these pollutants

EPA calls these pollutants "criteria" air pollutants because it regulates them by developing human healthbased and/or environmentally-based criteria (sciencebased guidelines) for setting permissible levels. The set of limits based on human health is called primary standards. Another set of limits intended to prevent environmental and property damage is called secondary standards. A geographic area with air quality that is cleaner than the primary standard is called an "attainment" area; areas that do not meet the primary standard are called "nonattainment" areas.