Why is the point gray? And other fun facts about the smoke map!

The fire and smoke map at the top of this page is a great tool for checking current air quality conditions. Clicking on a site gives you information about current conditions, short-term PM2.5 trends, and site monitoring information. You can also see active fire sites and smoke plumes. Here are some frequently asked questions about the map; Let us know if we missed anything in the comments!

What do the different signs on the map indicate?

Circles are permanent displays, operated by state, local, and tribal air quality professionals. The triangles are makeshift displays, and the squares are Purple Air’s low-cost, privately owned sensors, with the EPA corrected equation applied.

Why is the dot on my local air monitor gray?

There are several different reasons why your local air quality monitor is grayed out:

  • We have lost contact with the monitor and cannot receive data
  • There is not enough data to calculate the AQI value (because of the loss of previous connections)
  • Air monitoring operator performs QC or maintenance calibration or inspection
  • Quality assurance personnel perform an audit of instrument performance

Clicking on a site gives me information about the NowCast AQI. What is NowCast?

The points on the map are what the EPA refers to as a “NowCast,” which links current and past hourly PM2.5 concentrations to the air quality index, resulting in the color scale you see on the map. NowCast aims to give you an idea of ​​the precautions you should take Currently, not only based on the last reading, but also on what the trends are. NowCast uses longer averages during times when air quality is stable and shorter averages when air quality is changing rapidly. Therefore, if a new fire starts and air quality rapidly deteriorates, NowCast will show a higher advisory level than the last reading indicates (and vice versa when air quality improves).

You may also notice that the hourly concentrations in the Recent History tab are different from the NowCast AQI – again, this is because of how the NowCast is calculated using several hours of data.

Why is the purple air sensor closest to me different from the nearest regulatory monitor?

Low-cost sensors are great tools for assessing local air quality conditions. Differences in terrain and meteorological conditions between regulatory monitors and low-cost sensors can lead to differences. Regulatory air monitors also follow detailed rules for where they are placed, their distance from local sources, and their inlet height.

Why is Smoke Blog different from other maps?

Many companies and applications refer to AQI values ​​and air quality, but in many cases it is not known how AQI values ​​are calculated or the data used. It is a best practice to seek public agency sources for reliable air quality information.

Some other fun Monday morning facts:

To get the truth about your fun air quality devices today, the figure below shows what it looks like when a spider crawls into a nephelometer, which is used to measure PM2.5 concentrations.

Yes, spiders are everywhere, including our air quality monitors!

And for the folks out there, if it seems like an early start to the fire season in the central and eastern regions of the state, you’re not wrong! Mentioned by Rannell in a previous post, the regional and county breakdown of the number of days spent in each AQI category since 2011 (including summer-only data to today’s date) says the same:

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