In recent years, the contamination of toxic gases in society is a very controversial problem because of the various consequences and effects they generate on health. There are several studies which highlight that the main polluting gases to the environment such as carbon monoxide, lead, cadmium, among others are the main causes of the increase in various acute diseases, such as pneumonia, or chronic diseases, such as cardiovascular diseases or lung cancer. That is why, faced with this problem, this research work proposes a monitoring system that determines the concentration of toxic gases, in such a way that it can contribute as an informative medium which can be implemented in various focused points where high rates of pollution are concentrated. The system has a very efficient MQ 135 gas sensor which includes a reading of 5 to 600 ppm (parts per million) at 3m with a temperature of 25ºC. It should be noted that it is important to keep the sensor on 24 hours beforehand to obtain a correct reading. Thus, concluding that this system of toxic gases can be easily applied to society because it is economical and because it has a free software which will be responsible for informing through a web server the level of ppm that you want to analyze at a certain point.