Every year there are a lot of fires in Latvia in the residential sector and in a great number of fires people are killed. Fires often break out in the middle of the night or early in the morning, when people sleep and do not feel smoke starting to spread through housing. Fatal fires are very common fires with a small area of burning when people die inhaling poisonous burning products without even waking up. Thus, the autonomous smoke detector is compulsory equipment that should be in every home. In the event of a fire, it helps inform the inhabitants of the fires that have broken out and provides them with the opportunity to evacuate from filled with smoke rooms in good time. And time shows that smoke detectors are effective means and there are several cases where people have only saved themselves from burning homes due to hearing the sound of the smoke detector. Meanwhile, as the mandatory installation of a smoke detector in each dwelling was introduced, the Latvian State Fire and Rescue Service notes that there are more and more cases where smoke detectors are installed in dwellings, but do not work or perform their primary and sole function – to inform people of the smoke by a high sound signal. The authors of the article examined the reasons for the failure of smoke detectors, which have been identified in other countries and conducted an experiment where the effect of the dirtiness of the smoke detectors on the failure of them when smoke occurs, was checked. As well as a survey among residents of Latvia was conducted regarding whether they had installed smoke detectors in their dwellings, how much and in what rooms the detectors had been installed, what prompted them to purchase smoke detectors, whether before installation people had read the instructions for use and were informed how to correctly install smoke detectors, whether they know that for smoke detector maintenance inspection of them had to be performed and whether people did that. As part of this study, the authors examined how the service time of smoke detectors changes and whether it changes if the smoke detector is operated in different rooms and for different time periods, but their regular cleaning from dust and other dirt is not done. As well as it was checked how quickly the smoke detector would start working if the fire breaks out in the next room and the time for a person to evacuate from those rooms was calculated. The operational efficiency of the autonomous smoke detector was examined and recommendations for effective extension of its operational capacity were put forward.