Air Quality Index ripe for an upgrade: What needs changing and why

This post picks up where the “Why the current Air Quality Index tool should go the way of analog T.V.” post left off. That I feel as I do about this subject matter is justification enough in my mind’s eye to further the discussion.

Just in case you missed it, three people commented to that particular post, all contributing substantive commentary. Each of the comments was responded to by a comment of my own. The opinions shared by Mike McLeod, Mark Simko and Ann are very much appreciated.

But it was Ann’s comment that really got me thinking about this more. Here is what Ann wrote:

“This is ridiculous. Who decides where the division between healthy and unhealthy comes? What we have now lets us think about what our own health is, and what kind of activities we can do without getting into trouble. A small child, an asthmatic, and a healthy 20 year old have different cut-off points for outdoor activities. If the unhealthy cut-off is too low for the latter, they’ll learn to ignore it. If it’s too high for the former, they’ll be doing things which are not safe for them.”

I prefer to look at the situation this way. There are currently six different tiers or states of Air Quality Index categories. They range from Good to Hazardous. At AirNow.gov on the “AQI Basics for Ozone and Particle Pollution” page, in the illustration shown, besides columns for “Daily AQI Color,” “Levels of Concern,” and “Values of Index,” there is another for “Description of Air Quality.” What you will also notice is that air, even in the “Good” range, to some may present a risk, this, of course, being dependent on what the underlying factors or conditions are that would contribute to the susceptibility of vulnerable populations being adversely impacted.

U.S. map showing hourly air-quality updates on Jan. 23, 2009

Keep in mind that within the “Good” range, representative AQI numbers vary between 0 and 50, 0 reflective of, as I understand it, the presence of air pollution that presents the least risk and 50 reflective of pollution in air, that while not presenting as potentially low a risk as air with an AQI of 0, does not have quite the risk potential as air which has an AQI of 51 which, in this case using this specific air-quality-delineating-apparatus, is considered “Moderate.”

As to Ann’s point as to “this” being “ridiculous,” I simply cannot agree.

In looking at my situation as someone who is considered to be at relative higher risk due to my age and physical condition, I would much prefer that if there is going to be an AQI, it be simplified to two tiers only: “Good” (where reflective corresponding AQI numbers could be between 1 and 50) and “Unhealthy” (where reflective lowest corresponding AQI number could be 51).

And here’s why. Say, for example, using the present Air Quality Index tool, forecast for tomorrow is an AQI of 131, which is in the “unhealthy for sensitive individuals” or orange range.

As such, I may choose to plan my day such that I do not venture out of doors and limit physical activity and/or exercise. On the other hand, a member of the general population who is unlikely to be impacted in the same way as me, may, instead, choose to go about business as usual, meaning they might decide to get a fire going in their fireplace, which, in conjunction with a multitude of others doing the same, the reality is such that the probability would be high that in so doing this would serve to make matters worse. Whereas instead, with an Air Quality Index kept to just two tiers – Good and Unhealthy and, say, tomorrow’s forecasted AQI calls for “Unhealthy” air (and, again, this would take into consideration all populations regardless of vulnerability susceptibility), while there is the expectation that not everyone would alter their individual behaviors accordingly taking the quality of air into consideration, a good number of people might adjust their routines enough such that there would be a substantive difference made.

The other thing to remember is that there are the National Ambient Air Quality Standards. The NAAQS for daily ozone (O3) averaged over 8 hours is set at 70 parts per billion parts of air while the NAAQS for fine particulate matter (PM2.5) averaged over 24 hours is set at 35 micrograms per cubic meter of air. As it stands, whether it is 70 parts per billion for ozone or 35 micrograms per cubic meter for fine particulate matter, both correspond to an AQI of 101. At 101 and higher, such standard is exceeded, meaning air is unhealthy, while at 100 and below, air is good.

As for being concise, that right there my friends, is both simple and clear. In other words, it doesn’t get any simpler – and clearer – than this!

AQI colors as depicted in the citrus fruit slices

Images: US EPA and partners (upper), U.S. National Institutes of Health (lower)

– Alan Kandel

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