmatic decisions must therefore be made in the face of uncertainty—uncertainty magnified by the periodic (and appropriate) review of these standards. Industrialists may claim that the standards are set too low, in order to make them safe regardless of cost and convenience; this inhibits industrial planning and has been a deterrent in the further use of coal. The situation calls for a major research effort into the effects of pollutants, including emissions from mobile sources (nitrogen oxides, ozone, nonmethane hydrocarbons), as well as from the stationary sources (nitrogen oxides, sulfur oxides, particulates) that this chapter considers at length.
The committee recommends that investigation center on the dose-effect curve (or exposure-effect curve) in the region near and below the present ambient air quality standards.
The quantitative assessment of exposure, and if possible, of dose per individual, is essential to advance knowledge in this field. One or two centrally located stations are insufficient to monitor an urban area for epidemiological research (they may be sufficient for other purposes). Measurements of indoor and outdoor, residential and occupational exposures are necessary.
Mortality is too gross an endpoint to be used alone. Others must be selected for specific types of morbidity and for physiological and biochemical response.
While immediate responses are important, late effects in specific individuals may be even more important.
The effects of emissions on plants and ecosystems should receive major attention.
The magnitude of the several problems to be investigated necessitates undertaking and maintaining long-term studies. Some will take decades to complete.
Much of the work cannot be planned from first to last detail, and none of it should be subject to political control. Coupled with the need for an effort adequate in scale to the problems under investigation, there is a