The object of this study is the dynamics of hazardous parameters of the gas environment when materials are ignited in the premises. The task addressed was the early detection of fires in the premises. It is proposed to resolve this issue on the basis of using an assessment of the coherence of frequency components in the third-order spectrum relative to the dynamics of hazardous parameters of the gas environment. The results indicate the nonlinear nature of the dynamics of hazardous parameters of the gas environment both in the absence and in the presence of fires. It was established that the assessment of the coherence of the frequency components relative to the considered triplets in the third-order spectrum contains information on the ratio of order to chaos in the dynamics of hazardous parameters of the gas environment. This information can be used to reliably detect fires. It was found that when the test materials in the form of alcohol, paper, wood, and textiles are ignited, the ratio of order to chaos in the temperature and CO dynamics in a gaseous medium is halved. It was established that the average values for frequency indices from 0 to 20 of the coherence of the frequency components of the dynamics of hazardous parameters on the ignition interval of test materials are in the range from +0.005 to –0.187. At the same time, in the interval of absence of ignition of test materials, the average values of the coherence assessment for frequency indices from 0 to 20 are in the range from +0.48 to +0.022. The reported results generally indicate the prospects and further development of studies into the coherence of the frequency components of the third-order spectrum for the dynamics of hazardous parameters of the gas environment in order to detect fires in the premises