Question: What is the correct AQI measure ?

sagarpreet is asking a question about air-quality: Subscribe to answer questions on this topic

sagarpreet asked on June 22, 2018 12:44
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I have been working on showing data from PurpleAir Layer onto a map in the form of a HeatMap .

I have the value of PM2.5 , should i convert it to US-Based value AQI ? Will that make more sense ?

My work on it so far : https://github.com/publiclab/leaflet-environmental-layers/issues/14

Heat Map looks like this if i am using PM2.5 Value :

image description

The conversion can be done using this formula :

wiki.png



mapping-meet-up air-quality leaflet dust pm general purpleair soc-2018 aqi

question:air-quality question:pm question:purpleair



7 Comments

This is an awesome post by the way @sagarpreet!!!


Thank you :)


I wonder if @marlokeno, @nanocastro, @imvec, @xose, @zengirl2, @JamesWarren, @the_butler, @guolivar, or @DrJessie may be interested in this post or have some input.

Folks, this is related to @sagarpreet's work to develop a common environmental layers mapping library: https://publiclab.org/notes/sagarpreet/06-06-2018/leaflet-environmental-layer-library -- i'm sure he'd love input!

Also, this looks like an interesting related post! https://publiclab.org/notes/Zengirl2/04-20-2017/epa-s-beta-c-tools-community-tools-for-modeling-near-road-or-port-air-quality


This is interesting. What unit is PM2.5 in? If it's ug/m3 then I think it's best to not change it because ug/m3 is one of the most widespread measures used around the world, I believe.

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Thanks for reply :) Yes the unit is in ug/m3 .


Can someone also help me with this ?

I have 2 options for making heatmap : 1.) Either use global maxima and global minima value (of PM2.5 in ug/m3) to make heat map .

2.) Or to use only the values which are in the current viewport of the map .

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Great work @sagarpreet!

This might get rambly because there is no right answer but I'll try to explain why and what then.

The first thing you need to understand is that all AQ indices are designed for COMMUNICATION purposes so the question is not "should I report concentrations or indices?" but rather "what am I trying to communicate?"

There are many indices and all of them serve different purposes. Some are "regulation" related so they refer to the corresponding regulation limits. These are pollutant dependent so you can have a high index for PM2.5 and a low index for Ozone at the same time which will mean that concentrations of PM2.5 are near or above the standard (whatever that is) while Ozone concentrations are well below the standard.

Now, there is an argument that the standards have very little meaning for the general public as their meaning is unclear and they are defined on many different time bases. So, that's where the "health effect based" indices come in. They try to communicate "risk to people" rather than "state of the air" so a high index value would mean that there is a high risk of a health impact (whatever that may be) with these conditions... that's what the AQI tries to do

In general, if you want people to do somehting, show them something they can understand so AQI's are much more useful for that BUT you need to be VERY careful with the averaging times you're using and you need to be very transparent on where you got the calculations from because if you tell people that their air is OK but it isn't, you're in trouble.

So ... decide what you want to communicate and run with it documenting your sources.

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3 Answers

I used the formula given on the pic above :grinning: . Now the heat map looks like this :

Screen_Shot_2018-06-23_at_12.22.29_PM.png

41806812-2ccc7b16-76e2-11e8-9437-7750252cad36.png


Hi @sagarpreet nice work. I think is better to leave the PM2.5 value because the AQI refers to a combination of pollutants. They https://www.facebook.com/InversionDoc/ are using PurpleAir and show an AQI that is the combination of O3 and PM2.5


Hi @sagarpreet nice work. I think is better to leave the PM2.5 value because the AQI refers to a combination of pollutants. They https://www.facebook.com/InversionDoc/ are using PurpleAir and show an AQI that is the combination of O3 and PM2.5


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Hi @sagarpreet nice work. I think is better to leave the PM2.5 value because the AQI refers to a combination of pollutants. They https://www.facebook.com/InversionDoc/ are using PurpleAir and show an AQI that is the combination of O3 and PM2.5


Yes it makes sense...PM2.5 value seems to be more appropriate . Thank you :)


Hi , I have 2 options for making heatmap :

1.) Either use global maxima and global minima value (of PM2.5 in ug/m3) to make heat map .

2.) Or to use only the values which are in the current viewport of the map .


Which one makes more sense ?

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AQI measures five criteria air toxins (particulate issue, sulfur dioxide, carbon monoxide, nitrogen dioxide, and ozone), and believers the deliberate contamination focuses in a network's air to a number on a size of 0 to 500 my source: Custom Writing Services


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