Mold Pollution

Mold Pollution

Mold pollution is the growth of molds in a building resulting in damage to or the destruction of the structure itself (or its contents) and adverse health effects on the building’s occupants. It is estimated that about 10 percent of U.S. buildings may suffer from mold pollution.

Molds, also known as fungi, are microorganisms that generally have threadlike bodies called mycelium and reproduce by producing spores. Spores are generally round or ovoid single cells (but in some cases are multicellular). Spores can be colorless or pigmented and vary in size. While a human hair is approximately one hundred microns in diameter, spore size ranges from one to five microns.

There are about fifty to one hundred different molds typically found growing indoors in water-damaged buildings. Water problems in buildings are generally the result of leaks from roofs or plumbing, condensation, and flooding. When building materials or furnishings such as wood, drywall, ceiling tiles, or carpets become wet, causing molds to grow on them.


The types of substrates and the amount of moisture will often determine the kinds of molds that grow. For example, some molds like Stachybotrys require a highly water-saturated substrate. For other molds such as Aspergillus, only small amounts of excess moisture are necessary for growth. Thus, moisture control is key to controlling mold growth and eliminating their effects on the building or its occupants.

Mold growth can cause structural integrity problems in buildings constructed of wood. This generally goes under the misnomer of dry rot. The dry rot molds, like Merulis lacrymans, are the natural decomposers of leaves, stems, and trees in nature. If structural wood in buildings becomes wet, these molds may grow. The name dry rot comes from the powdery residue that is left after the wood is destroyed. Wood can be protected by the use of chemicals like creosote or by the use of sealants.

Mold pollution in buildings may result in adverse health effects including infections, allergies, and asthma. Bleeding, memory loss, and a condition known as sick building syndrome may also result from mold pollution, but such health effects remain controversial. Epidemiological studies have linked molds to these conditions; however, a direct causal relationship has not been established.

Green mold

When health effects from molds occur, it is generally as a result of inhaling mold spores. For example, aspergillosis is an infection of the lungs caused by some species of Aspergillus, which can result in difficulty breathing. If left untreated, it can spread through the bloodstream to other organs, resulting in death. It is probably the most common type of building-acquired infection.

Individuals with impaired immune systems are most susceptible to this infection. Mold infections can be acquired in health care facilities (nosocomial infections). Careful attention to removing spores from the air and water may be the best method to protect the public from these kinds of infections.

Occasionally, mold infections result from animals and birds inhabiting buildings. For example, bats or pigeons may deposit guano containing such molds as Histoplasma capsulatum and Cryptococcus neoformans. Disturbing this guano without respiratory protection can result in infection. The best defense against this kind of mold pollution is to keep these creatures out of the building.


In addition to infections, allergic diseases are associated with mold pollution. Asthma is the most common chronic disease of childhood and is the leading causes of school absenteeism, accounting for over ten million missed school days per year.

For most elementary school children with asthma, allergens are the primary trigger for asthma, and their disease is thought to result from early exposure and sensitization to common allergens in their environment (e.g., dust mites, cockroaches, and molds). To prevent allergic disease, excessive mold growth must be controlled or eliminated.

The elimination of molds from structures requires first that water problems be corrected. Then, the mold-infested material must be removed using proper protection. In some cases, heavily mold-infested structures have had to be demolished or burned. In order to make the best decision on how to treat a mold-polluted structure, it is important to understand what molds are present and in what amount.

A mycologist (scientist who studies molds) can often identify and count mold spores collected from indoor air, dust, or surfaces either by culturing them or by observing them under a microscope. However, these are slow and difficult processes.

In order for mycologists to improve their knowledge about molds in the indoor environment, mold DNA (i.e., moldgenomes) are being sequenced. Sequencing of DNA is the process of deciphering the spelling of the DNA alphabet that makes each organism unique.

Like the sequencing of the human genome, this knowledge of mold genomes allows molecular biologists to develop easier and faster methods for the detection and quantification of molds. This is important because all molds in the indoor environment cannot be eliminated. If molds can be monitored, experts can find out when mold concentrations are at dangerous levels. Measures can then be taken to reduce the mold pollution in the environment.

Noise Pollution

Noise pollution

Noise pollution is the intrusion of unwanted, uncontrollable, and unpredictable sounds, not necessarily loud, into the lives of individuals of reasonable sensitivities. Using the “reasonable person” standard removes the notion that the judgment of sounds as unwanted is subjective.

Unwanted sounds or noises can be traced back to Old Testament stories of very loud music and barking dogs as well as to ancient Rome where city residents complained about noisy delivery wagons on their cobblestone streets. The Industrial Revolution, the growth of cities, and the demand for transportation made the world even noisier.

