Mold health issues are potentially harmful effects of molds.

Molds (US usage; British English "moulds") are ubiquitous in the biosphere, and mold spores are a common component of household and workplace dust. The United States Centers for Disease Control and Prevention reported in its June 2006 report, 'Mold Prevention Strategies and Possible Health Effects in the Aftermath of Hurricanes and Major Floods,' that "excessive exposure to mold-contaminated materials can cause adverse health effects in susceptible persons regardless of the type of mold or the extent of contamination." When mold spores are present in abnormally high quantities, they can present especially hazardous health risks to humans after prolonged exposure, including allergic reactions or poisoning by mycotoxins, or causing fungal infection (mycosis).

Symptoms of mold exposure may include nasal and sinus congestion; runny nose, eye irritation; itchy, red, watery eyes, respiratory problems, such as wheezing and difficulty breathing, chest tightness, cough, throat irritation, skin irritation (such as a rash), headache, and persistent sneezing.

Mold (American English) or mould (British English) is part of the natural environment. Outdoors, molds play a part in nature by breaking down dead organic matter such as fallen leaves and dead trees; indoors, mold growth should be avoided. Molds reproduce by means of tiny spores. The spores are invisible to the naked eye and float through the air. Mold may begin growing indoors when spores land on moist surfaces. There are many types of mold, but all require moisture for growth.

Snow mold is a type of fungus and a turf disease that damages or kills grass after snow melts, typically in late winter. Its damage is usually concentrated in circles three to twelve inches in diameter, although yards may have many of these circles, sometimes to the point at which it becomes hard to differentiate between different circles. Snow mold comes in two varieties: pink or gray. While it can affect all types of grasses, Kentucky bluegrass and fescue lawns are least affected by snow mold.

Symptoms of mold exposure can include:

- Nasal and sinus congestion, runny nose

- Respiratory problems, such as wheezing and difficulty breathing, chest tightness

- Cough

- Throat irritation

- Sneezing / Sneezing fits

Coal ash, also known as coal combustion residuals (CCRs), is the particulate residue that remains from burning coal. Depending on the chemical composition of the coal burned, this residue may contain toxic substances and pose a health risk to workers in coal-fired power plants.

Cork is often harvested from the cork oak ("Quercus suber") and stored in slabs in a hot and humid environment until covered in mold. Cork workers may be exposed to organic dusts in this process, leading to this disease.

Suberosis, also known as corkhandler's disease or corkworker's lung, is a type of hypersensitivity pneumonitis usually caused by the fungus "Penicillium glabrum" (formerly called "Penicillum frequentans") from exposure to moldy cork dust. "Chrysonilia sitophilia", "Aspergillus fumigatus", uncontaminated cork dust, and "Mucor macedo" may also have significant roles in the pathogenesis of the disease.

Cladosporium fulvum is an Ascomycete called "Passalora fulva", a non-obligate pathogen that causes the disease on tomato known as the Tomato leaf mold. P. fulva only attacks tomato plants, especially the foliage, and it is a common disease in the greenhouses, but can also occur in the field. The pathogen is likely to grow in humid and cool conditions. In the greenhouses, this disease causes big problems during the fall, in the early winter and spring, due to the high relative humidity of air and the temperature, that are propitious for the leaf mold development. This disease was first described in the North Carolina, by Mordecai Cubitt Cooke (1883), on cultivated tomato (Cooke 1883), although it is original from South and Central America. The causal fungus of tomato leaf mold may also be referred as Cladosporium fulvum (Cooke 1883), a former name.

Initial symptoms include large, angular or blocky, yellow areas visible on the upper surface. As lesions mature, they expand rapidly and turn brown. The under surface of infected leaves appears watersoaked. Upon closer inspection, a purple-brown mold (see arrow) becomes apparent. Small spores shaped like footballs can be observed among the mold with a 10x hand lens. In disease-favorable conditions (cool nights with long dew periods), downy mildew will spread rapidly, destroying leaf tissue without affecting stems or petioles.

