An environmental engineer is evaluating two different gaseous radioactive tracers, Tracer P and Tracer Q, to detect underground leaks in a municipal water main. Both tracers are introduced into the pipeline with the same initial activity.
Figure 1 shows how the activity of a sample of each tracer decays over time.
Suggest one reason why Tracer Q could pose a greater environmental or public health risk to the local area if a leak occurs compared to Tracer P.