With the modern world so dependent on and enchanted with noise-producing and noise-related technology—automobiles, aircraft, helicopters, motorcycles, snowmobiles, jet skis, leaf blowers, amplified music, bass-driven car stereo systems—the ambient noise level is rapidly accelerating. This growth in noise has led to research examining the impact of noise on the lives and activities of reasonable people. The result has been a body of evidence that strongly suggests noise is hazardous to good mental and physical health.


To understand noise, one must know something about sound and how loudness is measured. Sound that travels through the air in waves has two major properties: the frequency or speed at which the waves vibrate and the intensity of each vibration. It is the intensity, or how many molecules are packed together with each vibration, that for the most part produces the sense of loudness, although frequency also contributes to the determination of loudness, with higher-pitched sounds sounding louder.

Loudness is measured by a decibel scale (expressed as dB), but to reflect human hearing more accurately a modified version of this scale, known as the A scale, has been developed. On the A scale, loudness is measured in dBAs.

The scale increases logarithmically so that an increase of 10 dB indicates a doubling of loudness, and an increase of 20 dB represents a sound that is four times louder. Whispers measure 20 dBA, normal conversation 50 to 60 dBA, shouting 85 dBA, and loud music over 120 dBA. Continuous exposure to sounds over 85 dBA may cause permanent hearing loss.

Exposure to very loud sounds that are enjoyable, and not technically noise to the listener, can lead to hearing impairment. Because many people, especially young children and teenagers, are not aware of the dangers of very loud sounds to their hearing, they should be warned that playing computer games with loud audio attachments, setting headsets at consistently high volume, or regularly playing ball in a loud gymnasium may affect their hearing over time. A survey of hearing threshold shifts among youngsters between the ages of six and nineteen found that one out of eight of them suffered a noise-related hearing problem.

Children attending loud movies and sporting events, or visiting video arcades may be unwittingly exposing themselves to dangerously loud sounds. Teenagers are especially vulnerable as they are more likely to equip their cars with high-powered “boom boxes,” attend loud dance clubs, and work in noisy fast-food restaurants.

Sounds need not be very loud to be deemed intrusive—for example, the drip of a faucet, an overhead jet, or a neighbor’s stereo late at night. Noises are especially bothersome at night when one is trying to sleep, and a good night’s sleep is vital to good health. Exposure to bothersome noises over time can be stressful, resulting in adverse health effects, such as hypertension. Although more research is needed to solidify a noise and health link, there is agreement that noise lessens the quality of life.


Noises can be especially harmful to children. Scientific research indicates that noisy homes slow down cognitive and language development in young children. In addition, children living and attending schools near noisy highways, railroads, and airports have lower reading scores, and some children living or attending a school near a major airport have experienced elevated blood pressure.

In 1972 the U.S. government passed legislation recognizing the growing danger of noise pollution. It empowered the Office of Noise Abatement and Control (ONAC) within the Environmental Protection Agency (EPA) to curtail noise levels, but by 1982, during the Reagan administration, the office lost most of its funding.

States and cities were no longer supported in their efforts to abate noise, and ONAC no longer published materials educating people on the dangers of noise. Recently, the federal government has passed legislation to lessen noise in national parks, for example, banning snowmobiles, but states and cities are on their own in controlling noise, with some cities more successful than others.

aircraft noise

Traffic noise, especially aircraft noise, is the major source of annoyance calling for better federal regulation within the United States. In contrast, the European Union is finalizing a noise directive that will require member states to produce noise maps and develop action plans to reduce noise levels.

Noise from snowmobiles, jet skis, and supersonic jets has also intruded on the environment, affecting animals’ abilities to communicate, protect their young, and mate. Worldwide, antinoise groups believe their governments are doing too little to lessen the surrounding din, and groups from the United States, Europe, Canada, Australia, Africa, and Asia have joined together to educate both the public and governments about the long-term dangers of noise pollution, urging them to lower the decibel level. A quieter, healthier environment is within our grasp.

Nonpoint Source Pollution

Nonpoint Source Pollution

Nonpoint source pollution occurs when rainfall or snowmelt runs over land or through the ground, picks up pollutants, and deposits them into rivers, lakes, wetlands, and coastal waters or introduces them into groundwater. Some of the primary activities that generate nonpoint source pollution include farming and grazing activities, timber harvesting, new development, construction, and recreational boating.

Manure, pesticides, fertilizers, dirt, oil, and gas produced by these activities are examples of nonpoint source pollutants. Even individual households contribute to nonpoint source pollution through improper chemical and pesticide use, landscaping, and other house-hold practices.

