And even once air quality reaches unhealthy, higher levels can dictate different actions. The higher colors were decided by the AQI Team to show that as air quality worsens, it can be unhealthy for some people before it's unhealthy for everyone. We are not sure anyone knows for certain how the final decision was made, but in the end, DC decided to go with red at the Unhealthy category. In those days, it wasn't unusual to have 30 days when ozone was above the level of the standard. We were also concerned about message fatigue. EPA and many of the state, local and tribal representatives wanted red in the Unhealthy category, because that's when the AQI indicates that air quality can pose a risk to everyone. The environmental groups wanted red in the Unhealthy for Sensitive Groups (USG) category to show that levels were higher than the levels of the NAAQS. Even though we didn't have many continuous PM monitors then, we looked back at the filter-based PM data to evaluate the number of days in different categories. We mostly hit very unhealthy levels with ozone. Those were the days before the huge wildfires out West, so it was extremely rare to get into the Hazardous range. The focus was entirely around the level of the standard and the color red. At a large meeting in Baltimore (in either 1997 or 1998), we took an unscheduled break during the discussion of colors because we thought attendees were going to start pushing and shoving each other. In developing the AQI that we have today, the most heated discussions were about colors.
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