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MEMORANDUM 

1 JUN 1yy2 

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SUBJECT : Contingency Measures for Ozone and Carbon Monoxide (CO) 

Redesignations 

FROM : 

TO : 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

Office of Air Quality Planning and Standards 

Research Triangle Park, North Carolina 27711 

G .T . Helms, Chief 

Ozone/Carbon Monoxide Programs Branch (MD-15) 

Air Branch Chief, Regions I-X 

Several Regions have asked for specific examples of what a 

contingency plan should contain . In general, a contingency plan 

should identify the measures that the State will adopt and the--

factors that will determine when the measures will be adopted . 

An example of this is attached . The attached example is only one 

approach to the contingency plan ; it is not the only approach . 

If you have any further questions concerning this subject, 

please contact Laurel Schultz at (919) 541-5511 . 

Attachment 

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ATTACHMENT 

Example of Ozone Contingency Plan Provisions : 

The following provisions might be included in a contingency plan : 

1) Inclusion of several potential scenarios that could 

trigger implementation of the contingency plan - 

A State may choose to establish a number of indicators to 

trigger contingency measures . For example, one scenario for 

ozone may be an increase in volatile organic compounds (VOC) 

emissions which exceeds a predetermined "action line" level 

(encroaching into the emission margin of safety), but does not 

necessarily produce ozone violations . Another situation, 

regardless of the actual VOC emissions, may involve actual 

violations of the national ambient air quality standards (NAAQS) 

for ozone . For CO, the trigger will probably have to be based on 

ambient concentrations, but a specified emission level may be 

used as a supplement in some situations . 

2) Structured levels of measures to be implemented due tothe extent of the problem - 

Once the State has established the indicators and trigger 

levels, it may identify specific measures to correspond to each 

of the triggers . For example, if the first scenario involving 

ozone occurs with no violations, then certain defined measures 

may be taken, such as : (a) requirement for VOC emission offsets 

for new and modified major sources at 1 .1 to 1, as required for 

"marginal" areas under the Clean Air Act ; (b) completion of 

comprehensive VOC emission inventory ; and (c) implementation of 

one or more transportation control measures sufficient to achieve 

at least 0 .5 percent reduction in actual areawide VOC emissions . 

Where violations do occur, additional defined measures may be 

implemented, such as Stage II vapor recovery or enhanced 

inspection/maintenance program . Finally, if the above controls 

still are not successful in curtailing violations of the ozone 

NAAQS, additional measures may be employed (e .g ., requirement 

for VOC emission offsets for new and modified major sources at 

1 .15 to 1, as required for "moderate" areas pursuant to the Act) . 

Even more extreme measures may be implemented, such as requiring 

VOC controls on minor new sources (less than 100 tons) and 

requiring reasonably available control technology on sources 

covered by new Environmental Protection Agency (EPA) control 

techniques guidelines documents . As a last resort, if the above 

measures fail to bring the area back into attainment, the State 

could commit in its contingency plan that it will request 

designation to nonattainment at the appropriate classification . 

This last measure is not essential, as EPA has the authority 

under section 107 to unilaterally redesignate an area . 
3) Detailed description of particular measures to be 

undertaken - 

The State should provide as much detail as possible 

concerning the contingency measures to be implemented . For 

example, if transportation control measures are included, the 

plan should specify the levels to which they will apply . For 

instance, such specifications could include trip reduction 

programs for employers of more than x_ number of employees that 

will mandate a specified vehicle occupancy rate ; transit 

improvements such as purchase of y number of buses to be placed 

on specified routes ; traffic flow improvements (e .g ., no left 

turns at specified blocks) ; alternative fuels programs for fleet 

vehicle operations over a specified size fleet ; vehicle antitampering programs ; and other innovative transportation control 

measures . 

4) Discussion of preparatory actions necessary before actual 

implementation of certain measures - 

The plan should identify the procedure to be used to adopt 

and implement the contingency measures to ensure promptness . For 

instance, before implementation of Stage II vapor recovery, 

affected individuals/industries need proper notification . Local 

and State officials should be well informed of any changes . An 

official notification scheme should be included as part of the 

contingency plan . In addition, the State should submit a 

schedule of when each of these elements of the procedure will be 

completed . The schedule should also account for the time needed 

by the State to adopt specific measures .