Summary
San Francisco tends to occasionally get really bad air quality due to nearby wildfires. This market is intended to capture and predict if/when this will happen in 2024, with an AQI of "Unhealthy for Sensitive Groups" or worse being considered "bad".
Fine print
The source of resolution data is the Bay Area Air Quality Management District website, specifically the row for "San Francisco - Arkansas St." in their monthly AQI highs page which shows the maximum AQI recorded in any given month at that site.
If the high for any given month is within the "Unhealthy for Sensitive Groups" range or higher (101 or more), that month immediately resolves to "Yes". If the end of the month comes without any AQI measurements that high, it resolves to "No".
Note that this page has an "hourly" view which can sometimes show values that are higher than the reported summary high value seen in the "Daily", "Weekly", and "Monthly" views. For simplicity, this market will not look into the "Hourly" breakdowns of each day, relying solely on the summary high values.
Two updates to this market.
First, October resolves NO, with an AQI high of 79.
Second, the EPA has updated some of the thresholds for PM2.5 pollution, lowering the threshold at which “Good” becomes “Moderate”, “Unhealthy” becomes “Very Unhealthy”, and “Very Unhealthy” becomes “Hazardous”. Luckily, the threshold between “Moderate” and “Unhealthy for Sensitive Groups” remains unchanged, so this market’s resolution criteria are also unaffected.