After Congress passed the Clean Water Act in 1972, the water-quality community within the United States placed a primary emphasis on addressing and controlling point source pollution (pollution coming from discrete conveyances or locations, such as industrial and municipal waste discharge pipes). Not only were these sources the primary contributors to the degradation of U.S. waters at the time, but the extent and signficance of nonpoint source pollution were also poorly understood and overshadowed by efforts to control pollution from point sources.


At the beginning of the twenty-first century, nonpoint source pollution stands as the primary cause of water-quality problems within the United States. According to the National Water Quality Inventory (published by the U.S. Environmental Protection Agency), it is the main reason that approximately 40 percent of surveyed rivers, lakes, and estuaries are not clean enough to meet basic uses such as fishing or swimming.

Leading Contributors to Nonpoint Source Pollution

States and other jurisdictions reported in the National Water Quality Inventory that agriculture and urban runoff are among the leading contributors to deteriorating water quality nationwide. The most common nonpoint source pollutants causing water-quality problems include nutrients (nitrogen and phosphorus), siltation (soil particles), metals, and pathogens (bacteria and viruses).

Agriculture is identified as the leading source of degradation of polluted rivers, streams, and lakes surveyed by states, territories, and tribes in the National Water Quality Inventory. Agricultural activities that result in nonpoint source pollution include concentrated animal feeding operations (CAFOs), grazing, plowing, pesticide spraying, irrigation, fertilizing, planting, and harvesting.

A major nonpoint source pollutant from these activities is an excess of nutrients, which can occur through applications of crop fertilizers and manure from animal production facilities. Excessive nutrients may overstimulate the growth of aquatic weeds and algae, depleting the oxygen available for a healthy aquatic community.

Hydromodification that alters the flow of water is the second leading source of damage to U.S. rivers, streams, and lakes, according to the same National Water Quality Inventory report. Examples of hydromodification projects include channelization, dredging, and construction of dams.

Excess sediment due to erosion caused by projects such as building dams can severely alter aquatic communities by clogging fish gills or suffocating eggs. Sediment may also carry other pollutants into water bodies (e.g., PCBs or mercury) which can accumulate in aquatic species, leading to fish consumption advisories.

Habitat modification is identified as the third-largest source of water pollution in surveyed rivers and streams in the National Water Quality Inventory. Habitat modification occurs when the vegetation along stream banks is removed, diminishing buffers that help filter runoff and provide shade for the adjacent water body. These modifications can result in an increase in the water temperature (because of less shade) and an increase in quantity and velocity of runoff, making the river or stream less suitable for the organisms inhabiting it.

Urban runoff

Runoff from urban areas is the fourth-largest source of water pollution in rivers and streams and the third-largest source of water pollution in lakes, according to the National Water Quality Inventory. Increased urban development brings additional roads, bridges, buildings, and parking lots, which can result in large amounts of runoff that quickly and easily drain into rivers and lakes. In contrast, the porous and varied terrain of natural landscapes like forests, wetlands, and grasslands traps rainwater and snowmelt and allows it to filter slowly into the ground.

Urban runoff transports a variety of pollutants, including sediment from new development; oil, grease, and toxic chemicals from vehicles; and nutrients and pesticides from turf management and gardening. It can also carry pathogenic bacteria and viruses released from failing septic systems and inadequately treated sewage, which can result in closed beaches and shellfish beds, contaminated drinking water sources, and even severe human illness.

Programs for Nonpoint Source Control

The United States has made significant progress in addressing nonpoint source pollution since Congress amended the Clean Water Act in 1987 to establish a national program for controlling nonpoint source pollution. Under section 319 of the Clean Water Act, states adopted management programs to control nonpoint source pollution, and since 1990 the EPA has awarded grants to states to assist them in implementing those management programs.


Other federal agencies also provide technical and financial support through grants and loans to states, local communities, and farmers and other landowners, to implement nonpoint source pollution controls. In addition, many state and local entities are dedicating increasing amounts of funding to control nonpoint source pollution.

State nonpoint source programs provide for the control of nonpoint source pollution primarily through best management practices (BMPs), which are on-the-ground technical controls used to prevent or reduce nonpoint source pollution.

Common practices used to control nutrients from agriculture include altering fertilizer and pesticide application methods and storing and properly managing manure from confined animal facilities. Developing a buffer of vegetation between the land and the stream bank can help filter all types of nonpoint source pollutants from entering a receiving water body, including sediment transported by overland flow.

