Environmental monitoring programs are important for industries that work with gasses that may be dangerous or may represent a risk for workers or the environment in general. These industries are obligated to present a risk assessment to avoid any potential danger. To do this, there are computational programs that can model any leak and calculate the damage that may cause. A problem that can be presented for this program is that they assume that the gas is always moving but there are some occasions that the gas may be not moving because there is not air flux due to a closed space or because the gas may be too heavy. So, what happened when the gas remains static? Here we present some equations that may describe this situation to teach them to a new generation of environment and risk assessment professionals.