The fifth North American Intercomparison of Ultraviolet Monitoring Spectroradiometers was held June 13 to 21, 2003 at Table Mountain outside of Boulder, Colorado, USA. The main purpose of the Intercomparison was to assess the ability of spectroradiometers to accurately measure solar ultraviolet irradiance, and to compare the results between instruments of different monitoring networks. This Intercomparison was coordinated by NOAA and included participants from six national and international agencies. The UV measuring instruments included scanning spectroradiometers, spectrographs, and multi-filter radiometers. Synchronized spectral scans of the solar irradiance were performed between June 16 and 20, 2003. The spectral responsivities were determined for each instrument using the participants' lamps and calibration procedures and with NOAA/CUCF standard lamps. This paper covers the scanning spectroradiometers and the one spectrograph. The solar irradiance measurements from the different instruments were deconvolved using a high resolution extraterrestrial solar irradiance and reconvolved with a 1-nm triangular band-pass to account for differences in the bandwidths of the instruments. The measured solar irradiance from the spectroradiometers using the rivmSHIC algorithm on a clear-sky day on DOY 172 at 17.0 UTC (SZA = 30o) had a relative 1- standard deviation of +/-2.6 to 3.4% for 300- to 360-nm using the participants' calibration.
Exposures to UVA radiation (320 − 400 nm) have been linked to increasing the risk of skin cancer, premature skin photoageing and skin wrinkling. The relative proportion of the UVA irradiances in the solar spectrum changes with time of day and season. Material such as window glass found in offices, homes and motor vehicles acts as a barrier to the shorter solar UVB wavelengths (280 - 320 nm) and transmits some of the longer UVA wavelengths (dependent on the type of glass). As a result, the spectrum of the filtered UV transmitted through the material may be substantially different from that of the unfiltered solar UV spectrum. This results in a change in the relative ratio of UVA to UVB irradiances and a consequent change in the biologically damaging UV exposures. For these environments where the UVB wavelengths have been removed and the UVA wavelengths are still present, it is necessary to consider the erythemal irradiances due to these UVA wavelengths only. This paper investigates the times taken for an exposure of 1 SED (standard erythemal dose) due to the UVA wavelengths.
This paper will overview the significant issues facing researchers in relating the impact of exposure to sunlight and human health. Exposure to solar ultraviolet radiation is the major causative factor in most sun-related skin and eye disorders, however, very little is known quantitatively about human UV exposures. Interestingly, human exposure to sunlight also has a nutritional impact, namely the development of pre-Vitamin D, which is an important nutrient in bone health. New research suggest that low vitamin D status may be a causative factor in the development of selective types of cancer and autoimminue diseases, as well as a contributing factor in bone health. The 'health duality' aspect of sunlight exposure is an interesting and controversial topic that is a research focus of Kimlin's research group.