Gray snow mold ("Typhula" spp. or Typhula blight) is the less damaging form of snow mold. While its damage may appear widespread, it typically does little damage to the grass itself, only to the blades. Unlike most plant pathogens, it is able to survive throughout hot summer months as sclerotia under the ground or in plant debris. Typhula blight is commonly found in United States in the Great Lakes region and anywhere with cold winter temperatures and persistent snow fall.

Downy mildew refers to any of several types of oomycete microbes that are obligate parasites of plants. Downy mildews exclusively belong to Peronosporaceae. In commercial agriculture, they are a particular problem for growers of crucifers, grapes and vegetables that grow on vines. The prime example is "Peronospora farinosa" featured in NCBI-Taxonomy and HYP3. This pathogen does not produce survival structures in the northern states of the United States, and overwinters as live mildew colonies in Gulf Coast states. It progresses northward with cucurbit production each spring. Yield loss associated with downy mildew is most likely related to soft rots that occur after plant canopies collapse and sunburn occurs on fruit. Cucurbit downy mildew only affects leaves of cucurbit plants.

, one of the Four Big Pollution Diseases of Japan, occurred in the city of Yokkaichi in Mie Prefecture, Japan, between 1960 and 1972. The burning of petroleum and crude oil released large quantities of sulfur oxide that caused severe smog, resulting in severe cases of chronic obstructive pulmonary disease, chronic bronchitis, pulmonary emphysema, and bronchial asthma among the local inhabitants. The generally accepted sources of the sulfur oxide pollution were petrochemical processing facilities and refineries that were built in the area between 1957 and 1973.

Zygomycosis is the broadest term to refer to infections caused by "bread mold fungi" of the zygomycota phylum. However, because zygomycota has been identified as polyphyletic, and is not included in modern fungal classification systems, the diseases that zygomycosis can refer to are better called by their specific names: mucormycosis (after Mucorales), phycomycosis (after Phycomycetes) and basidiobolomycosis (after Basidiobolus). These rare yet serious and potentially life-threatening fungal infections usually affect the face or oropharyngeal (nose and mouth) cavity. Zygomycosis type infections are most often caused by common fungi found in soil and decaying vegetation. While most individuals are exposed to the fungi on a regular basis, those with immune disorders (immunocompromised) are more prone to fungal infection. These types of infections are also common after natural disasters, such as tornadoes or earthquakes, where people have open wounds that have become filled with soil or vegetative matter.

The condition may affect the gastrointestinal tract or the skin. In non-trauma cases, it usually begins in the nose and paranasal sinuses and is one of the most rapidly spreading fungal infections in humans. Common symptoms include thrombosis and tissue necrosis. Treatment consists of prompt and intensive antifungal drug therapy and surgery to remove the infected tissue. The prognosis varies vastly depending upon an individual patient's circumstances.

Blight refers to a specific symptom affecting plants in response to infection by a pathogenic organism. It is a rapid and complete chlorosis, browning, then death of plant tissues such as leaves, branches, twigs, or floral organs. Accordingly, many diseases that primarily exhibit this symptom are called blights. Several notable examples are:

- Late blight of potato, caused by the water mold "Phytophthora infestans" (Mont.) de Bary, the disease which led to the Great Irish Famine

- Southern corn leaf blight, caused by the fungus "Cochliobolus heterostrophus" (Drechs.) Drechs, anamorph "Bipolaris maydis" (Nisikado & Miyake) Shoemaker, incited a severe loss of corn in the United States in 1970.

- Chestnut blight, caused by the fungus "Cryphonectria parasitica" (Murrill) Barr, has nearly completely eradicated mature American chestnuts in North America.

- Fire blight of pome fruits, caused by the bacterium "Erwinia amylovora" (Burrill) Winslow "et al.", is the most severe disease of pear and also is found in apple and raspberry, among others.

- Bacterial leaf blight of rice, caused by the bacterium "Xanthomonas oryzae" (Uyeda & Ishiyama) Dowson.

- Early blight of potato and tomato, caused by species of the ubiquitous fungal genus "Alternaria"

- Leaf blight of the grasses

On leaf tissue, symptoms of blight are the initial appearance of lesions which rapidly engulf surrounding tissue. However, leaf spot may, in advanced stages, expand to kill entire areas of leaf tissue and thus exhibit blight symptoms.

