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Transmission Air Quality

Air Quality
Present, Potentially Affected

In the United States, air quality is regulated by the Environmental Protect Agency (EPA) pursuant to the Clean Air Act (42 U.S.C. §7401 et seq.)

The Clean Air Act requires:

  • The EPA to set National Ambient Air Quality Standards (NAAQS) for pollutants considered harmful to public health and the environment. 42 U.S.C. §7409(a). The EPA has set primary and secondary NAAQS for six principal pollutants, called “criteria” pollutants. These “criteria” pollutants include ozone, particulate matter, carbon monoxide, nitrogen oxides, sulfur dioxide and lead.
  • States to develop State Implementation Plans (SIPs) to attain and maintain the federally established NAAQS. 42 U.S.C. §7410. These plans are developed by state and local air quality management agencies and submitted to EPA for approval.
  • The EPA to regulate emissions of toxic air pollutants from certain industrial sources, referred to as “source categories.” 42 U.S.C. §7412.

The EPA has set National Emission Standards for Hazardous Air Pollutants (NESHAPs) for all major sources of air toxics. 42 U.S.C. §7412. States may set their own toxic air pollutant standards, however they may not fall short of the federal standards. 42 U.S.C. §7412(d)(7).

Air Quality Impacts & Mitigation

Transmission line construction causes minor impacts to air quality. Three impacts include fugitive dust from heavy machinery, and emissions from Volatile Organic Compounds (VOC) or onsite vehicles. The following mitigation measures decrease transmission project impacts to air quality.

Fugitive dust or gravel grinding

  • Develop a Fugitive Dust Abatement Plan
  • Re-grade the dirt surface area and water down transportation areas.
  • Enforce an on-site speed limit, and reduce idle times to maximize equipment usage times.
  • Apply non-toxic soil stabilizers or hydro seed in areas of inactivity (10+ days).
  • Submit a plan for approval to recycle or salvage non-hazardous construction and demolition debris where practicable.
  • Use water sweepers to clean affected streets where soil material is piled.
  • Cease operations when winds cause uncontrollable fugitive dust.

Construction equipment

  • Maintain all construction equipment and vehicles to comply with state and federal standards and reduce idle time to five minutes or less to decrease emissions.
  • Use clean-burning on-road and off-road diesel engines. Vehicles manufactured after 1996 are preferred.
  • During construction, operation, and maintenance, all vehicles will comply with applicable federal and state air quality regulations for tailpipe emissions.
  • Purchase emission credits to offset any emissions levels over the emissions thresholds.
  • Use diesel engines, motors and equipment as far as practicable from residential areas and other sensitive areas (i.e., schools, daycare centers, and hospitals) to mitigate short-term emission impacts.
  • Use the proper size of equipment for the job and use alternative fuels when possible. Examples include: electric vehicles powered by solar, wind, or geothermal power.
  • To avoid plumes, refrain from burning discharge at the construction site.


  • Cover all trucks beds hauling soils or other loose materials, or maintain at least two feet of freeboard (distance between the material and the top of the truck).
  • Consolidate staging areas and carpool during the construction phase to minimize driving distances and the number of cars between staging areas and construction sites.
  • To decrease the delivery truck emissions and driving times, have all materials, including rock for road construction be delivered after peak traffic hours.


  • To mitigate methylene chloride or paint fumes, ventilate the area before painting. Not all paint will pose long-term air quality threats. To best assess the situation, determine the duration, concentration, and chemical structure of the paint before citing it as a major source of air pollution.