PHILIPPE PSAILA / SCIENCE PHOTO LIBRARY PHILIPPE PSAILA / SCIENCE PHOTO LIBRARY
Contamination detection. Two firefighters analysing a contaminated liquid using a strip of chemical reactive paper. They are wearing protective clothing, including breathing apparatus. The strip contains dyes which are soluble in the presence of specific chemicals. The strip will change colour dependending on the type of chemical it is exposed to. While these strips are a cheap and quick method of detection, they can give false-positive readings and so another method of detection is needed to confirm positive results.
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