Lincoln Plaza
Auditorium, First Floor
400 "P" Street
Sacramento, CA

October 11, 1991
8:30 a.m.



91-9-1 Public Hearing to Consider Amendments to 001
Regulations Regarding the State 24-Hour Ambient
Air Quality Standard for Sulfur Dioxide.

91-9-2 Public Meeting to Consider Research Proposals: 070

**PLEASE NOTE: Item 91-8-2, scheduled to be heard October 10,
1991, was heard today--the SECOND item.

ITEM NO.: 91-9-1

Public Hearing to Consider Amendments to Regulations Regarding
the State 24-Hour Ambient Air Quality Standard for Sulfur


The staff recommends that the Board amend sections 70100 and
70200, and repeal section 70201 of the California Code of
Regulations. These changes would revise the State 24-hour
ambient air quality standard for sulfur dioxide by: lowering the
numerical value of the standard from 0.05 parts per million (ppm)
to 0.04 ppm; changing the basis for determining violations of the
standard to "not to be exceeded" (rather than "equal or exceed");
and uncoupling the standard from the current requirement of
concurrent exceedance of either the total suspended particulate
matter standard or the ozone standard.


Long-term exposure to sulfur dioxide has been associated with
adverse respiratory health effects, including an increased
incidence of respiratory symptoms and disease, decrements in
respiratory function, and an increased risk of mortality from
respiratory or cardiovascular disease. Currently, the 24-hour
sulfur dioxide standard is a combination standard; it is violated
when the 24-hour averaged parts per million (ppm) at the same
time as either the oxidant standard of 0.10 ppm (measured as
ozone and not to be equaled or exceeded) or the total suspended
particulate matter (TSP) standard of 100 micrograms per cubic
meter (ug/m3) is violated. The combination standard was adopted
in 1977.

The ARB staff periodically reviews existing state ambient air
quality standards to ensure that they reflect current scientific
knowledge. Staff has reviewed the 24-hour sulfur dioxide
standard and has review the health effects of sulfur dioxide
exposure. The DHS finds that epidemiological studies demonstrate
an association between long-term exposure to sulfur dioxide
(24-hour exposures or longer) and adverse respiratory health effects.
These effects include decreased respiratory function, an
increased incidence of respiratory symptoms and disease, and an
increased risk of mortality. The DHS finds that the data from
the epidemiological studies are adequate to support a 24-hour
sulfur dioxide standard that is not coupled to particulate matter

Based on the data, the DHS finds exposure to sulfur dioxide for
24-hours at or above levels of 0.06 ppm is associated with the
adverse respiratory health effects discussed above (a "low
adverse effects" level). Further, DHS finds that sulfur dioxide
concentrations of 0.04 ppm and below represent a "no adverse
effects" level.

The effects seen in the epidemiological studies were probably not
caused by sulfur dioxide alone; rather, sulfur dioxide serves as
an effective and useful surrogate for other related pollutants
(such as acid, sulfates, or particulate matter) in addition to
itself that occur in polluted atmospheres.

Because of methodological difficulties with the study that
originally supported the combination sulfur dioxide/oxidant
(measured as ozone) standard, the basis for that standard is
weakened, and the staff and the DHS recommend rescinding it.


The proposed changes to the 24-hour ambient air quality standard
for sulfur dioxide, alone, will have no negative environmental or
economic impacts. Ambient air quality standards establish the
maximum allowable levels of air pollutants. Standards should not
be interpreted as permitting or encouraging the degradation of
air quality cleaner than recognized by the standard to the level
of the standard. Specific emission control measures may be
developed to attain and maintain the level of the standard.
Thus, air quality may be improved with corresponding benefits to
the environment and public health and welfare. Since there are
currently no violations of the 24-hour sulfur dioxide standard
and violations are not expected if the proposed changes are
adopted, additional emission controls are not anticipated as a
result of this action.

ITEM NO.: 91-8-2

Notice of Public Meeting to Consider a Plan for the Control of
Emissions from Marine Vessels.


The staff recommends that the Air Resources Board ("ARB" or the
"Board") approve staff's plan and schedule for the development of
regulations to control marine vessel emissions.


The California Clean Air Act of 1988 (Stats 1988 Ch 1568; "the
CCAA"), in Health and Safety Code Sections 43013(b) and 43018(d),
grants the ARB authority to regulate emissions from off-road
vehicles and other mobile sources in order to reduce emissions of
oxides of nitrogen (NOx), hydrocarbon (HC), carbon monoxide (CO),
particulate matter (PM), and toxic air contaminants (TAC), to
contribute to the expeditious attainment of state ambient air
quality standards and to reduce toxic emissions. The CCAA
requires the ARB to hold workshops by January 31, 1991 and to
schedule a public hearing to consider proposed regulations by
November 15, 1991.

To fulfill this statutory requirement, the staff has prepared a
plan for developing regulations to control marine vessel exhaust
emissions. The plan identifies those control measures the staff
considers feasible, and ready for regulatory development. Upon
approval by the Board, the staff will develop a regulatory
proposal for consideration at a future Board hearing. No
regulations are proposed for adoption at this time.

A recently revised inventory has shown that there are
approximately 22,500 marine vessels that either visit California
ports or occupy the California coastal waters on a yearly basis.
The emissions from these marine vessels operating in California
Coastal Waters (CCWs) (i.e., those waters up to 100 miles off the
coast where emissions affect onshore air quality) represent
approximately 10 percent, or 412 tons per day, of NOx and 37
percent, or 226 tons per day, or oxides of sulfur (SOx) emissions

The staff is proposing several regulatory options to control
emissions from marine vessels including emission standards,
operational changes and a market based control (MBC) strategy. A
two day public workshop was held with the marine industry in
November, 1990, to discuss emission control technologies,
operational changes and cost impacts. Subsequent individual
workshops were also held. Promising control technologies include
fuel injection timing retard, selective catalytic reduction, the
use of cleaner fuels, and reduced vessel speed.

A new approach being investigated is the MBC strategy. The MBC
strategy combines an emissions averaging program with marketable
emissions permits. An emissions averaging concept is a
convenient way to label an emissions control strategy where the
total emissions from a number of sources are limited to a maximum
allowed amount, but emissions from the individual sources can
vary. The emissions average could be a declining value permit
system such that the allowable emissions decrease at some
specified percentage, such as 5 percent of the baseline
inventory, each year. The permitted levels would be based on a
determination of the percent control believed reasonable and
achievable, or on the overall emission reductions required to
achieve California air quality standards. The benefit of MBC is
that it provides industry with a greater degree of flexibility in
determining the specific method(s) to achieve the required
emissions reductions.

Enforcement of marine vessel MBC regulations would be difficult
because there are so many different types of commercial marine
operations. Staff is considering several different parties to
manage an emissions averaging program including shipping lines,
terminal operators, and the port authorities.


Regulations can be developed to significantly reduce marine
vessel exhaust emissions. Emission reductions of at least 50
percent for in-use marine vessels appear to be feasible and cost-effective,
using the techniques discussed above. The staff believes that the
appropriate regulatory language can be prepared and presented to the Board
for consideration within the next year.