Scales of Green

EPA’s Air Quality Index (AQI)

Dec 05

Posted: under Green Places.


After four posts about scales measuring the environmental performance of automobiles, auto companies, city transportation policies, and even our personal driving skills, we might think that if we do well on each of these measures, our environment should be doing okay.  But how would we know?  We also need measures of environmental quality — the current state of our environment — to assess whether our actions are making a difference; indeed, these are the “Scales of Green” that ultimately matter the most.

One measure that may be a good start is the Air Quality Index (AQI), which the federal government requires all metropolitan areas with populations greater than 350,000 to calculate and distribute to local media outlets.  The scale is from 0 to 500, with five levels and colors of increasing health concern, and highlights pollutant levels that may be particularly hazardous for at-risk groups (e.g. people with heart conditions, asthma, etc.).

Transparency: Air*

EPA’s website provides in-depth descriptions of the AQI and how it is calculated.  A particularly detailed document oriented towards state and local air quality monitoring agencies provides the methods, equations, and tables that should be used to generate the AQI.  The site discusses both what is measured and is not measured, and the limitations of the metric.

Governance: Republic

The AQI is calculated by government agencies based on data from approved air monitoring stations across the country. The EPA provides overall guidance and regulation of the process, while state and local agencies implement it.

Coverage: Hedgehog

While Air Quality Indexes can be calculated for as many as five air pollutants, it does not cover any of the 188 air toxics covered by the Clean Air Act nor any water and ground pollutants.  And often only ozone and particulate matter AQIs are calculated and distributed (if the others are generally shown to be below 50).  Therefore it is a relatively narrow measure of environmental performance, but it is also one of the most precise environmental quality measures available.

This Scale’s “Greenness:”

According to the EPA’s AirNow site, the AQI “tells you how clean or polluted your air is, and what associated health effects might be a concern for you.”  But let’s remember a few important points about this scale:

1. The AQI measures concentrations of five primary pollutants, not toxic pollutants that are more likely to result in longer-term, chronic health outcomes like cancer. An EPA study showed that in some areas these chronic risks may indeed be significant (click here for more info).

2. The AQI focuses on hourly and daily pollutant levels, not long-term trends. The EPA’s National Ambient Air Quality Standards (NAAQS) are more relevant to evaluating our national air quality progress, and EPA’s most recent Trends Report shows that while air quality for the five primary pollutants discussed above has improved over the last 30 years, there are still 158.5 million Americans (more than half) who live in counties with air quality concentrations above the NAAQS.

3. The AQI is focused on human health effects of the air pollutants it measures, not their effects on visibility, either locally or in National Parks, or their effects on vegegation, crops, buildings, and wildlife. Such effects can be significant — see this site on crop damage from ozone as an example.  So while a low AQI may be good for your personal health, it may not necessarily mean the environment is not still being affected.

* For an explanation of the Transparency, Governance, and Coverage “ratings” above, please click here.

Comments (328)

GreenMeter I-Phone Application

Dec 03

Posted: under Green People.


You might own a car with great gas mileage and live in a super-sustainable city, but you still may not be getting around as sustainably as you could.  That’s because, in addition to your car’s fuel economy and your city’s road congestion, your own driving style can significantly impact the fuel mileage you actually get when you’re driving.  Lots of accelerating and braking wastes a lot of gas, by as much as 47% — check out these tips for more info on greener driving (  To help people drive more “greenly,” Hunter Research and Technology has released a “GreenMeter” that uses the I-Phone’s “internal accelerometer to measure forward acceleration and compute engine power, fuel economy, fuel cost, carbon footprint, and oil (barrels) consumption.” Drivers can monitor their acceleration and other indicators to improve their own personal fuel economy, regardless of what kind of car they ride in.

Transparency: *Brick

While the site describes how to setup and calibrate the application and users enter their own basic data (e.g. fuel prices, engine efficiency), very little if any information is provided as to how exactly the numbers are generated.  Without this information, the validity of the absolute numbers is questionable, although as measures of relative performance they may be useful (if they appear to generally respond the car’s acceleration, braking, etc.).

