CIESIN logo SEDAC logo NASA logo home page icon
Stratospheric Ozone and Human Health Project

Action Spectra

What is an action spectrum?

action spectra plot Three of the four action spectra displayed here show a rapid decline in relative response as the wavelength increases; this indicates that the UV-B portion of the spectrum is much more effective at eliciting a response than the UV-A wavelengths (note the logarithmic scale). These biological responses would then theoretically be more sensitive to ozone depletion since irradiance levels in the UV-B region increase with lower ozone levels. Conversely, the melanoma action spectrum for platyfish-swordtail hybrids shows a significant UV-A dependence, which indicates that ozone depletion would not have as great an impact on melanoma induction in this species of fish as would the responses described by the other action spectra.
Note, however, that a direct comparison of dose amounts for any induced effect cannot be made on the basis of action spectrum alone; these spectra only give an indication as to the relative effectiveness of particular wavelengths, not the actual dose amount required to produce a biological response.


de Gruijl, F.R. and J.C. van der Leun. 1994. Estimate of the wavelength dependency of ultraviolet cacinogenesis in humans and its relevance to the risk assessment of stratospheric ozone depletion. Health Physics, 67: 319-325.

McKinlay, A.F. and B.L. Diffey. 1987. A reference action spectrum for ultra-violet induced erythema in human skin. In Human Exposure to Ultraviolet Radiation: Risks and Regulations. W.F. Passchier and B.F.M. Bosnjakovich, eds. International Congress Series. pp. 83-87.

Setlow, R.B. 1974. The wavelengths in sunlight effective in producing cancer: a theoretical analysis. Proceedings of the National Academy of Sciences U.S.A., 71: 3363-3366.

Setlow, R.B., E. Grist, K. Thompson, and A.D. Woodhead. 1993. Wavelengths effective in induction of malignant melanoma. Proceedings of the National Academy of Sciences U.S.A., 90: 6666-6670.

UV data