Dealing with diesel.

Hundreds of industrial and commercial facilities in the county and thousands throughout the state will have to start reporting emissions from diesel engines under proposed amendments to the state's toxic hot spots regulation.

The proposal, which the state Air Resources Board unveiled this summer, would require facilities with multiple diesel engines--including backup power generators--to report diesel emissions to both the state board and their local air pollution control agency. In L.A. County, it's the South Coast Air Quality Management District.

Facilities with multiple diesel engines near residences or schools would have to notify the public about the emissions and do a risk analysis of those emissions. Some may have to take additional steps to reduce diesel emissions.

Why the changes? New scientific data have emerged in recent years about the toxicity of diesel emissions at lower levels than previously thought. That led the air board to revamp its reporting requirements under the state's 19-year-old toxic hot spots program, which is designed to monitor emissions deemed toxic at commercial, industrial and government facilities.

Thousands of facilities in Los Angeles County that already are required to report their toxic emissions would have to go back and catalog emissions from diesel sources. But the proposal also takes in many types of facilities that haven't had to deal with the program before. Among these: business parks, telecommunications systems and commercial office towers. These entities either have fleets of diesel vehicles or have backup generators that run on diesel fuel.

These proposed changes, currently in draft form, are set to come before the board in November.

Staff reporter Howard Fine can be reached at [e-mail] or at [phone], ext. 227.