The location in which the aircraft is operating determines how hazardous the environment is in terms of the exposure to corrosive substances. Atmosphere high in moisture is more susceptible to corrosion and traditionally costal or marine environments create the most severe conditions. The salinity from the ocean contributes chloride to the air which exacerbates the moist atmosphere. However areas where geothermal activity is present also generate chlorides in addition to corrosive gases. Other environments that warrant additional concern are regions where the atmosphere is high in pollutants as these chemicals often exhibit corrosive characteristics.