When mold spores are present in abnormally high quantities, they can present especially hazardous health risks to humans, including allergic reactions or poisoning by mycotoxins, or fungal infection (mycosis). Studies have shown that people who already suffer from allergies, asthma, or compromised immune systems are at an increased risk of health problems such as inflammatory and toxic responses.
Most fungi are not dangerous, but some types can be harmful to health. Fungal diseases in the lungs are often similar to other illnesses such as the flu or tuberculosis. The spores of a large number of important fungi are less than 5 microm aerodynamic diameter, and therefore are able to enter the lungs. They also may contain significant amounts of mycotoxins.
Pollen is a very fine powder that comes from trees, grasses, flowers and weeds. Some anemophilous plants can produce large quantities of lightweight pollen, which can be carried for great distances and are easily inhaled, bringing it into contact with the sensitive nasal passages. In people who are susceptible, this causes allergy and asthma symptoms (known as hay fever, pollinosis or allergic rhinitis).
Dust mites are microscopic, insect-like pests that generate some of the most common indoor allergens that can trigger allergic reactions and asthma in many people. Hundreds of thousands of dust mites can live in the bedding, mattresses, upholstered furniture, carpets or curtains of your home. They feed on the dead human skin cells found in dust and the harmful allergen they create comes from their fecal pellets and body fragments. Dust mites are nearly everywhere; roughly four out of five homes have detectable levels of dust mite allergen in at least one bed.
Bacteria and viruses are airborne pathogens that may be spread through coughing, sneezing, raising of dust, spraying of liquids, or similar activities likely to generate aerosol particles or droplets. These airborne diseases often cause inflammation in the nose, throat, sinuses and the lungs. This is caused by the inhalation of these pathogens that affect a person's respiratory system or even the rest of the body. Sinus congestion, coughing and sore throats are examples of inflammation of the upper respiratory air way due to these airborne agents.
Pet dander is composed of tiny, even microscopic, flecks of skin shed by cats, dogs, rodents, birds and other animals with fur or feathers. Pet allergens can remain suspended in the air for a long time because of their microscopic size and jagged shape. People with allergies may experience upper and lower respiratory tract symptoms including congestion, sneezing, runny nose, chest tightness and wheezing. Other symptoms are itching, watery eyes, and eczema or rashes.