Ammonia (NH₃)

Ammonia, according to the EPA, is a common toxicant derived from wastes, fertilizers, and natural processes. Ammonia nitrogen includes both the ionized form (ammonium, NH₄+) and the unionized form (ammonia, NH₃). An increase in pH favors formation of the more toxic unionized form (NH₃), while a decrease favors the ionized (NH₄+) form. Temperature also affects the toxicity of ammonia on aquatic life. Ammonia is a common cause of fish kills, but the most common problems associated with ammonia relate to elevated concentrations affecting fish growth, gill condition and organ weights. Hematocrit exposure duration and frequency strongly influence the severity of effects. Ammonia in sediments typically results from bacterial decomposition of natural and anthropogenic organic matter that accumulates in sediment.

A group of organizations led by the Environmental Integrity Project (EIP) petitioned the EPA recently to regulate ammonia as a criteria pollutant under the Clean Air Act's Sections 108 and 109. The EPA currently regulates airborne ammonia under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), commonly known as the Superfund, and the Emergency Planning and Community Right-to-Know Act (EPCRA) as a hazardous substance. The Agency for Toxic Substances and Disease Registry (ATSDR) characterizes ammonia as a toxin because exposure to airborne ammonia can result in severe respiratory effects.

Whether the EPA chooses to fold ammonia emissions into the Clean Air Act may depend upon the National Air Emission Monitoring Study data processing that is underway at the agency. If EPA were to list ammonia as a criteria pollutant under Section 108, activities under Section 109 would follow. These activities include setting a schedule for development of primary and secondary standards under National Ambient Air Quality Standards (NAAQS) to protect public health and welfare. If an area (often defined as a county) exceeds the NAAQS for a criteria pollutant, the appropriate permitting agency is charged with developing a state implementation plan to bring the area into attainment of the standard.

If the EIP's petition is successful and ammonia is listed as a criteria pollutant, the action has the potential to significantly impact food production. Agriculture (both animal and crop agriculture) is the largest source of ammonia emissions. Development of primary and secondary standards under the Clean Air Act for ammonia could mean that mitigation is required for point sources (like concentrated area feeding operations [CAFOs]) that exceed the standards. This could also mean that some of the CAFOs will require permits under Title V. States with designated authority will oversee the permitting process and enforce standards.

This petition follows a recent EIP report that interpreted findings of an industry-funded EPA study that monitored ammonia, particulates, hydrogen sulfide and volatile organic compounds from CAFOs across the country.

Benzene

A cancer-causing HC (C₆H₆) derived from petroleum. Benzene is a component of gasoline. Benzene emissions occur in exhaust as a byproduct of fuel combustion and also occur when gasoline evaporates.

Carbon Dioxide (CO₂)

This is a colorless, odorless, and tasteless product of combustion. All combustion processes and human metabolic processes are sources of CO₂. Concentrations of CO₂ from people are always present in all occupied buildings, and at concentrations normally found in buildings, CO₂ is not a health hazard.

Carbon Monoxide (CO)

CO is a colorless, odorless gas emitted from the incomplete combustion of HC fuels. Nationally and, particularly in urban areas, the majority of CO emissions to ambient air come from mobile sources. CO can cause harmful health effects by reducing oxygen delivery to the body's organs (like the heart and brain) and tissues. At extremely high levels, CO can cause death. EPA first set air quality standards for CO in 1971. For protection of both public health and welfare, EPA set an eight-hour primary standard at nine parts per million (ppm) and a one-hour primary standard at 35 ppm. In a review of the standards completed in 1985, EPA revoked the secondary standards (for public welfare) due to a lack of evidence of adverse effects on public welfare at or near ambient concentrations. The last review of the CO NAAQS was completed in 1994 and the Agency chose not to revise the standards at that time.

Although you cannot see or smell CO, this poisonous gas is a major air pollutant in many American cities. CO forms when carbon in fuel doesn't burn completely. The main source of CO in our air is vehicle emissions. As much as 95 percent of CO in typical U.S. cities comes from mobile sources, according to EPA studies. Oxidation catalysts are very effective in reducing CO and HC emission levels.

Chlorofluorocarbons (CFCs)

These chemicals and some related chemicals have been used in great quantities in industry, for refrigeration and air conditioning, and in consumer products. CFCs and their relatives, when released into the air, rise into the stratosphere. There, CFCs and their relatives take part in chemical reactions that result in reduction of the stratospheric ozone layer, which protects the Earth's surface from harmful effects of the sun's radiation.

Diesel Particulate Matter

Diesel PM is a component of diesel exhaust (DE). EPA lists DE as a mobile source air toxic due to the cancer and non-cancer health effects associated with exposure to whole DE. Diesel PM (expressed as grams diesel PM/m3) has historically been used as a surrogate measure of exposure for whole DE. Although uncertainty exists as to whether diesel PM is the most appropriate parameter to correlate with human health effects, it is considered a reasonable choice until more definitive information about the mechanisms of toxicity or mode(s) of action of DE becomes available.