Blights are often named after their causative agent, for example Colletotrichum blight is named after the fungi "Colletotrichum capsici", and Phytophthora blight is named after the water mold "Phytophthora parasitica".

Farmer’s lung reactions can be categorized as acute and chronic reactions. Acute and chronic reactions have the same symptoms but for chronic reactions, the symptoms are much more severe. Farmer’s lung symptoms include:

- Chills

- Fever

- Irritating/harassing cough

- Runny nose

- Sputum streaked with blood

- Tightness of the chest

- Difficult and laboured breathing

- Crackling of breath

- Muscular pain

- Depression

These symptoms develop between four and eight hours after exposure to the antigens. In acute attacks, the symptoms mimic pneumonia or flu. In chronic attacks, there is a possibility of the victim going into shock and dying from the attack.

The signs and symptoms of allergies in a child are:

- Chronic symptoms resembling the cold that last more than a week or two.

- Cold-like symptoms that appear during the same time each year

- Repeated difficulty breathing, wheezing and breathing

- Cold-like symptoms that happen at night

- Cold-like symptoms that happen during exercise

- Chronic rashes or patches of skin that are dry, itchy, look like scales

- Cold-like symptoms that appear after eating a certain food

- Hives

- Swelling of face, arms or legs

- Gagging, coughing or wheezing, vomiting or significant abdominal pain

- Itching or tingling sensations in the mouth, throat or ears

Farmer's lung (not to be confused with silo-filler's disease) is a hypersensitivity pneumonitis induced by the inhalation of biologic dusts coming from hay dust or mold spores or any other agricultural products. It results in a type III hypersensitivity inflammatory response and can progress to become a chronic condition which is considered potentially dangerous.

A toxic tort claim is a specific type of personal injury lawsuit in which the plaintiff claims that exposure to a chemical or dangerous substance caused the plaintiff's injury or disease.

Sick building syndrome (SBS) is a medical condition where people in a building suffer from symptoms of illness or feel unwell for no apparent reason. The symptoms tend to increase in severity with the time people spend in the building, and improve over time or even disappear when people are away from the building. The main identifying observation is an increased incidence of complaints of symptoms such as headache, eye, nose, and throat irritation, fatigue, and dizziness and nausea. These symptoms appear to be linked to time spent in a building, though no specific illness or cause can be identified. SBS is also used interchangeably with "building-related symptoms", which orients the name of the condition around patients rather than a "sick" building. A 1984 World Health Organization (WHO) report suggested up to 30% of new and remodeled buildings worldwide may be subject of complaints related to poor indoor air quality.

Sick building causes are frequently pinned down to flaws in the heating, ventilation, and air conditioning (HVAC) systems. However, there have been inconsistent findings on whether air conditioning systems result in SBS or not. Other causes have been attributed to contaminants produced by outgassing of some types of building materials, volatile organic compounds (VOC), molds (see mold health issues), improper exhaust ventilation of ozone (byproduct of some office machinery), light industrial chemicals used within, or lack of adequate fresh-air intake/air filtration (see Minimum efficiency reporting value).

Human exposure to bioaerosols has been documented to give rise to a variety of adverse health effects. Building occupants complain of symptoms such as sensory irritation of the eyes, nose, or throat; neurotoxic or general health problems; skin irritation; nonspecific hypersensitivity reactions; infectious diseases; and odor and taste sensations. Exposure to poor lighting conditions has led to general malaise.

Extrinsic allergic alveolitis has been associated with the presence of fungi and bacteria in the moist air of residential houses and commercial offices. A very large 2017 Swedish study correlated several inflammatory diseases of the respiration tract with objective evidence of damp-caused damage in homes.

The WHO has classified the reported symptoms into broad categories, including: mucous membrane irritation (eye, nose, and throat irritation), neurotoxic effects (headaches, fatigue, and irritability), asthma and asthma-like symptoms (chest tightness and wheezing), skin dryness and irritation, gastrointestinal complaints and more.

