Mercury and toxins from pesticides have been detected in the park, as has ozone; these have not been demonstrated to be at sufficient concentrations to greatly impact the ecosystem. Sulfur, nitrogen dioxide and ozone from factories and automobile emissions as well as increased dust and fine particulates from sources such as farming and construction are dispersed into the atmosphere, reducing long-range visibility. Visibilities of up to have been reduced to less than on the worst days due to the increased haze.