Dioxins

These are highly toxic chemicals that can be formed in small amounts from forest fires or volcanoes, but more often are produced unintentionally from industrial activities and from incinerating waste and burning fossil fuels.

Formaldehyde (H₂CO)

Formaldehyde is a colorless water-soluble gas. Due to its wide use, it is frequently considered separately from other VOCs. The EPA has determined that CO can be used as an appropriate surrogate for formaldehyde. Since testing for CO emissions has many advantages over testing for HAPs emissions, most of the emission standards have been finalized using CO as the only regulated pollutant. Sources of formaldehyde in the home include building materials, smoking, household products, and the use of un-vented, fuel-burning appliances, like gas stoves or kerosene space heaters. Formaldehyde, by itself or in combination with other chemicals, serves a number of purposes in manufactured products. For example, it is used to add permanent-press qualities to clothing and draperies, as a component of glues and adhesives, and as a preservative in some paints and coating products.

In homes, the most significant sources of formaldehyde are likely to be pressed wood products made using adhesives that contain urea-formaldehyde (UF) resins. Pressed wood products made for indoor use include: particleboard (used as sub-flooring and shelving and in cabinetry and furniture); hardwood plywood paneling (used for decorative wall covering and used in cabinets and furniture); and medium density fiberboard (used for drawer fronts, cabinets, and furniture tops). Medium density fiberboard contains a higher resin-to-wood ratio than any other UF pressed wood product and is generally recognized as being the highest formaldehyde-emitting pressed wood product.

Other pressed wood products, such as softwood plywood and flake or oriented strand board, are produced for exterior construction use and contain the dark, or red/black-colored phenol-formaldehyde (PF) resin. Although formaldehyde is present in both types of resins, pressed woods that contain PF resin generally emit formaldehyde at considerably lower rates than those containing UF resin.

Hazardous Air Pollutants (HAPs)

The EPA is working to reduce the nearly 200 HAPs pollutants, such as formaldehyde, through its successive NESHAPS regulations, including RICE NESHAP that becomes effective in 2013. Most HAPs originate from human-made sources, including mobile sources (e.g., cars, trucks, buses) and stationary sources (e.g., factories, refineries, power plants), as well as indoor sources (e.g., some building materials and cleaning solvents). Some HAPs are also released from natural sources such as volcanic eruptions and forest fires. Check out Johnson Matthey's total RICE NESHAP solution.

Hydrocarbons (HC)

HC pollution results when unreacted or partially combusted fuel is emitted from the engine as exhaust, and also when fuel evaporates directly into the atmosphere. HCs also react with nitrogen in the presence of sunlight to form ozone. HCs, which may take the form of gases, tiny particles, or droplets, come from a great variety of industrial and natural processes. In typical urban areas, a very significant fraction comes from cars, buses, trucks, and non-road mobile sources such as construction vehicles and boats. Oxidation catalysts are very effective in reducing HC and CO emission levels.

Mercury (Hg)

Mercury is a naturally occurring element found in air, water and soil. (www.epa.gov/mercury/about.htm) Coal-burning power plants are the largest human-caused source of mercury emissions to the air in the U.S., accounting for more than 50 percent of all domestic human-caused mercury emissions, EPA has estimated that about one quarter of U.S. emissions from coal-burning power plants are deposited within the contiguous U.S. and the remainder enters the global cycle. In December 2011 EPA finalized the first-ever national standards to reduce mercury and other toxic air pollution from coal and oil-fired power plants. (www.epa.gov/mats/powerplants.html). More than 20 years after the 1990 Clean Air Act Amendments, some power plants still do not control emissions of toxic pollutants, even though pollution control technology is widely available. Burning hazardous wastes, producing chlorine, breaking mercury products, and spilling mercury, as well as the improper treatment and disposal of products or wastes containing mercury, can also release it into the environment. Current estimates are that less than half of all mercury deposition within the U.S. comes from U.S. sources.

Mercury is an element in the earth's crust. Humans cannot create or destroy mercury. Pure mercury is a liquid metal, sometimes referred to as quicksilver that volatizes readily. It has traditionally been used to make products like thermometers, switches, and some light bulbs. According to the EPA, mercury is found in many rocks including coal. When coal is burned, mercury is released into the environment. In the U.S., mercury compounds are manufactured in small amounts for specialty uses, such as chemical and pharmaceutical applications. Larger quantities of these compounds are generated as byproducts from pollution control activities at gold mines or in waste. Elemental mercury is processed in the U.S. from byproduct mercury compounds, and an unknown quantity of mercury compounds is imported into the U.S. for conversion to elemental mercury.

