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Laboratory Evaluation of Real-Time Smoke Particulate Monitors
Monitoring smoke particulate concentrations from prescribed burns and wildland fires is becoming increasingly important. Because prescribed burns are more prevalent, the impact of their smoke on communities is more significant. In addition, the number and intensity of wildland fires are increasing, especially in the West, causing Federal, State, county, and local officials to issue more frequent and more detailed smoke advisories and health warnings.
Determining smoke particulate concentrations in real time is key in assisting air quality officials. Many real-time particulate concentration monitors use optical (light-scattering) measurements to estimate particulate concentrations. Other monitors use attenuation devices or other means to estimate concentrations. Several years ago, the U.S. Department of Agriculture, Forest Service, Missoula Technology and Development Center (MTDC) was asked to evaluate commercial real-time particulate concentration monitors. The evaluation included studies that placed real-time samplers beside an approved Federal Reference Method (FRM) gravimetric sampler in a laboratory and in a field setting. The goals of these tests were to determine the accuracy of the monitors when measuring smoke particulate, to determine correction algorithms to adjust values from the instruments for more accurate results, and to assess such things as ease of use, reliability, and portability.
Laboratory tests were conducted in the Rocky Mountain Research Station’s Fire Sciences Laboratory (FSL) in Missoula, MT. The real-time and FRM samplers were on a platform 55 feet above the floor of the laboratory’s burn chamber. Smoke was generated by burning small piles of pine needles near the floor. Fans mixed the smoke in the chamber.
Two reports, Laboratory Evaluation of Two Optical Instruments for Real-Time Particulate Monitoring (9925–2806–MTDC), and Evaluation of Optical Instruments for Real-Time Continuous Monitoring of Smoke Particulates (0025–2860–MTDC) detail the results of those tests (figure 1).
![[photo] 3 MTDC Pub covers](images/fig01.jpg)
Figure 1—Three reports (9925–2806–MTDC, 0025–2860–MTDC,
and 0125–2832–MTDC)
detail the evaluations of several
real-time
smoke particulate monitors in laboratory and field environments.
Field tests of the real-time instruments were conducted to determine whether the laboratory results could be replicated in the field. Again, the instruments were placed beside the FRM monitor to allow comparative results. In 1998 and 1999, the instruments were set up downwind of prescribed burns around western Montana. Results from these tests are detailed in Evaluation of Optical Instruments for Real-Time Continuous Monitoring of Smoke Particulates. In the summer of 2000, the western part of Montana experienced huge wildland fires that filled the valleys with smoke for nearly the entire month of August. We placed instruments in Missoula and Hamilton, MT, during that time. Results from these field tests are described in Real-Time Smoke Particulate Sampling, Fire Storm 2000 (0125–2832–MTDC).
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