Stream-bank protection and channel stabilization practices are also very effective in preventing sediment deposition in the water by limiting the bank erosion processes and streambed degradation. Urban runoff can be controlled by establishing trenches, basins, and detention ponds at construction sites to hold, settle, and retain suspended solids and associated pollutants.

Basic pollution-prevention measures introduced around the home can also prevent nonpoint source pollutants from entering storm water. Practices include the proper storage, use, and disposal of household hazardous chemicals; proper operation and maintenance of onsite disposal systems; and even proper disposal of pet waste so that it does not wash into storm drains.

Watershed Approach to Managing Nonpoint Source Pollution

Nonpoint source pollution derives from many different sources over large geographic areas so regulating and controlling it are challenging. The watershed approach to managing nonpoint source pollution, however, is proving to be an effective technique. Everyone lives in a watershed, or an area of land in which all water drains.

According to the U.S. Geological Survey, the nation can be divided into approximately 2,149 medium-sized watersheds, averaging about 1,700 square miles in each area. The watershed approach relies on coordinating all relevant federal, state, and local government agencies, and the stakeholders who live in a particular watershed, to help solve priority problems in that watershed.

Historically, many water-quality problems were addressed piecemeal in individual water bodies by individual entities, usually limited by political, social, and economic boundaries. The watershed approach, however, relies on the coordination of all entities and stakeholders to help solve the watershed’s most serious environmental problems, which in many instances are caused by nonpoint source pollution.

International Implications

Managing nonpoint source pollution is an international challenge. Like the United States, many developed countries initially directed resources toward controlling point source pollution. However, significant nonpoint source problems remain, especially resulting from an excess of nutrients and sediment in water bodies. The United Nations Environment Programme has identified increased nitrogen loadings, resulting mainly from agricultural runoff and wastewater, as one of the most serious water-quality issues affecting all countries.

Sedimentation is a significant concern for other countries, frequently resulting from deforestation or clear cutting for fuelwood, or agricultural practices. One of the largest threats in developing countries relates to problems with sewage control, either through poor maintenance of sewage collection systems or a lack of it, leading to severe waterborne diseases.

The increasing world population promises even more challenges for managing nonpoint source pollution. Some international communities are embracing integrated solutions (like the watershed approach) to reduce it. Agenda 21 adopted at the United Nations Conference on Environment and Development in 1992 is but one example.

Ocean Dumping

Ocean dumping

Ocean disposal of society’s waste got its start indirectly long before the Agricultural Age when nearby streams, lakes, and estuaries were useful as waste repositories. As civilization moved to the coastal zone and navigation began in earnest, the oceans were viewed as even a larger waste repository.

Early civilizations were located adjacent to bodies of water for sources of food, irrigation, drinking water, transportation, and a place to dispose of unnecessary items. Historically, the disposal of wastes into water by humans was universally practiced.

It was a cheap and convenient way to rid society of food wastes (e.g., cleaned carcasses, shells, etc.), trash, mining wastes, and human wastes (or sewage). The advent of the Industrial Age brought with it the new problem of chemical wastes and by-products: These were also commonly disposed of in the water.


Early dumping started in rivers, lakes, and estuaries, whereas ocean dumping was simply not used because of the distance and difficulty in transporting waste materials. The wastes from ships, however, were simply dumped directly into the ocean.

As civilization developed at river deltas and in estuaries adjacent to the ocean, and these areas soon began to display the effects of dumping, disposal in the ocean became a popular alternative. Over the past 150 years, all types of wastes have been ocean dumped.

These include sewage (treated and untreated), industrial waste, military wastes (munitions and chemicals), entire ships, trash, garbage, dredged material, construction debris, and radioactive wastes (both high- and low-level). It is important to note that significant amount of wastes enter the ocean through river, atmospheric, and pipeline discharge; construction; offshore mining; oil and gas exploration; and shipboard waste disposal. Unfortunately, the ocean has become the ultimate dumping ground for civilization.

Towed, then dumped to the oceans floor

It has been recognized over the past fifty years that the earth’s oceans are under serious threat from these wastes and their “witches’ brew” of chemicals and nonbiodegradable components. Society has also come to understand that its oceans are under serious threat from overfishing, mineral exploration, and coastal construction activities.

The detrimental effects of ocean dumping are physically visible at trashed beaches, where dead fish and mammals entangled in plastic products may sometimes be observed. They are additionally reflected in the significant toxic chemical concentrations in fish and other sea life. The accumulations of some toxins, especially mercury, in the bodies of sea life have resulted in some harvestable seafood unfit for human consumption.

Seriously affected areas include commercial and recreational fishing, beaches, resorts, human health, and other pleasurable uses of the sea. During the 1960s numerous groups (global, regional, governmental, and environmental) began to report on the detrimental impact of waste disposal on the ocean. Prior to this time, few regulatory (or legal) actions occurred to control or prevent these dumping activities.

