CALIFORNIA AIR RESOURCES BOARD
Auditorium, First Floor
400 "P" Street
November 12, 1987
87-14-1 Public Hearing to Consider the Adoption of a 001
Regulatory Amendment Identifying Ethylene Oxide
as a Toxic Air Contaminant.
87-14-2 Public Hearing to Consider Amendments to 694
Regulations Regarding the State Ambient Air
Quality Standard for Oxidant.
a. Closed Session
1. Personnel (as authorized by State Agency Open Meeting
Act, Govt. Code Sec. 11126(a).).
2. Litigation (Pursuant to the attorney-client privilege,
Evidence Code Sec. 950-962, and Govt. Code Sec.
b. Research Proposals
c. Delegations to Executive Officer
ITEM NO.: 87-14-1
Proposed Identification of Ethylene Oxide as a Toxic Air
The ARB staff recommends that ethylene oxide be identified as a
toxic air contaminant for which there is not sufficient available
scientific evidence to support the identification of an exposure
level below which no significant adverse health effects are
In accordance with the provisions of Health & Safety Code Section
39650 et seq, the ARB staff, after consulting the Department of
Health Services (DHS), selected ethylene oxide for the Board's
consideration for listing as a toxic air contaminant. The staff
selected ethylene oxide because it has been identified by the
international Agency for Research on Cancer as an animal
carcinogen and a probable human carcinogen, it is emitted from
many sources in the state, and no significant reduction in public
exposure is expected to result from atmospheric removal
As required by Health and Safety Code Section 39661, a report was
prepared jointly by the DHS and ARB staffs reviewing the health
effects and anticipated exposure levels of ethylene oxide. The
Scientific Review Panel, which was established by Health and
Safety Code Section 39670, reviewed the report. The Scientific
Review Panel found that the ethylene oxide report is without
serious deficiency and submitted its written findings to the
Board. The Scientific Review Panel has recommended that the Air
Resources Board list ethylene oxide by regulation as a toxic air
contaminant, and found that based on available scientific
information, an ethylene oxide exposure level below which
carcinongenic effects are not expected to occur cannot be
SUMMARY AND IMPACTS OF PROPOSED BOARD ACTION
The identification of ethylene oxide as a toxic air contaminant
will not in itself have any environmental and economic impacts.
However, specific control measures may be developed subsequent to
identification. Analyses of potential environmental and economic
impacts will be included in the consideration of such control
ITEM NO.: 87-14-2
Recommendation for Ambient Air Quality Standard for Ozone based
on Health Effects and on Vegetation and other Welfare Effects.
The Air Resources Board staff recommends that a new standard be
adopted to reflect the effects of ozone on California public
health and vegetation including crops, natural plant communities,
ornamental plants and on materials.
Staff recommends that a definition of ozone be added to Section
70100, Title 17. Staff also recommends that the "Substance,"
"Concentration and Methods," "Duration of Averaging Periods," "Most
Relevant Effects" and "Comments" columns of Title 17, Section
70200, Table of Standards, be amended to include significant
facts and findings. Staff also recommends that two asterisks be
placed in the "Concentration and Methods" column indicating that
this standard is violated when concentrations exceed those set
forth in the body of the regulation. During the 1982 AB 1111
review, the Board decided to change the basis for determining
standards violations to an "exceed only" policy as standards are
reviewed or adopted. Under this new compliance definition, a
0.09 ppm ozone standard would be essentially equivalent to the
existing 0.10 ppm oxidant standard. The Department of Health
Services (DHS) recommends that the Board adopt an ozone standard
of 0.08 ppm averaged over one hour.
The current oxidant standard is primarily a health-based
standard, even though protection of health and welfare
(vegetation effects) were considered when the standard was set.
Since the time the standards was set in 1969, much additional
information has been developed on harm to health and injury to
vegetation; as well as on crop yield and ultimate economic
effects. In addition, information regarding effects on native
plant communities and ornamental plants is available.
The DHS recommendation is based on a lowest observed level of
adverse health effect of 0.12 ppm, plus a margin of safety. Both
DHS and ARB agree on the lowest adverse effect, and both agencies
agree a margin of safety is necessary because of uncertainties as
to the precise level at which human health effects occur.
However, ARB and DHS staff differ in their judgement of the
appropriate margin of safety which should be incorporated into
the standard. Upon reviewing the evidence, it is the conclusion
of the ARB staff that a standard of 0.09 ppm, averaged over one
hour (the equivalent to the existing standard) would protect the
public health from ozone exposure with an adequate margin of
safety relative to the level at which acute pulmonary effects
occur. A standard of 0.08 or 0.09 ppm, if achieved, would
prevent adverse effects on California public health, and place an
acceptable upper limit on the amount of harm allowed to
vegetation and the economy.
A standard of 0.08 or 0.09 ppm would also minimize environmental
impacts. Increases in the rate of change in species number and
diversity may still occur when native plant communities are
exposed to ozone below the level of the proposed standard.