High winds across northern and eastern Arizona prompted dust and air pollution warnings yesterday and today. In addition to the possible health concerns from high dust levels, they can also trigger federal regulations and cost Arizona federal highway funds. [right, windborne dust plumes in northeast Arizona from MODIS satellite. Credit, NASA]
I was in a conference on Friday where AZ Dept. of Environmental Quality Henry Darwin talked about EPA Clean Air rules. If I understood it all, Maricopa County is in nonattainment and is engaged in a developing "5% plan" where dust is being reduced 5% per year until the area is in compliance.
Rather than tracking average air quality, exceeding the national standards more than 3 times in 3 years at any single air quality monitor is a violation. However, 'exceptional' events triggered by natural causes such as high winds, are not counted as violations.
Rejection of the plan by EPA could lead to loss of federal highway funds.
Henry and other members on the conference panel called the EPA "exceptional event" a terrible rule and said EPA agrees but is bound by Congressional mandates.
The major sources of dust are from traffic on unpaved roads and windblown dust from undeveloped lands. Other sources are each minor compared to these.
The TriValley Central paper recently listed complaints filed by citizens in 2010 with authorities in Pinal County over dust sources. You can see the challenges in controlling dust from possibly thousands of sites.