I have done some research about how various lighting works and why fluorescent lights can cause problems. From my reading it appears that normal fluorescent bulbs emit a range of ultra violet light (both UVA and UVB) which is converted to emit visible light. However not all of the UVA/B gets converted and it is this unconverted UVA/B spectrum that causes problems for a whole variety of people.
Good overview of fluorescent lights
Good overview of the various wavelenghts (link provided by Dan)
Studies that indicate how low level UV can affect health
SourcePhotosensitivity to white fluorescent lighting has been demonstrated in 5 patients, 3 with "actinic reticuloid", 2 with solar urticaria. All patients were particularly sensitive to longwave UVR and in some instances, by using filters, it has been possible to demonstrate one spectral region of the fluorescent emission that causes photosensitization, namely 365 nm.
Source:Objective. To determine the prevalence of fluorescent light toxicity in patients with systemic lupus erythematosus (SLE).
Methods. SLE patients were polled about their symptomatic responses to sunlight and cool white fluorescent light. Photometry was used to determine the levels of ultraviolet (UV) emissions from fluorescent lamps.
Results. Thirteen of 30 photosensitive SLE patients described increases in disease activity following exposure to unshielded fluorescent lamps. Photometry indicated that these lamps emit substantial levels of UV-B (280-320 nm) radiation, which is toxic to patients with SLE. Standard acrylic diffusers absorbed this radiation, and their use was associated with almost no patient-reported problems.
Conclusion. Fluorescent lamps, emitting UV-B radiation, induce disease activity in photosensitive SLE patients. Standard acrylic diffusers absorb UV-B radiation and appear to be protective against induction of disease activity with the use of fluorescent lamps.
Study published in the journal of American Journal of Epidemiology
I guess potentially the easiest solution would to substitute the fluorescent light with a suitable alternative such as a standard incandescent bulb as this does not appear to emit the UV wavelength (halogen light apparently do).
Alternatively it appears that there are a number of solutions to blocking UV radiation from fluorescent lights ranging from the use of special filters placed over the light source or special fluorescent tubes such as:
It appears certain filters do a good job of blocking out these UV wavelengths. It is clear that an uncovered UV light is the worst option. The main problem so far has been finding a supplier of these sorts of filters/tubes in the UK.
Other general information and resources
Chart of wavelengths for comparison:
Blue Light-also found in fluorescent lights
Dan from the rosacea support forum provided me with further help regarding blue/violet wavelenghts and so the following is information/links provided by him.
Wavelengths can cause problems for porphyria
"The peak light absorption range for porphyrins corresponds well to the wavelength of light (@400nm) known to trigger photosensitivity reactions in the skin of patients with EPP":
Article discussing PCT and the damaging effects of light in the Blue (400 nm) range:
"The UV light is absorbed by the bulb's fluorescent coating, which re-radiates the energy at lower frequencies (longer wavelengths: two intense lines of 440nm and 546nm wavelength appear on commercial fluorescent tubes) (see stokes shift) to emit visible light.":