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Dissecting ISO 37120: Does your city's air quality measure up to the new smart city standard?

Submitted by scc staff on August 13, 2014

By George Karayannis, LEED AP

Image removed.We continue our series on the new ISO 37120 Smart City standard with a look at the fourth of 17 themes defined in the standard – environment indicators.  As previously described, ISO 37120 includes 46 ‘Core’ (must report) and 54 ‘Supporting’ (should report) indicators.  The environment theme has three Core and five Supporting indicators.

This indicator's primary focus is air quality.  The World Health Organization (WHO) estimates that outdoor air pollution caused 3.7 million premature deaths worldwide in 2012. That’s about the whole population of the city of Los Angeles dying every year from exposure to small particulate matter (PM) of 10 microns or less in diameter. (For comparison, a human hair is about 75 microns wide.) These particulates pass through the throat and nose and enter the lungs, causing cardiovascular disease, respiratory disease and cancers.

“'We change what we measure – and so it's a good thing when cities carefully and persistently measure what's in the air their residents breathe and the water they drink," says Bill McKibben, a noted author, environmentalist and founder of "High standards help keep cities in the forefront of the environmental fight."

Let's take a close look at the environment indicators in the new smart city standard.

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Core Indicators

1.    Fine particulate matter (PM2.5) concentration.

‘Fine particles,’ such as those found in smoke and haze, are smaller than 2.5 micrometers and are emitted from power plants, industrial activity and automobiles.  ISO 37120 conformance requires the use of an air sampler for both particulate matter indicators, with 24-hour readings averaged for yearly values expressed in micrograms per cubic meter (µg/m3).  The WHO’s Air Quality Goals for PM2.5 are 10 µg/m3 as an annual average, and 25 µg/m3 for the 24-hour mean (not to be exceeded for more than three days a year).

2.    Particulate matter (PM10) concentration.

‘Inhalable coarse particles’ are larger than 2.5 micrometers and smaller than 10 micrometers in diameter. The WHO’s Air Quality Goals for PM10 are 20 µg/m3 as an annual average, and 50 µg/m3 for the 24-hour mean.  A WHO European study found that almost 83% of the population across 34 member states was exposed to PM10 levels exceeding targets.  Although this proportion remains high, it is an improvement. Average PM10 levels slowly decreased in most countries in the last decade.

3.    Greenhouse gas emissions measured in tonnes per capita.

Image removed.This indicator measures equivalent carbon dioxide (CO2e) units generated within a city per capita, and refers to the Global Protocol for Community-Scale GHG Emissions for achieving multi-stakeholder consensus for accounting and reporting.  ISO 37120 accommodates inter-city sources of emissions that transcend jurisdictional bodies, and refers cities to the ISO 14064 series on greenhouse gases for additional guidance. (Source for chart)

Supporting Indicators

1.    NO2 (nitrogen dioxide) concentration.

NO2 is a brownish-red gas caused by vehicle emissions and energy production. NO2 reacts in the air to form corrosive nitric acid and falls to earth as acid rain, causing acidification of waterways, damaging trees and accelerating the decay of building materials, metals and other materials.  According to NOAA, emissions controls have successfully decreased NO2 in some areas, while strong economic activity corresponds to increasing NO2 in developing regions. ISO 37120 requires the measuring and reporting of NO2, SO2 and O3 in a fashion similar to PM measurement, with concentrations annualized and reported in µg/m3.

2.    SO2 (sulfur dioxide) concentration.

Sulfur dioxide is an invisible gas with a sharp smell that reacts to form sulfuric acid, which contributes to acid rain.  Whereas NO2 is primarily caused by transportation sources, SO2 is primarily caused by stationary sources such as power plants.  Coal burning is the single largest man-made source of SO2, accounting for about 50% of annual global emissions, with oil burning accounting for a further 25 to 30%.

3.    O3 (ozone) concentration.

Ozone is formed in the troposphere by photochemical reactions in the presence of precursor pollutants such as NOx and volatile organic compounds.  Ozone in the upper atmosphere shields us from high levels of UV radiation. However, at ground-level O3 is harmful to plants, animals and humans. Concentrations are often low in busy urban centers and higher in suburban and adjacent rural areas, particularly on sunny summer days.

4.    Noise pollution.

Noise pollution is excessive noise that contributes to cardiovascular effects, a rise in blood pressure, an increase in stress and vasoconstriction, and an increased incidence of coronary artery disease. ISO 37120 requires the identification of areas where noise levels exceed 55 dB(A), and the calculation of the percentage of city population affected by noise pollution.

5.    Percent change in number of native species.

Urbanization adversely affects biodiversity through urban sprawl, pollution and the introduction of invasive alien species.  Many scientists believe our planet is in the midst of its  sixth wave of mass extinction of plants and animals. Although extinction is a natural phenomenon, it occurs at a natural “background” rate of about one to five species per year. Scientists estimate we’re now losing species at 1,000 times the background rate, with literally dozens going extinct every day.  ISO 37120 requires the reporting of the total net change in species from five taxonomic groups.


George Karayannis has over 25 years of emerging technology and complex solutions sales, business development and marketing experience and has held leadership positions at Schneider Electric, Lockheed Martin Energy Solution, AT&T and wireless sensor startups.  He has also served as a city councilman and is restoring a 100-year old opera house to LEED Gold status. @gkarayannis

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