Poor air quality is associated with increased risk of asthma, lung disease, and heart disease. Ground-level ozone, commonly known as smog, and particle pollution pose the greatest known health risks to humans. Air pollutants can also cause damage to lake ecosystems, crops, and our climate. The Air Quality Index, or AQI measures five of the main pollutants regulated by the 1990 Clean Air Act. Days are rated as "Good," "Moderate," "Unhealthy for Sensitive Groups," or "Unhealthy" based upon the amount of pollutants in the air. We can increase the number of Good days that we have by reducing our energy consumption, amount of driving, and waste production.