(Horwell 2005) reports that light contamination of the hydrogen sulfide test strips (using black and white photographic film) will not alter the results of the test.
"Hardiness of the teststrips: they can be washed with cold water and exposed to light without loss of fidelity: "No signiﬁcant difference in measured sulﬁde was obtained between the different ﬁxing/washing procedures tested, giving conﬁdence that ﬁeld samples can be quite robustly handled, and washed, in cold water, to remove any particulate surface contaminants.""
This is surprising, as the strips show visible color change if exposed to light - yet communication with a fellow researcher has confirmed that the strips are quite hardy and results will not be skewed by exposure to light. - fixing with a photographic fixing agent will remove any visible color change due to light.
For this test environment three (3) prepared strips will be placed in a darkened environment while three (3) will be exposed to light. All six (6) test strips will otherwise be exposed to similar environmental factors (temp., humidity, atmospheric conditions).