Quantitative risk assessment from exposure to diesel emissions was performed by the State of California in a process that led to the identification of diesel particulate emissions as a toxic air contaminant in August 1998. Here in San Diego, the City's Environmental Services Department is demostrating such leadership. The city's trucks are the biggest remaining source of air pollution driving in every neighborhood on a weekly basis. LNG is the only hydrocarbon that does not react photochemically to contribute to the formation of ground-level ozone pollution. Each LNG truck will remove the equivalent of 100 cars worth of pollution off the road emitting 35 percent less of the cancer-causing nitrogen oxides.
Natural gas is a byproduct of landfills and either escapes into the air or is burned off.
Hays is investing in a process to recover escaping landfill gas, remove other pollutants and convert it into LNG for vehicle fuel. This cycle will significantly reduce the amount of pollutants such as carbon dioxide, carbon monoxide, and oxides of nitrogen and reduce the city's contribution to global warming. This project will also explore the potential for converting green waste collected by the City as well. After the conversions, San Diego will have the largest municipal fleet using LNG in the country. According to the grant requirements, the conversions must take place within two years and the vehicles must be operated on natural gas for at least five years.