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Reflective Coating on Downtown Parking Lot Helps to Mitigate the Urban Heat Island

The urban heat island (UHI) is the phenomenon of higher nighttime temperatures in the urban core compared to the surrounding rural countryside. The UHI is due to the presence of urban construction materials such as roads, buildings, and parking lots that retain heat absorbed from the sun’s energy during the day and then slowly release that heat to the atmosphere at night. Thus, materials that reflect more sunlight and absorb less heat help to mitigate the urban heat island.  A June 6 article in The Arizona Republic reports that a new city-owned parking lot in downtown Phoenix has been coated with a special material that reflects light and heat.  This coating will help to reduce the surface temperature of the parking lot during the day, allowing the area to cool more quickly at night.  If spread throughout the urban core, small efforts such as this one could help lessen the urban heat island effect in the Phoenix metropolitan area.

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La Niña Conditions Lead to a Dry and Cool Winter, Trapping Dust Pollution

During the winter a brown cloud often hangs over the Valley and, according to a recent article in the Arizona Republic, this winter could be worse than usual. This is a La Niña year, meaning a cool, dry winter in Arizona with no wind and rain to clear the air, creating perfect conditions for trapping winter dust-pollution. Winter pollution is caused by both by fine particles (PM2.5) responsible for haze, and coarse dust (PM10) which accumulates in the upper respiratory tract of humans and is thus thought to contribute to chronic bronchitis, decreased lung function, coughing, painful breathing and premature death. Since 1996, Maricopa County has been classified as a serious PM10 nonattainment area. In 2007, Maricopa County submitted a plan to reduce PM10 pollution by 5% each year. Inability to meet this goal has led to a proposal for new off road vehicle restrictions as a further measure to decrease dust. Failure to reach EPA attainment can lead to the loss of federal transportation funds in addition to increased health threats for the citizens of Maricopa County.

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Hot Overnight Lows Keep Valley Residents From Feeling Relief

The number of days when the temperature does not drop below 90° at night has increased greatly in the last several years. This is an indication of the urban heat island, a phenomenon of higher nighttime temperatures in the urban core compared to the surrounding rural countryside. A September 6 article in The Arizona Republic reported that the overnight low for Phoenix in June, July, and August 2010 averaged 82.8°, almost 3° above normal, and was the fifth-warmest nighttime average in 114 years of record keeping. When temperatures do not drop below 90° at night, nighttime temperatures provide less relief from the summer heat and air conditioners must run almost continually, increasing energy use. The overnight "low" at Sky Harbor Airport only dropped to 94° for three of the nights in July 2010.

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Over One-Third of Energy Produced in Arizona Is From Coal, But Not Without Controversy

Not all electricity that is generated in Arizona is used by Arizonans; much of it is exported to neighboring states, particularly to markets in Southern California. In 2007, over one-third (36.4%) of the energy generated in Arizona was from coal, with much of that produced by the Navajo Generating Station. New rules proposed by the Environmental Protection Agency would force owners of the coal-fired station near Page to install complex new air scrubbers to break down the pollutants that can restrict visibility in the Grand Canyon. Critics fear that the cost of these scrubbers would lead to increases in the price of water supplied by the Central Arizona Project (CAP). Power generated by the Navajo Generating Station is used to pump water from the Colorado River through the (CAP) canal to users in the Phoenix and Tucson metropolitan areas.


Arizona’s Sustainability

The material is highly refined and can fill every pore on the surface it covers. It also is reflective, which is why it can help reduce the surface temperature by 25 to 30 degrees.

Sustainability is often defined as meeting the needs of the present, while not compromising the ability of future generations to meet their own needs. A sustainable society works to balance the needs of the economy, environment, and society. This means considering how our use of land, water, energy, and atmosphere can protect quality of life, livability, and prosperity across all segments of society and for future generations. Increasingly, governments, businesses, and organizations in Arizona and around the globe are putting sustainability into practice as:

  • An overarching value that requires the best practices at every level of organization
  • A framework for building strong economies, healthy environments, and equitable opportunities
  • An organizing principle for local and state governments
  • An area in which every person can make a contribution

Sustainability indicators include metrics associated with air and water quality, energy, urban heat island, and land use.