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Indicator: Air Quality

Data and Data Discussion provided by Communities Count

Figure 1: Annual Number of Good and Moderate Air Quality Days

Figure 2: Particulate Matter and Ground-level Ozone

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Upstream Indicators
  •   Air Releases of All Reported Toxic Chemicals --- Overall, there has been a substantial decrease in toxic air emissions since the late 1980s in King County, particularly in the South Region. Since 2000 the total toxic emissions have decreased by about half. However, some communities are at greater risk of toxic exposures.  (view data graph)
  •   Urbanization and Impervious Surface Changes --- The number of acres of urban land, clear-cut, and regenerating forest have increased in King County since 1986. Acres of grass and deciduous, mixed and coniferous forest have decreased. Acres of rural forests and privately owned working forests have declined in recent years  (view data graph)
  •   Consumer Environmental Index --- Through their purchasing decisions, Washington consumers have increased their total environmental impacts by 24% since 2000. Even on a per capita basis consumption impacts have gone up 17%.   (view data graph)
  •   Organic Farm Trends --- The number of certified organic farms in King County has more than tripled from 7 in 1995 to 23 in 2002, and remained relatively constant since then. The amount of acreage in organic production increased substantially in 2007.   (view data graph)
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Downstream Indicators
  •   Pollution in Neighborhoods --- It appears that some neighborhoods, particularly those with lower income levels and greater racial diveristy, are more at risk of pollution from Toxic Release Facilities, hazardous waste sites, and other sources.  (view data graph)
  •   Toxics Found in Bodies --- The data we have at this time is a snapshot of the level of some toxins people are carrying around in their bodies. We don’t yet have the research to tell us if these numbers are going up or down or even what the current levels might signify in terms of human health. 
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Related Goals

Transportation sustainability greatly affects air quality. The more we get around by car, the more our air quality suffers.

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Sustainability Snapshot:

Air pollutants such as fine particulates and ozone can cause a range of impacts on human health, from asthma to cancer. People most at risk to low levels of exposure to air pollutants include children, the elderly, people with weakened immune systems, and people with respiratory problems. Poor air quality can also impair scenic visibility, affect vegetation, and cause damage to the built environment.

Sustainability Trend:

The number of good and moderate air quality days has remained steady since 2001. Before then, the number of moderate days declined as good days increased. People most at risk to exposure to pollutants include children, the elderly, people with weakened immune systems and people with respiratory problems. Poor air quality can also impair scenic visibility, affect vegetation and cause damage to the built environment.

Data Discussion

The Indicator Defined

Air quality is measured across the nation using the Air Quality Index (AQI). The AQI measures concentrations of the following six criteria pollutants: carbon monoxide, nitrogen dioxide, sulfur dioxide, ozone and particulate matter. There are four air quality levels that are dependent on concentrations of the pollutants. The levels include: good, moderate, unhealthy for sensitive people and unhealthy. The worst pollutant, or the pollutant with the highest concentration, determines the AQI.

Data Interpretation/Evaluation

Between 2001 and 2007, the combined number of good or moderate air quality days in the year rose from 359 to 62. The number of good days increased to 285 while the number of moderate days decreased to 77 in 2007.

Concentrations of most air pollutants have decreased over the last decade due to better emission controls. A good example is carbon monoxide. According to the Puget Sound Clean Air Agency, carbon monoxide had decreased to zero by 2004 and no longer required monitoring in the region. However, ground-level ozone and fine particulate matter remain a concern in King County.

Data Source and Limitations

The air quality data were contributed by Communities Count (www.communitiescount.org) and originally collected from the Puget Sound Clean Air Agency Air Quality Reports, 2003 as well as personal communications with Kathy Himes and Mary Hoffman from the Puget Sound Clean Air Agency (http://www.pscleanair.org/) and the King County Benchmark Program.

Air quality is defined by the Air Quality Index (AQI), a national standard identified by the United States Environmental Protection Agency. The AQI is reported according to a 500-point scale for each of the major criteria pollutants. Good air quality (0-50) demonstrates that there is little or no risk from pollutants. Moderate air quality (51-100) is denoted when there are health concerns for a small number of people. A more stringent index (101-150) was identified in 1999 and demonstrates when air quality is unhealthy for populations that are sensitive, such as people with health conditions. Unhealthy air quality (151-200) is when the air is considered unhealthy for the entire population.

The federal standard for daily PM2.5 concentrations is currently 65 _g/m3. The Puget Sound Clean Air Agency Board of Directors adopted a more stringent goal based on recommendations of Particulate Matter Health Committee. The Committee conducted a systematic review of health data and determined that a daily average of 25 _g/m3 is protective of human health.

The main limitation with the data is due to the change in the way data were collected for fine particulates in 1999. Due to the stringent standards air quality appears to have declined from 1998 and 1999 though the decline can be attributed to more types of pollutants being measured more frequently.

The Air Quality Index includes data on criteria pollutants, thereby excluding all other types of air pollution such as air toxins and greenhouse gases.

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Additional Resources

  • Air Quality Web Cams
    View the visibility of Seattle's skyline through the Puget Sound Clean Air Agency Visibility Camera.