Hydrogen applications are still fairly unknown. That is why it is understandable that some residents and those in the area are concerned about their safety. Hydrogen, like natural gas, is flammable. Fortunately, hydrogen does not simply ignite. That requires a concentration of 4% or higher. Plus, a flame or spark to ignite it. Because hydrogen naturally rises extremely quickly (H2 is the smallest and lightest element in the universe) a concentration of 4% in the outside air hardly ever occurs. Good ventilation is required in closed-off areas.