Learning Objectives Know the EPA standards for criteria air pollutants. Know the sources, health, and environmental effects of criteria air pollutants. The Clean Air Act, which was last amended in 1990, requires EPA to set National Ambient Air Quality Standards (40 CFR part 50) for pollutants considered harmful to public health and the environment. The Clean Air Act identifies two types of national ambient air quality standards. Primary standards provide public health protection, including protecting the health of "sensitive" populations such as asthmatics, children, and the elderly. Secondary standards provide public welfare protection, including protection against decreased visibility and damage to animals, crops, vegetation, and buildings. The EPA has set National Ambient Air Quality Standards for six principal pollutants, which are called " criteria" air pollutants. Periodically, the standards are reviewed and may be revised. The current standards are listed in Table \(\PageIndex{1}\). Units of measure for the standards are parts per million (ppm) by volume, parts per billion (ppb) by volume, and micrograms per cubic meter of air (µg/m 3 ). Pollutant [links to historical tables of NAAQS reviews] Pollutant [links to historical tables of NAAQS reviews].1 Primary/ Secondary Averaging Time Level Form Carbon Monoxide (CO) Carbon Monoxide (CO) primary 8 hours 9 ppm Not to be exceeded more than once per year Carbon Monoxide (CO) Carbon Monoxide (CO) primary 1 hour 35 ppm Not to be exceeded more than once per year Lead (Pb) Lead (Pb) primary and secondary Rolling 3 month average 0.15 μg/m3 (1) Not to be exceeded Nitrogen Dioxide (NO2) Nitrogen Dioxide (NO2) primary 1 hour 100 ppb 98th percentile of 1-hour daily maximum concentrations, averaged over 3 years Nitrogen Dioxide (NO2) Nitrogen Dioxide (NO2) primary and secondary 1 year 53 ppb (2) Annual Mean Ozone (O3) Ozone (O3) primary and secondary 8 hours 0.070 ppm (3) Annual fourth-highest daily maximum 8-hour concentration, averaged over 3 years Particle Pollution (PM) PM2.5 primary 1 year 12.0 μg/m3 annual mean, averaged over 3 years Particle Pollution (PM) PM2.5 secondary 1 year 15.0 μg/m3 annual mean, averaged over 3 years Particle Pollution (PM) PM2.5 primary and secondary 24 hours 35 μg/m3 98th percentile, averaged over 3 years Particle Pollution (PM) PM10 primary and secondary 24 hours 150 μg/m3 Not to be exceeded more than once per year on average over 3 years Sulfur Dioxide (SO2) Sulfur Dioxide (SO2) primary 1 hour 75 ppb (4) 99th percentile of 1-hour daily maximum concentrations, averaged over 3 years Sulfur Dioxide (SO2) Sulfur Dioxide (SO2) secondary 3 hours 0.5 ppm Not to be exceeded more than once per year (1) In areas designated nonattainment for the Pb standards prior to the promulgation of the current (2008) standards, and for which implementation plans to attain or maintain the current (2008) standards have not been submitted and approved, the previous standards (1.5 µg/m3 as a calendar quarter average) also remain in effect. (2) The level of the annual NO2 standard is 0.053 ppm. It is shown here in terms of ppb for the purposes of clearer comparison to the 1-hour standard level. (3) Final rule signed October 1, 2015, and effective December 28, 2015. The previous (2008) O3 standards additionally remain in effect in some areas. Revocation of the previous (2008) O3 standards and transitioning to the current (2015) standards will be addressed in the implementation rule for the current standards. (4) The previous SO2 standards (0.14 ppm 24-hour and 0.03 ppm annual) will additionally remain in effect in certain areas: (1) any area for which it is not yet 1 year since the effective date of designation under the current (2010) standards, and (2)any area for which an implementation plan providing for attainment of the current (2010) standard has not been submitted and approved and which is designated nonattainment under the previous SO2 standards or is not meeting the requirements of a SIP call under the previous SO2 standards (40 CFR 50.4(3)). A SIP call is an EPA action requiring a state to resubmit all or part of its State Implementation Plan to demonstrate attainment of the required NAAQS. Table \(\PageIndex{2}\) list the sources and harmful effects of criteria pollutants. 0 1 2 3 Pollutant Sources Health Effects Environmental Effects Ground-level Ozone (O3) Secondary pollutant typically formed by chemical reaction of volatile organic compounds (VOCs) and NOx in the presence of sunlight. Decreases lung function and causes respiratory symptoms, such as coughing and shortness of breath; aggravates asthma and other lung diseases leading to increased medication use, hospital admissions, emergency department (ED) visits, and premature mortality. Ozone affects sensitive vegetation and ecosystems, including forests, parks, wildlife refuges and wilderness areas. In particular, ozone harms sensitive vegetation during the growing season. Particulate Matter (PM) Emitted or formed through chemical reactions; fuel combustion (e.g., burning coal, wood, diesel); industrial processes; agriculture (plowing, field burning); and unpaved roads. Short-term exposures can aggravate heart or lung diseases leading to respiratory symptoms, increased medication use, hospital admissions, ED visits, and premature mortality; long-term exposures can lead to the development of heart or lung disease and premature mortality. Visibility impairment Fine particles (PM2.5) are the main cause of reduced visibility (haze) in parts of the United States, including many of our treasured national parks and wilderness areas. Environmental damage Particles can be carried over long distances by wind and then settle on ground or water. Depending on their chemical