Several sick occupants may report individual symptoms which do not appear to be connected. The key to discovery is the increased incidence of illnesses in general with onset or exacerbation within a fairly close time frame—usually within a period of weeks. In most cases, SBS symptoms will be relieved soon after the occupants leave the particular room or zone. However, there can be lingering effects of various neurotoxins, which may not clear up when the occupant leaves the building. In some cases—particularly in sensitive individuals—there can be long-term health effects.

In 1955, the Ministry of International Trade and Industry began its policy to transition Japan's primary fossil fuel source from coal to petroleum. To accomplish that goal, construction of the Daichi Petrochemical Complex was begun in 1956. The complex contained an oil refinery, a petrochemical plant, and a power station. This was the first petrochemical complex constructed in Japan.

In 1960, the government of Prime Minister Hayato Ikeda accelerated the growth of petrochemical production as part of its goal to double individual incomes of Japanese citizens over a 10-year period. Also in 1960, MITI announced that a second complex was to be constructed on reclaimed land in northern Yokkaichi. The second complex went online in 1963. As demand for ethylene and other petrochemicals rose, a third complex was constructed which began production in 1972. Yokkaichi transferred its energy production from coal to oil more quickly than the rest of the nation. The oil used in Yokkaichi was primarily imported from the Middle East, which contained 2% sulfur in sulfur containing compounds, resulting in a white-colored smog developing over the city.

People may be exposed to toxic chemicals or similar dangerous substances from pharmaceutical products, consumer products, the environment, or in the home or at work. Many toxic tort cases arise either from the use of medications, or through exposure at work.

The tomato leaf mold fungus is a specific pathogen of tomato plant Lycopersicon, this pathogen has restricted host range (host specific pathogen) that only infects tomatoes, mainly greenhouses.

The symptoms of this disease commonly occurs on foliage, and it develops on both sides of the leaf on the adaxial and abaxial surface. The older leaves are infected first and then the disease moves up towards young leaves.

Symptoms of tomato leaf mold appear usually with foliage, but fruit infection is rare. The primary symptom appear on the upper surface of infected leaves as a small spot pale green or yellowish with indefinite margins, and on corresponding area of the lower surface, the fungus begins to sporulate. The diagnostic symptom develops on lower surface as an olive green to grayish purple and velvety appearance, which are composed of spores (conidia). Continuously, the color of the infected leaf changes to yellowish brown and the leaf begins to curl and dry. The leaves will drop upon reaching a premature stage, and the defolication of the infected host will cause further infection. This disease develops well in relatively humidity levels (above 85%). When the temperature reaches optimum level for germinating, the host will be infected by the pathogen. Occasionally, this pathogen causes disease on the fruit or blossoms with various symptoms. Fruits such as green and ripe one will develop dark rot on the stem. The blossoms will be killed before fruits grow.

Pathogenic zygomycosis is caused by species in two orders: Mucorales or Entomophthorales, with the former causing far more disease than the latter. These diseases are known as "mucormycosis" and "entomophthoramycosis", respectively.

- Order Mucorales (mucormycosis)

- Family Mucoraceae

- "Absidia" ("Absidia corymbifera")

- "Apophysomyces" ("Apophysomyces elegans" and "Apophysomyces trapeziformis")

- "Mucor" ("Mucor indicus")

- "Rhizomucor" ("Rhizomucor pusillus")

- "Rhizopus" ("Rhizopus oryzae")

- Family Cunninghamellaceae

- "Cunninghamella" ("Cunninghamella bertholletiae")

- Family Thamnidiaceae

- "Cokeromyces" ("Cokeromyces recurvatus")

- Family Saksenaeaceae

- "Saksenaea" ("Saksenaea vasiformis")

- Family Syncephalastraceae

- "Syncephalastrum" ("Syncephalastrum racemosum")

- Order Entomophthorales (entomophthoramycosis)

- Family Basidiobolaceae

- "Basidiobolus" ("Basidiobolus ranarum")

- Family Ancylistaceae

- "Conidiobolus" ("Conidiobolus coronatus/Conidiobolus incongruus")