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Worldwide people are exposed to toxic ultrafine particles (UFP, with diameters (dp) less than 100 nm) and nanoparticles (NP, dp < 50 nm) under a variety of circumstances. To date, very limited information is available on human exposure to freshly emitted UFP and NP while traveling on major roads and freeways. We report in-cabin and outdoor measurements of particle number concentration and size distributions while driving three vehicles on Los Angeles freeways. Particle number concentrations and size distributions were measured under different vehicle ventilation settings. When the circulation fan was set to on, with substantial external air intake, outside changes in particle counts caused corresponding in-cabin changes approximately 30–60 s later, indicating an maximal air exchange rate of about 120–60 h-1. Maximum in-cabin protection (∼85%) was obtained when both fan and recirculation were on. In-cabin and outdoor particle size distributions in the 7.9–217 nm range were observed to be mostly bimodal, with the primary peak occurring at 10–30 nm and the secondary at 50–70 nm. The vehicle's manufacture-installed particle filter offered an in-cabin protection of about 50% for particles in the 7–40 nm size range and 20–30% for particles in the 40 to ∼200 nm size range. For an hour daily commute exposure, the in-vehicle microenvironment contributes approximately 10–50% of people's daily exposure to UFP from traffic. [ABSTRACT FROM AUTHOR]

Investigates the effect of emissions control strategies on the size and composition distribution of urban aerosol in Los Angeles, California. Presentation of the changes in the size and composition distribution of airborne particles; Emissions inventory summary; Specific emissions control measures for primary particulate matter.

The article reports that the United States has slowly cast aside its role as a leader in the field of environmental assessments because successive administrations have chipped away at the scope of the National Environmental Policy Act (NEPA) since it was signed into law by President Richard Nixon in January 1, 1970. The NEPA was enacted after the news coverage on the oil spill in Santa Barbara, California and the Cuyahoga River fire in Ohio. NEPA protections have slowly been taken away by Congress and by federal agencies which have issued the rules.

The article reports that in May 2005, Washington became the ninth U.S. state to adopt vehicle tailpipe standards that are tougher than the federal government's. Washington's standards would not go into effect until Oregon approves the low-emission vehicle (LEV) rules for its automobiles, which could happen in the next few years. More controversial is California's update of its LEV-II rules in September 2004 which addresses greenhouse gases. LEV supporters are delighting in what they call the creation of clean-car corridor.

States that California regulators have proposed tighter emissions requirements for mini-vans, sport utility vehicles, and other light vehicles. Information on the effect of this amendment; Reasons for the amendment; Details on the amount of light trucks sales for 1997; Comments from Ann Misinkoff, of the Sierra Club.