Pollution Shifting

Pollution Shifting

Pollution shifting is defined as the transfer of pollution from one medium (air, water, or soil) to another. Early legal efforts to control pollution focused on single media. For example, in the United States, the Clean Air Act covers air and the Clean Water Act covers water. However, pollution is not constrained by statute; it can shift between media by both natural and human action. Pollution management is improved when all media are considered.

Intentional pollution shifting may occur to destroy a pollutant, convert it to a safer form, or reduce its quantity or concentration. Examples of intentional pollution shifting include combustion, air stripping, air scrubbers, and adsorption. Intentional pollution shifting is accomplished by chemical reaction and/or mass transfer.

Chemical reactions can convert reactants in one media into products in a different media. In mass transfer shifting, differences in concentration are used to transfer pollutants from one media to another. For example, volatile compounds will transfer from relatively contaminated water to relatively clean air.


Combustion, Air Stripping, and Adsorption

Combustion is the process of burning, a chemical reaction. It involves combining combustible material with oxygen under conditions that produce light and heat in addition to by-products. The combustion of wastes, such as municipal solid waste, sludge, or hazardous waste, results in gaseous emissions and a solid ash residue. It significantly reduces the volume and mass of waste requiring disposal, by shifting some wastes to gaseous form.

Although carbon dioxide has been implicated in global warming, many of the gaseous emissions have no negative health impact, such as nitrogen gas, carbon dioxide, and water vapor. However, pollutants can also be present, including nitrogen oxides, sulfur dioxide, carbon monoxide, particulate matter, metals, acid gases, dioxins, and furans.

Contaminants in exhaust gases are minimized by optimization of the combustion process, for example, maintaining proper temperature and oxygen levels. They can also be captured with pollution-control equipment, such as air scrubbers and filters. In addition, the ash may contain hazardous compounds, such as heavy metals.

In air stripping, contaminates dissolved in water are transferred to gaseous form by contact with relatively clean air, an example of mass transfer. Air stripping works best with volatile organic compounds (VOCs) and dissolved gases. VOCs are compounds with high vapor pressures, that is, compounds that tend to evaporate quickly. A common application of air stripping is the cleanup of groundwater contaminated by leaking fuel storage tanks.

Air stripping

Air stripping is optimized by maximizing the surface area between the contaminated water and clean air, accomplished by creating fine water droplets in air or small air bubbles in water. Systems can be located away from the contamination (e.g., a system cleaning groundwater that is located on the earth’s surface), or located within the contaminated zone (e.g., a system located in wells installed in contaminated groundwater).

In some cases, the contaminated air from air stripping is released to the atmosphere, where the pollutants are destroyed by sunlight or reaction with other chemicals, adsorbed into soil or water, or diluted. Preferably, the organics in the exhaust from air stripping are destroyed by incineration or oxidation, or captured by adsorption.

The air stripping process may also be reversed. In air scrubbing, pollutants are transferred from contaminated air to clean water. However, a chemical reaction is often incorporated into air scrubbing, converting pollutants to a safer form.


For example, sulfur dioxide produced during coal combustion can be removed from exhaust gas by mass transfer to water containing sodium hydroxide or carbonate, which converts the sulfur dioxide to calcium carbonate. Natural air stripping and air scrubbing also occur. Surface waters, such as lakes and oceans, serve as sinks for pollutants released to the atmosphere. Contaminated water left exposed to the atmosphere will release VOCs.

The final pollution shift considered here is adsorption, in which a contaminant in water or air is adsorbed onto a solid material. Adsorption is use for off-gas control, groundwater remediation, landfill leachate treatment, industrial wastewater treatment, and water treatment for drinking or industrial purposes.

The most commonly used adsorbent is granular activated carbon (GAC). GAC has a tremendous amount of surface area per mass, on the order of one thousand square meters per gram. Its surface attracts many organic compounds; thus, a small amount of GAC can adsorb a significan amount of organic material. GAC may be regenerated, during which con taminants are destroyed.

Multimedia Approach

The multimedia approach to environmental management considers all media. It can be applied to single facilities, entire companies, and regions. According to the U.S. Environmental Protection Agency Multimedia Enforcement Division, it can result in:

• Improved detection and resolution of environmental compliance problems
• Achievement of optimal enforcement results
• More effective enforcement
• More efficient use of resources
• Fundamental changes in the regulated community’s perceptions and behavior regarding environmental compliance

Such benefits are realized by considering an entire pollution system, that is, all media.