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Biomedical subjects

M Blumthaler

Publications and source records attributed to M Blumthaler.

At least 19 recordsLinked to original sources
PubMed2006

Diurnal discrepancies in spectral solar UV radiation measurements.

Unexpected diurnal discrepancies between high-quality spectroradiometers were observed during the 2000 Nordic Ozone Group Intercomparison campaign. The spectral ratios of the irradiances showed a diurnal variation of approximately 2-9%. This cannot be explained by the nonideal angular response of the instruments' input optics in one plane (cosine effect). Instead, by using a radiative transfer model, we show that differences in the angular response in four azimuth planes have the potential to bias the measured data by up to 4.4% (azimuth effect). Other relevant factors are also discussed and quantified and are shown to be significant when diurnal changes in radiation are explained by environmental factors, or when measured data are compared with model or satellite data. Again, intercomparison campaigns have the potential to reveal errors that would otherwise remain undetected.

Journal Article↗
PubMed1999

Spectral UV irradiance on vertical surfaces: a case study.

The UV spectral irradiance on horizontal and vertically oriented surfaces was measured throughout a cloudless day (18 July 1995) at Izana station, Tenerife, using a Bentham DTM300 spectroradiometer scanning from 290 to 500 nm in steps of 5 nm. Results show that irradiance measured on a horizontal surface is not proportional to irradiance on a vertical surface. The relation between the two depends upon orientation of the vertical surface, zenith angle and wavelength. At short UVB wavelengths surfaces directed toward the solar azimuth received their maximum irradiances much closer to solar noon than the maxima for longer wavelengths. Some vertical surfaces also received significantly more irradiance than the horizontal surface at long wavelengths during all but the central hours of the day, while at short wavelengths all vertical irradiances were less than the horizontal except for the measurements at the extreme ends of the day. Erythemally effective radiation followed the diurnal pattern of irradiations for short UVB wavelengths.

Humans↗
PubMed1998

Effectiveness of eye drops protective against ultraviolet radiation.

BACKGROUND: To test the effectiveness of commercially available ultraviolet (UV)-protective eye drops (8-hydroxy-1-methylchinolinium methylsulphate) which are recommended for protection against both solar and artificial UV radiation. METHODS: The spectral transmission in the wavelength range from 250 to 500 nm was investigated in 1-nm steps using a high-resolution double monochromator with holographic gratings of 2,400 lines/mm and a 1,000-watt halogen lamp as light source. The transmission spectrum was measured for different values of the layer thickness. RESULTS: The transmission of a liquid layer of about 10 microns, which corresponds to the thickness of the human tear film, shows a cut-off at 290 nm with a transmission of about 25-50% at shorter wavelengths. For wavelengths longer than 290 nm the transmission is higher than 90%. The threshold time ratio for keratitis formation with and without eye drops is above 0.93 considering solar radiation on the earth's surface and above 0.65 considering radiation from arc-welding, respectively. DISCUSSION: The transmission spectrum of the eye drops under realistic conditions does not show a protective effect against solar UV radiation. However, there exists reduction of UVC radiation in the spectral range typical of artificial UV sources such as arc-welding. We cannot recommend the application of these eye drops as an UV-protective aid against eye damage by solar UV radiation.

Eye↗
PubMed1995

Keratitis solaris and sunbeds.

Keratitis solaris is caused by ultraviolet radiation in the range 200-320 nm. The threshold dose for keratitis solaris is 40 J/m2 for short-term exposure. We measured the emission spectra of 22 sunbeds in the range 250-500 nm with a high-resolution double monochromator and calculated the exposure times for the threshold dose of keratitis solaris. Depending on the type of lamp used, the exposure times ranged from 90 s to 3.5 h. Lamps with short exposure times for keratitis solaris can induce keratitis solaris if protective goggles are not used (e.g., to achieve a uniform tan of the eye area) and if the eyes are opened briefly several times, perhaps, to look at a watch. Generally, sunbed users have no way of ascertaining the lamp type or its emission spectrum and of determining the exposure time for the threshold dose of keratitis solaris.

Cornea↗
PubMed1994

Spectral transmission of the optical media of the human eye with respect to keratitis and cataract formation.

The spectral transmissions of cornea, aqueous humour, lens and vitreous humour of human eyes were measured in the range from 250 nm to 800 nm in 1 nm steps using a high resolution double monochromator. Cornea and lens are good cut off filters; 1% transmission was measured in various cornea samples between 291 and 298 nm, and in different lenses between 389 and 414 nm. Aqueous humour and vitreous humour showed high transparency (80%) at lambda > 320 nm. The wavelength range of keratitis effective irradiance was found to be completely within the wavelength range of absorption of the cornea, that of cataract effective irradiance was found to be at the short wavelength end partly outside the wavelength range of absorption of the lens. It may therefore be supposed that the action spectrum of cataract obtained by animal experiments is applicable to the human eye only with certain reservations.

