You are right that from the ground it will be very difficult to notice everything. Relatively recently, a monitoring system has been created that uses UAVs for this purpose. That is, from the air will monitor the situation by UAV operators who monitor what the camera captures. Or you yourself can watch where the UAV is flying and at the slightest smoke you can call the fire department. Also on such UAVs installed sensors, which allow you to monitor air pollution and if not noticed by the man, the combustion products will be detected by the sensor and will immediately give the result of air pollution. Here is the air monitoring system Menatir that I found. I think it's the perfect option. Which will allow you to spot fires in advance.