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occurred on about 2 days out of the year. 



Since almost all of the carbon monoxide emissions comes 

 from motor vehicles, the strategy to reduce carbon monoxide 

 levels centers around reducing emissions from motor vehicles, 

 although controls on stationary sources, e.g., factories, are also 

 part of the strategy. The greatest reduction in motor vehicle 

 emissions will result from newer cars and trucks with more effective 

 emission controls replacing older cars and trucks with less control- 

 led emissions. Although these new, more controlled vehicles will 

 reduce carbon monoxide emissions by over 4 percent between now and 

 1937, this reduction in emissions will not be sufficient to lower 

 the carbon monoxide levels, i.e., ambient concentrations, to below 

 the standard throughout the year. Further measures will be 

 required. Among these measures, inspection/maintenance v/ill pro- 

 vide the most additional reduction in carbon monoxide emissions. 

 Inspection/maintenance should be able to reduce the 1987 carbon 

 monoxide emissions by another 25 percent v/hich should prevent the 

 national carbon monoxide standard from being exceeded. 