Mercury in the air eventually settles into water or onto land where it can be washed into water. Once deposited, certain microorganisms can change it into methyl mercury, a highly toxic form that builds up in fish, shellfish and animals that eat fish. Fish and shellfish are the main sources of methyl mercury exposure to humans. Methyl mercury builds up more in some types of fish and shellfish than others. The levels of methyl mercury in fish and shellfish depend on what they eat, how long they live and how high they are in the food chain.

Mercury exposure at high levels can harm the brain, heart, kidneys, lungs, and immune system of people of all ages. Research shows that most people's fish consumption does not cause a health concern. However, it has been demonstrated that high levels of methyl mercury in the bloodstream of unborn babies and young children may harm the developing nervous system, making the child less able to think and learn. Birds and mammals that eat fish are more exposed to mercury than other animals in water ecosystems. Similarly, predators that eat fish-eating animals may be highly exposed. At high levels of exposure, methyl mercury's harmful effects on these animals include death, reduced reproduction, slower growth and development, and abnormal behavior.

Methane (CH₄)

Methane is emitted from a variety of both human-related (anthropogenic) and natural sources. Human-related activities include fossil fuel production, animal husbandry (enteric fermentation in livestock and manure management), rice cultivation, biomass burning, and waste management. These activities release significant quantities of methane into the atmosphere. It is estimated that more than 50 percent of global methane emissions are human-related. Natural sources of methane include wetlands, gas hydrates, permafrost, termites, oceans, freshwater bodies, non-wetland soils, and other sources such as wildfires.

Methane emission levels from a source can vary significantly from one country or region to another, depending on many factors such as climate, industrial and agricultural production characteristics, energy types and usage, and waste management practices. For example, temperature and moisture have a significant effect on the anaerobic digestion process, which is one of the key biological processes that cause methane emissions in both human-related and natural sources. Also, the implementation of technologies to capture and utilize methane from sources such as landfills, coalmines, and manure management systems affects the emission levels from these sources.

Nitrogen Oxides (NO_x)

Many of the nitrogen oxides are colorless and odorless. NO_x is formed with the oxidation of nitrogen in the combustion chamber. The formation of NO_x is favored by high temperatures and excess oxygen (more than is needed to burn the fuel). The primary sources of NO_x are motor vehicles, electric utilities, and other industrial, commercial, and residential sources that burn fuels. NO_x can only be reduced; it cannot be oxidized by a catalyst. Selective Catalytic Reduction (SCR) is the most effective technology for dealing with it.

The common pollutant, NO₂, can often be seen combined with particles in the air as a reddish-brown layer over many urban areas. NO₂ is one of a group of highly reactive gasses known as "oxides of nitrogen," or "nitrogen oxides (NO_x)." Other nitrogen oxides include nitrous acid and nitric acid. While EPA's National Ambient Air Quality Standard covers the entire group of NO_x, NO₂ is the component of greatest interest and the indicator for the larger group of nitrogen oxides. NO₂ forms quickly from emissions from cars, trucks and buses, power plants, and off-road equipment. In addition to contributing to the formation of ground-level ozone, and fine particle pollution, NO₂ is linked with a number of adverse effects on the respiratory system.

EPA first set standards for NO₂ in 1971, setting both a primary standard (to protect health) and a secondary standard (to protect the public welfare) at 0.053 parts per million (53 ppb), averaged annually. EPA has reviewed the standards twice since that time, but chose not to revise the standards at the conclusion of each review. All areas in the U.S. meet the current (1971) NO₂ standards.

Ozone

Ozone can exist either high in the atmosphere, where it shields the Earth against harmful ultraviolet rays from the sun, or close to the ground, where it is the main component of smog. Ground-level ozone is a product of reactions involving HC and NO_x in the presence of sunlight.

Particulate Matter (PM)

Particulate Matter, which is getting increasing regulatory attention, comprises tiny particles or liquid droplets suspended in the air that can contain a variety of chemical components. Larger particles are visible as smoke or dust and settle out relatively rapidly. The tiniest particles can be suspended in the air for long periods of time and are the most harmful. Some particles are directly emitted into the air. They come from a variety of sources such as cars, trucks, buses, factories, construction sites, tilled fields, unpaved roads, stone crushing, and wood burning.

Other particles are formed in the atmosphere by chemical reactions. Diesel-powered vehicles and engines contribute more than half the mobile source particulate emissions. Fine PM is a health concern because very fine particles can reach the deepest regions of the lungs. Health effects include asthma, difficult or painful breathing, and chronic bronchitis, especially in children and the elderly. Fine PM associated with diesel exhaust is also thought to cause lung cancer and is therefore listed as a mobile source air toxic. Fine PM can travel long distances on air currents and is also a major cause of haze, which reduces visibility, affecting cities and scenic areas.

