EPA's AirNow mobile app provides a simple interface for quickly checking current and forecast air quality information for planning daily activities and protecting your health.

Fair The air quality is generally acceptable for most individuals. However, sensitive groups may experience minor to moderate symptoms from long-term exposure.

The marine layer, or the fog and low clouds, are cool and more dense so they can't "float" up and into the atmosphere and therefore hovers near the ground for a long time. They are "capped" or "trapped" by the warm air directly above, and that's why the low clouds can't escape or evaporate, and we have low visibility.