Governance: Monarchy (with Democratic Elements)

The application appears to be developed by a single individual, engineer and company owner Craig Hunter.  Some data must be entered by users, adding a democratic dynamic to the application, which allows for limited control over the application as well as creates the possibility of user-generated errors.

Coverage: Hedgehog

While relatively comprehensive in its coverage of fuel mileage factors, the application nevertheless has a narrow focus on only one environmental impact of automobiles — fuel use.  And from the perspective of the user, it does not assess other impacts of an individual’s lifestyle, such as use of public transportation, biking, etc.

This Scale’s “Greenness:”

The GreenMeter site claims it can “help evaluate your driving style to increase efficiency, reduce fuel consumption and cost, and lower your environmental impact.”  While all of this is true, it is important to remember:

1. The output data on fuel economy is highly questionable as accurate absolute measures of personal environmental impacts (e.g. carbon footprint) due to the lack of transparency into the methods behind the calculations.

2. The GreenMeter may nevertheless function well as a measurement of relative environmental performance over time, and may indeed help drivers reduce their environmental performance.

3. Driving efficiently is not the same as traveling sustainably – total miles driven, total miles travelled using alternative modes of transportation and total greenhouse gases emitted are still the most important measures of environmental performance.

* For an explanation of the Transparency, Governance, and Coverage “ratings” above, please click here.

Comments (298)

SustainLane’s Sustainable Cities

Dec 02

Posted: under Green Governments.


The environmental impact of transporting yourself around does not just depend on what car you drive, but also on what city you live in.  Cities that have affordable and convenient public transportation systems, for example, make it much easier for its citizens to drive and pollute less, regardless of whether they drive an hybrid or a Hummer.  Recognizing the relevance of municipal policies to the environment, SustainLane has published sustainability rankings of the 50 largest US cities over the last three years that cover not only transportation policies but also air quality, green building, and more. The results?  Portland, Oregon won the top spot in 2008, while Mesa, Arizona was in the cellar.

Transparency: *Plastic

The rankings are published on a well-designed website that displays both the overall ratings and the sub-scores that underlie them.  While it includes a general discussion of its methodology and sources,  some of its sources are private and not available to the public.  It is also not clear how the ratings are ultimately calculated, and they are therefore not reproduceable. SustainLane does provide useful bios of the people behind the rating, and engaging graphics illustrating the multiple dimensions of the ratings.

Governance: Oligarchy (with Republican Elements)

The rankings are published by SustainLane, a for-profit media company focused on delivering information to consumers about sustainable living.  The research team is directed by Kenneth Ott, and includes nine researchers, writers, and graphic designers.  The underlying data, however, often comes from government agencies and non-profit organizations.

Coverage: Fox

The issues covered by SustainLane are indeed extensive — air pollution, commuting, green building, energy and climate change, a green economy, housing and affordability, knowledge and communications, water quality, and more (a total of 16 sub-scores).  The comprehensiveness of each sub-score varies, and in many cases the scores appear to be quite robust, but without more information about how the ratings are actually calculated, it is not possible to know for sure.

This Scale’s “Greenness:”

The SustainLane rankings states that it “is the nation’s most complete report card on urban sustainability.”  But how complete, and how green?

1. The scores are indeed quite comprehensive, and appear to be more so than other similar rankings, such as those by Popular Science and Country Home.

2. The rankings are not, however, the most “extensive,” in that they only rate the 50 most populous cities — Country Home, for example, covers 379.  Such a focus on large cities lends the impression that only large cities are sustainable, and undervalues the efforts made by medium-sized and smaller communities.

2. The sub-scores weightings are explained but not fully justified — why are 11 of the 16 equally weighted, while five are adjusted?  Including multiple criteria related on transportation policies rewards cities that have focused on those policies more than others.

* For an explanation of the Transparency, Governance, and Coverage “ratings” above, please click here.

Comments (452)