composition, the effects of this settling may include: · making lakes and streams acidic · changing the nutrient balance in coastal waters and large river basins · depleting the nutrients in soil · damaging sensitive forests and farm crops · affecting the diversity of ecosystems · contributing to acid rain effects. Materials damage PM can stain and damage stone and other materials, including culturally important objects such as statues and monuments. Some of these effects are related to acid rain effects on materials. Lead Smelters (metal refineries) and other metal industries; combustion of leaded gasoline in piston engine aircraft; waste incinerators; and battery manufacturing. Damages the developing nervous system, resulting in IQ loss and impacts on learning, memory, and behavior in children. Cardiovascular and renal effects in adults and early effects related to anemia. Lead is persistent in the environment and can be added to soils and sediments through deposition from sources of lead air pollution. Other sources of lead to ecosystems include direct discharge of waste streams to water bodies and mining. Elevated lead in the environment can result in decreased growth and reproductive rates in plants and animals, and neurological effects in vertebrates. Oxides of Nitrogen (NOx) Fuel combustion (e.g., electric utilities, industrial boilers, and vehicles) and wood burning. Aggravate lung diseases leading to respiratory symptoms, hospital admissions, and ED visits; increased susceptibility to respiratory infection. NO2 and other NOx interact with water, oxygen and other chemicals in the atmosphere to form acid rain. Acid rain harms sensitive ecosystems such as lakes and forests. NOx in the atmosphere contributes to nutrient pollution in coastal waters. Carbon Monoxide (CO) Fuel combustion (especially vehicles), industrial processes, fires, waste combustion, and residential wood burning. Reduces the amount of oxygen reaching the body’s organs and tissues; aggravates heart disease, resulting in chest pain and other symptoms leading to hospital admissions and ED visits. NaN Sulfur Dioxide (SO2) Fuel combustion (especially high-sulfur coal); electric utilities and industrial processes; and natural sources such as volcanoes. Aggravates asthma and increased respiratory symptoms. Contributes to particle formation with associated health effects. At high concentrations, gaseous SOx can harm trees and plants by damaging foliage and decreasing growth. SO2 and other sulfur oxides can contribute to acid rain which can harm sensitive ecosystems. Source: www.epa.gov The likelihood of immediate reactions to air pollutants depends on several factors. Age and preexisting medical conditions are two important influences. Some sensitive individuals appear to be at greater risk for air pollution-related health effects, for example, those with pre-existing heart and lung diseases (e.g., heart failure/ischemic heart disease, asthma, emphysema, and chronic bronchitis), diabetics, older adults, and children. In other cases, whether a person reacts to a pollutant depends on individual sensitivity, which varies tremendously from person to person. Some people can become sensitized to biological pollutants after repeated exposures, and it appears that some people can become sensitized to chemical pollutants as well. Paying the Price Pollution has a cost. Manufacturing activities that cause air pollution impose health and clean-up costs on the whole of society, whereas the neighbors of an individual who chooses to fire-proof his home may benefit from a reduced risk of a fire spreading to their own homes. A manufacturing activity that causes air pollution is an example of a negative externality in production. A negative externality in production occurs “when a firm’s production reduces the well-being of others who are not compensated by the firm." For example, if a laundry firm exists near a polluting steel manufacturing firm, there will be increased costs for the laundry firm because of the dirt and smoke produced by the steel manufacturing firm. If external costs exist, such as those created by pollution, the manufacturer will choose to produce more of the product than would be produced if the manufacturer were required to pay all associated environmental costs. Because responsibility or consequence for self-directed action lies partly outside the self, an element of externalization is involved. If there are external benefits, such as in public safety, less of the good may be produced than would be the case if the producer were to receive payment for the external benefits to others. However, goods and services that involve negative externalities in production, such as those that produce pollution, tend to be over-produced and underpriced since the externality is not being priced into the market. Pollution can also create costs for the firms producing the pollution. Sometimes firms choose, or are forced by regulation, to reduce the amount of pollution that they are producing. The associated costs of doing this are called abatement costs, or marginal abatement costs if measured by each additional unit. In 2005 pollution abatement capital expenditures and operating costs in the US amounted to nearly $27 billion. Summary The EPA has set National Ambient Air Quality Standards for six principal pollutants, which are called " criteria" air pollutants. The six criteria pollutants are carbon monoxide, lead, nitrogen dioxide, ozone, particulate matter, and sulfur dioxide. The key air pollutants can cause various environmental and health problems that could affect the respiratory, nervous, and cardiovascular systems. Contributors and Attributions US EPA Wikipedia Marisa Alviar-Agnew ( Sacramento City College )