# IoT-Enabled Gas Sensors: Technologies, Applications, and Opportunities
## 3 Internet of Things (IoT) Verticals Opportunities and Economic Impact  
Environmental gas detection and measurement had become essential in diverse fields and applications, from preventing accidents (including life-saving), avoiding equipment malfunctions, warning about air pollution, and helping hospital patients [17; 18; 36; 37; 83]. Considering this scenario, the development of a sensor capable to attend these demands being able to collect information about numerous gases is crucial to avoid all the losses caused by unwanted gases.  
The costs attributable to gas leakage are enormous: from the loss of production in the food industry, to reconstruction of buildings caused by flammable gas leakage followed by explosions, and the healthcare expenses to treat patients who suffered injuries by gas poisoning [17; 18; 36; 37; 83]. In the United States of America (USA) alone, the annual costs linked to carbon monoxide intoxication is over $1.3 billion, and the deaths as a consequence of this gas leakage are over 2000 per year [19; 37].  
Other gases represent an imminent risk to the population and to the environment, being linked to cancer, cardiovascular diseases, cognitive disabilities and respiratory failure [19; 21; 39; 84; 85; 86; 87; 88]. Gas leakage can reach large proportions, affecting entire neighborhoods, or even cities. The magnitude of the environmental impact of such an incident can be catastrophic in terms of deaths and evaded area [17; 18; 39; 83].  
It was estimated by the International Labor Organization (ILO) that 4% of the Gross World Product (GWP) is expended on labor accidents and the percentage is higher when taking in account work-related health problems [16]. Another study has shown that, in a period of 40 years, accidents caused by gas leakage, fires, and explosions on oil sub-products storage tanks represented 90% of the accidents in this field, and human error were linked with 30% of all kind of incidents in the same industry. The same study showed that the average cost per casualty of the 10 most devastating incidents on this industry was around $114 million, reaching $330 million in the most expensive disaster up until publication [83].  
Together with the development of a multi-gas sensor, the information collected by these devices should be easily available to the users and also to other devices that could use the provided data to contribute to the best experience to the users of this system as well as to decreasing avoidable costs, making possible investments on demanding areas [7; 10; 13; 89].  
The detection of gas leakage can be crucial to avoid all the health and environmental problems, not only by alerting people about incidents, giving them time to evade the area, but also by providing information to actuators that can act in order to stop the leakage and mitigate the consequences [17; 18; 36; 39; 83; 84; 85; 86; 90; 91; 92; 93].  
With the paradigm of the IoT, it is expected the number of connected devices will reach 50 billion by 2025 with an estimated increase of $1 to 2.5 trillion USD on the GWP by the same year [11; 13; 89]. The sectors (IoT verticals) where the impact of the new technologies will be introduced and the use of a multi-gas smart sensor can be seen on Figure 1.  
A multi-gas sensor together with other devices integrated over IoT networks will have a positive impact on the sectors (IoT verticals) previously shown, allowing new investments by governments, companies, and people in sectors might demand more attention. The number of accidents related with the presence of determined substances should decrease, reducing the risks of specific activities, causing a positive effect on avoidable costs, and repairing the damage caused by such incidents [19; 36; 37; 55].