Microbiological and biological risks of staying in buildings

The issue of microbiological contamination of air conditioning in medical facilities is important, which can be one of the ways of spreading nosocomial infections. The risk increases with poorly operated air conditioning systems, where, for example, pathogenic or potentially pathogenic bacteria , fungi or yeast can spread to living and working areas. Another risk is allergenic effects. Specific types of infectious diseases appear in areas with a significant expansion of air conditioners, high-capacity humidifiers and coolers: the most well-known is Legionnaires' disease , caused by Legionella pneumophila. The microbe has adapted to life in "air washers" and humidifiers included in air conditioning systems and through them enters living and working areas; therefore, this damp part of the air conditioning is a high-risk area. In addition to legionella, other microorganisms, such as pseudomonads and fungi, can multiply here. Another, less serious disease is, for example, a short-term febrile illness called "humidifier fever". Therefore, there is an effort to replace these parts of the equipment with more modern, less risky ones - such as steam humidification and efficient air filtration.

Legionella
More detailed information can be found on the Legionellosis page .

Source
External environment (water, construction dust, dry mud).

Transmission
Dust or aerosol aspiration (cooling towers, air conditioners, incubators, showers, humidifiers).

Legionnaires disease

 * pneumonia
 * 20% mortality.
 * Mostly immunocompromised or alcoholics get sick.
 * It tends to be difficult.
 * Beware of air-conditioned rooms.
 * Upper grade (ratio of number of patients to infected) = 5%.

Pontiac fever
An affair in our country that drew attention to this infection: IKEM in Prague-Krč, a transplant center where 6 patients died after surgery, became infected with instant drinks (tap water).

Influenza of the upper respiratory tract


 * Flu symptoms,
 * lighter,
 * lasts 3-4 days.
 * Upper grade = 5%.

Prevention
Focus on the source - the outdoor environment is considered to be the source. Technical water: carry out distribution inspections. Water must flow through the pipes, it must not stand. It is also possible to chlorinate, treat with UV radiation or ionizers, and clean with membrane filters.

"Overheat and rinse" - every 1st Monday of the month (or other day) in hospitals and other facilities, water is heated more than usual and left for 3-5 minutes. flow from the tap. Temperature required to eliminate legionella: 80 ° C - legionella dies in seconds, 70 ° C in minutes , 60 ° C in several minutes. All it takes is one long pipe, one room with a tap that no one will let open at a given time, and the legionella will return and multiply.

Heat water at home - otherwise it's a risk for immunocompromised individuals, especially when showering.

The disadvantages of thermodisinfection are the economic cost and damage to water supply equipment. Products for chemical disinfection of hot water distribution and air conditioning systems are also commercially available.

Mold
Especially in the communal environment, the issue of the occurrence of mold is common. Fungi are microscopic and eukaryotic organisms that are otherwise widely distributed in the environment. Fungal spores are found in significant numbers in soil, dust, sticking to plants, surfaces. Under suitable conditions, such as temperature and especially ambient humidity, the spores germinate into vegetative forms and form mycelia. Aspergillus, Cladosporium, Alternaria, Rhizopus and Mucor are among the most common in the communal environment. Some prevalence of mold in the environment is considered common and does not pose an increased health risk to most people. The usual amount of fungi in the human environment is in the order of tens to hundreds of colony forming units (KTJ ) mixed mold populations in 1 m 3 of air. A good level of pollution is considered to be a concentration of molds in households in the range of 100 to 1000 CTU mixed mold populations / m 3 of air, unless risk factors for the spread of molds in the air are present.

Risk factors
Humidity is a risk factor for the spread of mold in the building environment. The most common sources of increased humidity in the indoor environment are construction-technical defects of structures (leakage during rains, leaks in piping systems), insufficient insulation against soil, moisture penetration into buildings, improper use of buildings and human activity (cooking, laundry, plant cultivation, insufficient ventilation, use of older types of plastic windows). The issue of so-called thermal bridges is serious. These are places in building structures that are characterized by increased thermal conductivity of the material. In winter, this causes the building structures to freeze. The warm air in the interior then cools in contact with the cold surface and condensation water settles on the surface.

Health implications
People who live in an environment that is characterized by increased humidity and thus promotes the spread of mold are at risk of allergic respiratory diseases (allergic rhinitis to bronchiolar asthma). An existing allergic disease may worsen. Non- specific problems such as conjunctival and airway mucosa, pressure or chest pain, headache, nausea and others are also reported. The mechanism of all adverse health effects of fungi on human health has not yet been fully elucidated, but the concomitant antigenic action of the allergen together with the toxic effects of MVOC is expected.

Prevention
Mold prevention is based on eliminating the conditions that allow the spread of mold in the indoor environment. The basic preventive measure is the identification of the source of moisture and the subsequent remediation of this source (repair of the building structure, installation of domestic hoods). Infected items with a low value are best disposed of. We will try to decontaminate the surfaces of building structures and valuables with a chemical disinfectant with an antifungal effect, following the manufacturer's instructions. We always remove mold from the surface after wetting, in order to prevent the spread of mold spores into the space. We proceed similarly when trying to remove the infested plaster. All mold-infested waste is disposed of as normal household waste.

Legislation
Legislatively, it is enshrined in Decree No. 268/2009 Coll. on the technical requirements for construction works that any construction work must be designed and constructed so as not to endanger the lives and health of persons, eg due to the presence or release of dangerous particles. The issue of molds is regulated especially for some types of constructions by Decree No. 6/2003 Coll., which sets hygienic limits of chemical, physical and biological indicators for the indoor environment of living rooms in some buildings. However, it only applies to accommodation rooms for educational establishments, universities, outdoor schools, accommodation rooms for buildings for convalescent events, buildings for medical facilities, medical and preventive care, social care institutions, accommodation facilities, buildings for trade and buildings for collecting a larger number persons (such as cultural facilities). It is stated that the visible growth of mold on the walls and surfaces of the living rooms is unacceptable; the suspected growth of the fungus shall be verified by a microbiological method. The concentration limit for the number of molds in the air is 500 CTU / m 3mixed fungal populations. The standard methodology of air sampling is based on the active suction of air by an aeroscope onto the nutrient medium intended for the cultivation of fungi, the limit value is compared with the average value calculated from two measurements.

Related Articles

 * Consequences of staying in buildings
 * Legionellosis

Source

 * BENCKO, Vladimir, et al. Hygiene: Textbooks for seminars and practical exercises. 2nd edition. Prague: Karolinum, 1998.  ISBN 80-7184-551-5.


 * World Health Organization. WHO Guidelines for Indoor Air Quality - Dampness and Mold  [online]. © 2009. [feeling. 2011-05-30]. < http://www.euro.who.int/__data/assets/pdf_file/0017/43325/E92645.pdf >.


 * State Institute of Public Health. Standard operating procedures for the examination of micro-organisms in the air and for the assessment of microbiological air pollution in the indoor environment. Acta Hygienica Epidemiologica et Microbiologica. 2002, vol. -, vol. 1, pp. -, ISSN 0862-5956.

Category :
 * Czech Republic. Ministry of Health. Decree No. 6/2003 Coll. laying down hygienic limits of chemical, physical and biological indicators for the indoor environment of living rooms in certain buildings. In 2003 . 2003.


 * Hygiene
 * Microbiology