Absorption↗
PubMed1993

Biological effectiveness of solar UV radiation in humans.

Solar UVB radiation is prejudicial to the health of humans in a number of ways. Erythema and photodermatoses are acute reactions of the skin; keratitis and conjunctivitis are acute reactions of the eye. Various types of skin cancer, accelerated aging of the skin, and cataract formation in the crystalline lens are reactions that appear with great latency. UV radiation can also cause damage to the immune system and DNA. For the period 1981-1991, an increase in erythemal effective UVB radiation of +(7 +/- 4)% per decade was measured in a non-polluted high mountain area (Jungfraujoch, 3576 m a.s.l., Switzerland). This increase is related to a decrease in stratospheric ozone. The effects on human health are discussed. A 10% ozone reduction increases non-melanoma skin cancer by 26% and cataract by 6 to 8%.

Climate↗
PubMed1992

[Effects of changes in total ozone on solar UV-B radiation and the biosphere].

As a consequence of anthropogenic air pollution the total ozone content in the atmosphere on the northern hemisphere has slightly defined over about 20 years. This is accompanied by an increase in the biologically very effective solar UV-B-radiation. The damage of microorganisms and plants by an increase to UV-B-radiation is generally well known, but at the moment it cannot be expressed quantitatively. A consequence of increased UV-B-radiation for human beings would be an increased number of skin and eye damages. An ozone reduction by 1% would produce an increase in the 2 to 3% incidence of skin melanoma.

Air Pollutants↗
PubMed1990

Indication of increasing solar ultraviolet-B radiation flux in alpine regions.

Measurements at the Jungfraujoch High Mountain Station (Swiss Alps, 47 degrees N, 3576 meters above sea level) indicate that there has been a slight increase of about 1 percent per year in the flux of solar ultraviolet-B radiation (290 to 330 nanometers) since 1981. A Robertson-Berger detector was used to measure solar erythemal radiation. The increase can be related to a long-term ozone depletion.

Altitude↗
PubMed1989

[Differential diagnosis of ophthalmologic syndromes using a computer program].

A Fortran program which can be run on IBM-compatible personal computers has been written for the differential diagnosis of ophthalmologic syndromes. The user enters the symptoms observed and the computer displays a list of syndromes in which these symptoms occur. The program at present covers 219 syndromes and 1094 symptoms, and can be expanded. Its use is expected to make differential diagnosis and the scientific clarification of syndromes easier.

Computer Systems↗
PubMed1989

Chernobyl fallout on Alpine glaciers.

Measurements of the gross beta activity of snow samples from four Alpine glaciers contaminated by radioactive fallout from the Chernobyl nuclear accident and a gamma-spectrum analysis of selected samples are reported. The results are discussed with respect to possible risks to the population from using meltwater from these glaciers as drinking water.

Accidents↗
PubMed1989

Differential diagnosis of ophthalmic syndromes using a computer program.

A Fortran computer program has been written for the differential diagnosis of ophthalmic syndromes. Input for the program are the observed symptoms and the result is a list of syndromes relevant to one or more of the symptoms. The program was written for the Control Data Cyber 840 at the Computer Center of the University of Innsbruck, which is connected permanently by terminals to institutes. A second version of the program has been adapted for IBM-compatible personal computers. At present, the program includes 219 syndromes with their individual symptoms. However, it is possible to supplement or alter the list of syndromes and symptoms. The use of this computer program is expected to make the differential diagnosis easier and to simplify and improve the scientific clarification of syndromes.

Diagnosis, Computer-Assisted↗
PubMed1988

Displacement of Chernobyl fallout in snow layers of temperate Alpine glaciers.

Measurements of the gross-beta-activity and a gamma-spectrum analysis of radioactive fallout from Chernobyl distributed in vertical snow profiles on an Alpine glacier were carried out. Samples were collected in summer 1986 and in summer 1987. A displacement of isotopes to depths of approximately 6 m was observed. The mean activity per unit area amounts to 10.4 and 6.6 kBq m-2 for samples from 1986 and 1987, respectively, both values corrected to 1 May 1987. Isotopes with half-lives shorter than 110m Ag (250 days) could no longer be detected in 1987.

Accidents↗