MAC-EQS: 'na' (Not Applicable)

When the MAC-EQS is listed as 'na' (not applicable), it means the regulatory assessment concluded that the annual average standard (AA-EQS) alone provides sufficient protection for both chronic and acute exposure. No separate acute maximum is needed. This is distinct from 'nd' (not derived), which means data was lacking to set a value. The 'na' designation reflects a scientific judgement about the substance's toxicological profile.