Smog

A mixture of pollutants, principally ground-level ozone, produced by chemical reactions in the air involving smog-forming chemicals. A major portion of smog-formers, VOCs, are found in products such as paints and solvents. Smog can harm health, damage the environment and cause poor visibility. Major smog occurrences are often linked to heavy motor vehicle traffic, sunshine, high temperatures and clam winds or temperature inversion. Smog is often worse away from the source of the smog-forming chemicals, since the chemical reactions that result in smog occur in the sky while the reacting chemicals are being blown away from their sources by winds.

Volatile Organic Compounds (VOCs)

Many of the organic chemicals we use do not occur in nature, but are synthesized in laboratories. Volatile chemicals produce vapors readily; at room temperature and normal atmospheric pressure, vapors escape easily from volatile liquid chemicals. VOCs include gasoline, industrial chemicals such as benzene, solvents such as toluene and xylene, and tetrachloroethylene (perchloroethylene, the principal dry cleaning solvent). Many VOCs are also HAPs; for example, benzene, which causes cancer. VOCs are emitted as gases from certain solids or liquids. VOCs include a variety of chemicals, some of which may have short and long-term adverse health effects. Concentrations of many VOCs are consistently higher indoors (up to 10 times higher) than outdoors. VOCs are emitted by a wide array of products numbering in the thousands. Examples include: paints and lacquers, paint strippers, cleaning supplies, pesticides, building materials and furnishings, office equipment such as copiers and printers, correction fluids and carbonless copy paper, graphics and craft materials including glues and adhesives, permanent markers, and photographic solutions.

Organic chemicals are widely used as ingredients in household products. Paints, varnishes, and wax all contain organic solvents, as do many cleaning, disinfecting, cosmetic, degreasing, and hobby products. Fuels are made up of organic chemicals. All of these products can release organic compounds while you are using them, and, to some degree, when they are stored.

In the U.S., emissions of VOCs to the outdoors are regulated by EPA mostly to prevent the formation of ozone, a constituent of photochemical smog. Many VOCs form ground-level ozone by "reacting" with sources of oxygen molecules such as CO and NO_x) in the atmosphere in the presence of sunlight. However, only some VOCs are considered "reactive" enough to be of concern.

VOCs that are non-reactive or of negligible reactivity to form ozone under these conditions are exempted from the definition of VOCs used by EPA in its regulation. Since first establishing the list of exempt compounds in 1977, the EPA has added several to the list, and frequently has several petitions for additional compounds undergoing review. In addition, some states have their own definitions and lists of exempted compounds. Thus, for regulatory purposes, the specific definition of VOCs outdoors can change by what is excluded from that definition.

EPA formerly defined the regulated organic compounds in outdoor air as "Reactive Organic Gases" (ROG). This terminology clarified its meaning as being limited to reactive chemicals. However, EPA later changed that terminology to "VOC". Unfortunately, the use of the term "VOC" rather than ROG has created a misunderstanding when applied to indoor air quality. Many individuals and organizations, including manufacturers of building materials and products, and third party certification organizations have come to think of VOCs as "only those regulated by EPA for outdoor air", and apply the same definition for indoor air purposes.

To the extent that some exempted compounds impact the health of exposed individuals indoors, the definition of VOCs regulated for outdoor air has the potential to create serious misconceptions for indoor air quality, therefore, such VOCs should not be excluded from consideration for indoor air. For example, methylene chloride (paint stripper), and perchloroethylene (dry cleaning fluid), are exempted compounds for outdoor regulation, but they could pose serious health risks to exposed individuals if present indoors.

Outdoors, VOCs are volatized or released into the air mostly during manufacture or use of everyday products and materials, while indoors VOCs are mostly released into the air from the use of products and materials containing VOCs. VOCs are of concern as both indoor air pollutants and as outdoor air pollutants. However, the emphasis of that concern outdoors is different from indoors. The main concern indoors is the potential for VOCs to adversely impact the health of people that are exposed. While VOCs can also be a health concern outdoors, EPA regulates VOCs outdoors mainly because of their ability to create photochemical smog under certain conditions. Although the same term "VOC" is used for both indoor and outdoor air quality, the term is defined differently to reflect its predominant concern in each context.

This has created a misunderstanding in the marketplace and in the environmental community. In addition, the measured quantity and composition of VOCs in the air can vary significantly depending on the measurement methods used, which has generated additional confusion. Reducing the concentration of VOCs indoors and outdoors is an important health and environmental goal. However, it is important to understand that there are VOCs of concern indoors and outdoors that do not impact photochemical oxidation and are not regulated by EPA (42 U.S.C. §7401 et seq. {1970}).