Final answer:
Air quality is indicated by the Air Quality Index (AQI), which measures levels of pollutants in the air and their effects on human health, specifically focusing on ozone and particulates.
Step-by-step explanation:
Air quality is indicated by the Air Quality Index (AQI), which is an assessment of the levels of pollutants in the outdoor air based on their human health effects. The EPA has set National Ambient Air Quality Standards for six principal pollutants, known as "criteria" air pollutants. These include carbon monoxide, nitrogen dioxide, ozone, particulate matter, sulfur dioxide, and lead. The AQI focuses on the levels of ground-level ozone and particulates, with ozone forming close to the ground when pollutants are heated by sunlight, and particulates being tiny particles of solids or liquids suspended in the air. Both ozone and particulates can cause various environmental and health problems, affecting the respiratory, nervous, and cardiovascular systems.
The other options provided, such as a Carbon report or Carbon footprint, are measures related to greenhouse gas emissions and the overall environmental impact of an individual or organization, but they are not specific indicators of air quality. The EPA is the agency that establishes and enforces air quality standards, but it is not an indicator by itself.