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Yesterday’s wildfire smoke recap and outlook for today

Yesterday’s wildfire smoke resulted in a 24-hour average, midnight to midnight, of 31.4 micrograms or 92 on the AQI scale.  The federal, health-based standard for fine particles is 35 micrograms per cubic meter of air averaged 24-hours, midnight to midnight (or 100 on the AQI scale).

Below is a graph depicting the hourly levels on Current Air Quality.  The highest hourly update was at 10 pm, with a 164 reading.  

What’s the difference between the Current Air Quality and the daily Air Quality Index?   

  • The daily AQI is used for reporting daily air quality and is based on a daily maximum exposure (8-hour average for ozone and a midnight to midnight 24-hour average for PM.)
  • The purpose of the Current Air Quality is to give people real-time information so they can act to reduce their exposure to high levels of air pollution. This is important when we have temporary spikes in air pollution levels from events like dust storms and wildfire smoke.

  • The main reason we report two values for air quality is because by the time the daily AQI is calculated, it would be too late for people to take actions that reduce their pollution exposure. So, we use short-term data to report Current Air Quality. To do so, we use a national, standardized method (called the NowCast) developed by EPA.

  • The NowCast is EPA’s method for relating short-term (less than 24-hour) data to the Air Quality Index for the purposes of real-time reporting. 


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