Canine Olfaction Research and Education Lab, Davis College of Animal and Food Science, Texas Tech University, Lubbock, Texas, United States of America.
Forensic Analytical Chemistry and Odor Profiling Lab at Texas Tech University, Lubbock, Texas, United States of America.
PLoS One. 2024 Sep 25;19(9):e0306817. doi: 10.1371/journal.pone.0306817. eCollection 2024.
Detection canines are deployed to detect explosives in a wide range of environmental conditions. These environmental conditions may have negative impacts on canine capabilities as a sensor. This study leveraged an air dilution olfactometer to present controlled odor concentrations of four different energetic materials (double base smokeless powder, Composition C4, ammonium nitrate, and flake Trinitrotoluene) to dogs working in a range of high temperature, standard, and low temperature conditions with high and low humidity conditions. The air dilution olfactometer controlled concentrations independent of environmental condition. Dogs' detection threshold limits were measured using a descending staircase procedure. We measured dogs' threshold twice for each energetic under each environmental condition. Results indicated heterogeneity in effects based on energetic, but all odors were detected at their lowest concentrations under standard conditions. Smokeless powder detection was reduced under all environmental conditions compared to standard and was least detectable under high temperature and humidity conditions. AN detection was poorest under high temperature high and low humidity conditions. C4 in contrast, was least detectable at low temperatures with high humidity. TNT detection was difficult under all conditions, so decrements due to environmental conditions were not statistically detectable. Additional measures were also found to be associated with detection limits. Under high temperature conditions, correlations were observed between canine mean subcutaneous temperature and detection limits, such that dogs experiencing greater temperature increases showed poorer detection limits. In addition, dog's latency to sample the odor port from the onset of a trial was longest in the high temperature conditions. Longer latencies were also predictive of poorer detection performance. Overall, dogs showed deficits in detection sensitivity limits under all environmental conditions for at least one energetic material when the concentration of that energetic material was not directly impacted by the environmental conditions. These results suggest that behavioral factors related to environmental exposure can have important impacts on canine detection sensitivity and should be considered in operational environments.
检测犬被部署用于在广泛的环境条件下检测爆炸物。这些环境条件可能会对犬类作为传感器的能力产生负面影响。本研究利用空气稀释嗅觉仪向犬呈现四种不同的高能材料（双基无烟药、C4 炸药、硝酸铵和片状三硝基甲苯）的受控气味浓度，犬在高温、标准和低温条件下工作，同时存在高湿度和低湿度条件。空气稀释嗅觉仪独立于环境条件控制浓度。使用下降阶梯程序测量犬的检测阈值极限。我们在每个环境条件下对每种高能材料进行了两次测量。结果表明，基于高能的效应存在异质性，但所有气味在标准条件下都能以最低浓度被检测到。与标准条件相比，无烟药在所有环境条件下的检测都减少了，在高温高湿度条件下最不易检测到。在高温高湿度和低湿度条件下，AN 的检测效果最差。相比之下，C4 在低温高湿度条件下最不易检测到。TNT 在所有条件下都难以检测，因此环境条件造成的衰减在统计学上无法检测到。还发现其他措施与检测极限有关。在高温条件下，犬的平均皮下温度与检测极限之间存在相关性，即体温升高较大的犬表现出较差的检测极限。此外，狗从试验开始到取样气味端口的潜伏期在高温条件下最长。较长的潜伏期也预示着较差的检测性能。总体而言，在至少一种高能材料的浓度不受环境条件直接影响的情况下，犬在所有环境条件下的检测灵敏度极限都表现出缺陷。这些结果表明，与环境暴露相关的行为因素可能对犬类的检测灵敏度有重要影响，在作业环境中应加以考虑。
