---

ARB, SCAQMD Measure Pollutants in Vehicles

11 June 1999

ARB, SCAQMD Measure Pollutants in Vehicles

    SACRAMENTO, Calif., June 10 -- The California Air Resources
Board (ARB) and the South Coast Air Quality Management District (SCAQMD) today
announced that exposure to some air pollutants and toxic compounds may be ten
times higher inside vehicles than in ambient air.  The two-year,
$440,000 study is the first-ever to gather particulate data inside vehicles
and the first to collect real-time information under a range of traffic and
driving conditions.
    Dr. Alan Lloyd, ARB Chairman said, "We're learning that peoples' highest
daily exposure to air pollutants may be during their commute to and from work.
Also, we have concerns about the potential impact on bus riders, especially
children.  Therefore, I've asked the ARB staff to collect more data to
evaluate the risks."
    The study's objectives were to measure motorists' personal exposure to
common motor vehicle pollutants in Los Angeles and Sacramento, two areas that
have high levels of motor vehicle-generated air pollution.  Funded by the ARB,
with support from the SCAQMD, the study measured the direct exposure to motor
vehicle occupants from gaseous pollutants, diesel soot and other fine
particles.
    As part of the study, ARB researchers also began looking at pollutant
levels inside school buses.  Future ARB research may include projects that
will better define the pollutant levels to which children are exposed while
traveling to and from school.
    Researchers found levels of hydrocarbons and carbon monoxide were between
two and ten times higher inside vehicles than at roadside or fixed monitoring
stations.  Researchers also found similar levels of toxic compounds such as
benzene, 1,3-butadiene, ethyl benzene, toluene, xylene and MTBE, all
considered toxic by the ARB and USEPA.  The variations depended on the
pollutant, the type of road and the level of traffic.
    Researchers found that as much as one-half of the pollutants inside test
cars were emitted by the vehicle ahead.  In general, levels of toxics and
other pollutants are higher inside vehicles than in outdoor ambient air
because cars are surrounded by emissions from other vehicles on freeways and
streets.
    "We know that air pollutants in ambient outdoor air pose a health risk to
Southland residents," said Barry Wallerstein, SCAQMD Executive Officer.  "This
study confirms that commuters face an additional risk breathing the polluted
air inside their cars."
    According to the research data, motorists who used air conditioning
systems and those who drove with their air vents open were exposed to similar
amounts of pollution.  Researchers learned that people who use carpool lanes
were exposed to pollutant levels well below those measured in other traffic
lanes, possibly because carpool lanes are less congested and further removed
from the truck lanes.
    The Air Resources Board is California's air pollution control agency.  The
ARB's mission is to promote and protect public health, welfare, and ecological
resources through effective reduction of air pollutants while recognizing and
considering effects on the economy.  The ARB oversees all air pollution
control efforts in California to attain and maintain health based air quality
standards.