| United States Effective monitoring, enforcement, evaluation and communication

Chapter 4 | United States 125

Chapter 4

United States Hi g h l i g h t s  Efforts by the United States to control energy-related air pollution date back to the 1960s. They have produced significant results. Despite continued growth in population, GDP and energy consumption, aggregate emissions of six common air pollutants declined by almost 70 between 1970 and today. On a national basis, average air pollution concentrations have also declined and for all six pollutants are now below national limits. Even so, air quality continues to pose serious local challenges, with over 40 of the US population living in areas that do not comply with at least one of the national standards.  The combined effects of clean air regulations, and energy and climate policies will help further to improve the outlook for air quality: in the New Policies Scenario, SO 2 and NO X emissions each fall by more than 50 by 2040, relative to today, while PM 2.5 emissions drop by one-third. The reductions stem from a range of measures, but strengthening emissions standards in transport and reducing emissions in the power sector with lower emitting technologies are central.  Additional measures in the Clean Air Scenario can further improve the outlook for air quality in the United States: SO 2 emissions fall by an additional 50 by 2040, relative to the New Policies Scenario, NO X by around 40 and PM 2.5 by about 15. These improvements deliver important co-benefits: the fossil-fuel import bill falls as oil demand drops by 1.9 mbd in 2040 relative to the New Policies Scenario, natural gas demand by around 50 bcm and coal demand by 255 Mtce. CO 2 emissions are around 1.1 Gt lower than in the New Policies Scenario, helping to achieve climate change targets. The energy and air quality context The United States has a long history of addressing air pollution and has made great strides in improving air quality since the federal government first began controlling air pollution in the 1960s. The overarching regulatory framework for addressing air pollution is the Clean Air Act, introduced in its modern form in 1970 and amended significantly in 1977 and 1990. It embodies a co-operative approach between the federal government and the states. It has three main components: ambient air quality standards, emissions standards and permitting requirements. The cornerstone is the set of National Ambient Air Quality Standards NAAQS set by the US Environmental Protection Agency US EPA for six common air pollutants: carbon monoxide CO, lead, nitrogen dioxide NO 2 , sulfur dioxide © OECDIEA, 2016 126 World Energy Outlook 2016 | Special Report SO 2 , ozone and particulate matter PM with PM 10 and PM 2.5 regulated separately 1 . Two standards are defined for each pollutant: a primary standard to protect human health and a secondary standard to protect non-health related public welfare such as visibility and damage to crops and buildings. These standards define maximum pollutant concentration levels averaged over a specified period and have been revised over the years Table 4.1. The Clean Air Act requires that individual states develop a plan, subject to US EPA approval, to attain and maintain the NAAQS for all control regions within their jurisdiction. Control regions that the U“ EPA deter i es are i iolatio of NAAQ“ are desig ated as o - attai e t areas a d e o e subject to controls that are more stringent. For each non- attainment area, states must submit specific plans to reach attainment within a set timeframe. States that fail to submit a plan, or submit plans that are found to be inadequate in terms of implementation or enforcement, may be subject to sanctions such as withholding of federal highway funding. Table 4.1 ⊳ National ambient air quality standards in the United States for selected pollutants Pollutant Primary Secondary Averaging time Level Form Last revised NO 2 Primary 1 hour 100 ppb 98th percentile of 1-hour daily maximum concentrations, averaged over 3 years 2010 Both 1 year 53 ppb Annual mean 1971 Ozone O 3 Both 8 hours 0.070 ppm Annual 4th-highest daily maximum 8-hour concentration, averaged over 3 years 2015 PM PM 2.5 Primary 1 year . μg 3 Annual mean, averaged over 3 years 2012 Secondary 1 year 5. μg 3 Annual mean, averaged over 3 years 1997 Both 24 hours 5 μg 3 98th percentile, averaged over 3 years 2006 PM 10 Both 24 hours 5 μg 3 Not to be exceeded more than once per year on average over 3 years 1987 SO 2 Primary 1 hour 75 ppb 99th percentile of 1-hour daily maximum concentrations, averaged over 3 years 2010 Secondary 3 hours 0.5 ppm Not to be exceeded more than once per year 1971 Notes: ppb = parts per billion; ppm = parts per million; μg 3 = microgrammes per cubic metre. Source: www.epa.govcriteria-air-pollutantsnaaqs-table. 1 Size is an important factor in determining the health impacts of PM: oarse parti les are et ee 2.5 and 10 i ro etres µ i dia eter a d fi e parti les are s aller tha .5 µm. © OECDIEA, 2016 Chapter 4 | United States