Abstract: A method of assaying the reactive oxidants present in a smoke sample, the method comprising: preparing solution including a reductant; passing smoke through the solution; detecting the concentration changes of the probe in the presence of the smoke sample over time; and calculating the concentration of reactive oxidants of the smoke sample from the concentration changes of the reductant in the presence of the smoke sample. A method of assaying the reactive oxidants present in a smoke sample, the method comprising: preparing a solid material containing a reductant; passing smoke through the solid material; detecting the concentration changes of the reductant in the presence of the smoke sample over time; and calculating the concentration of reactive oxidants of the smoke sample from the concentration changes of the reductant in the presence of the smoke sample.