California Code of Regulations › Title 17 - Public Health › Division 1 - State Department of Health Services › Chapter 5 - Sanitation (Environmental) › Subchapter 5 - Air Sanitation* › Article 1 - Standards for Ambient Air Quality › Section 30690 - Table of Standards and Explanatory Footnotes

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
(a) Table of Standards
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(b)
					 Footnotes.
(1) Hydrocarbons are a group of
					 substances most of which, normally, are toxic only at concentrations in the order of
					 several hundred parts per million. However, a number of hydrocarbons can react
					 photochemically at very low concentrations to produce irritating and toxic
					 substances. Because of the large number of hydrocarbons involved, the complexity of
					 the photochemical reactions and the reactivity of other compounds such as nitrogen
					 dioxide and ozone, it is not yet possible to establish "serious" and "emergency"
					 levels for hydrocarbons. From the public health standpoint, the concentration of
					 those hydrocarbons which react photochemically should be maintained at or below the
					 level associated with the oxidant index defined in the "adverse" standard.
(2) Ozone, at 1 ppm for eight hours daily for
					 about a year, has produced bronchiolitis and fibrositis in rodents. Extropolation of
					 these data to man is difficult. Functional impairment data have been reported; at
					 1.25 ppm some effect is observed on residual volume and diffusing capacity. The
					 variability of the tests was not reported. Additional data would be needed before a
					 standard is set.
(3) A value of 2.0 ppm
					 of ozone for one hour may produce serious interference with function in health
					 persons and the assumption is made that this might cause acute illness in sensitive
					 persons.
(4) Nitrogen dioxide, at
					 concentrations above 2.5 ppm. causes acute damage to sensitive plants. One ppm for
					 eight hours will produce significant growth reduction, expressed as fresh and dry
					 weight, with no visible lesions of damage. High levels (150-220 ppm) in short
					 exposures produce fibrotic changes in the lungs of man that may end
					 fatally.
(5) Given certain assumptions
					 concerning ventilatory rates, acute sickness might result from a carbon monoxide
					 level of 240 ppm for one hour in sensitive groups because of inactivation of ten
					 percent of the body's hemoglobin. In any event it is clear that when a population
					 exposure limit has been set for carbon monoxide, because of exposure from other
					 sources, community air pollution standards should be based on some fraction of this
					 limit.
(6) Hydrogen sulfide is not known
					 to produce chronic disease in humans but there may be durable sequelae from acute
					 exposures. The disagreeable odor may interfere with appetite in sensitive groups of
					 persons at about 5 ppm. At high concentrations loss of the sense of smell occurs.
					 This has been reported at 100 ppm for exposure lasting two to fifteen minutes.
					 Conjunctivitis and mild respiratory tract irritation have been reported at levels of
					 50-100 ppm for one hour.
(7) Acute
					 sickness and death with neurotoxicity may occur at concentrations of several hundred
					 ppm. It is very unlikely these levels will occur in community air
					 pollution.
(8) A sulfuric acid mist
					 level of 1 mg/M3 with an average particle size of 1
					 micron will produce a respiratory response in man. It is not possible to generalize
					 from this fro all air pollution conditions, because under natural conditions,
					 particle size will vary. Only with large droplets would sensory irritation be
					 produced without other physiological effects.
(9) A level of 5 mg/M3
					 of sulfuric acid mist for a few minutes produces coughing and irritation in normal
					 individuals. Presumably, it could cause acute illness in sensitive groups of persons
					 in a period of one hour.
(10)
					 Carcinogens include a few organic compounds such as some polycyclic hydrocarbons and
					 some metals such as arsenic and chromium. Studies on effects of such substances are
					 currently under way, but there are not sufficient data, at present, to set
					 standards. In the meantime, it is recommended that concentrations of carcinogens in
					 air should be kept as low as possible.
(11) Hydrogen fluoride and other airborne
					 fluorides settle upon and some are absorbed into vegetation. When forage crops
					 containing 30-50 ppm of fluoride measured on a dry weight basis are regularly
					 consumed over a long period the teeth and bones of cattle may show changes,
					 depending on age, nutritional factors and the form of fluoride ingested. Such
					 changes may or may not have any economic effect. Fluorides at these levels do not
					 necessarily cause injury to the forage plants themselves. However, injury may be
					 produced in certain species of vegetation upon long term exposure to low levels of
					 atmospheric fluorides.
(12) The
					 irritating properties of hydrogen fluoride in experimental human exposure have been
					 manifested by desquamation of the skin, at concentrations of 2-5 ppm. mucous
					 membrane irritation also occurs from hydrogen fluorides but quantitative data are
					 not adequate to support a standard.
(13)
					 It is clear that lead levels should be set on the basis of average values for long
					 periods. While data are abundant concerning human response to eight-hours-a-day,
					 five-days-a-week exposures, data are insufficient for the effects of the continuous
					 exposure inherent in community air pollution. While laboratory studies will be
					 pursued with vigor, it becomes very important that local agencies collect data on
					 existing lead levels. Since lead exposures are from multiple sources, community air
					 pollution standards should be based on a portion of the total limit for population
					 exposure.