BIOLOGICAL CONTAMINANTS

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Alan Robinson
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1 BIOLOGICAL CONTAMINANTS

2 Biological contaminants Bacteria carried by people and animals + soil and plant debris Viruses - transmitted by people and animals, wind and water Moulds grow on wet surfaces Pollens - originate from plants Animal dander sources are household pets Saliva mainly cat and rabbit saliva Dust mites - grow in damp, warm environments Insects ants, cockroaches, mice, rats, etc.

3 Humans as a source of biological contaminants During sneezing from to small drops of slime and saliva are released into indoor air, which can be the source of bacterial infections Small parts of skin can trigger asthma Clothing and bed linen are the source of bacteria and dust mites (for killing of most bacteria the washing temperature should be higher than 85 C)

4 Dust as a source of biological contaminants Domestic dust contains: organic particles (particles of dead insects, plant debris) sand (particles of paints, textiles, etc.) hairs, eyelashes pollen spores of moulds bacteria dust mites particles of excrements dust is a breeding ground for microbes producing mvoc (microbial volatile organic compounds)

5 Sources of biological contaminants During vacuum cleaning of carpets the amount of germs and spores of moulds Aspergillus, Alternaria, Cladosporium, Penicillium, Stachybotrys in indoor air increases 14 times Sweeping of floors results in 10 times higher amount of germs Mechanical removing of moulds from moulded surfaces may induce 3000 times higher amount of spores Opening doors to the cellar with moulded walls causes 1,5 times higher amount of spores in the living part of the house. Penicillium spores dominated.

6 Sources of biological contaminants Putting of 6 birch logs into the fireplace is the cause of 100 times greater amount of germs in the indoor air. One hour later the amount of germs was 30 times higher. Cleanup of moulded bread or opening of a jar with moulded jam induces 500 times higher amount of spores. 30 min later the amount was 170 times greater. Penicillium spores dominated. Return of a dog or a cat from the walk results in 10 times higher amount of spores. 30 min later the amount decreased to 30 %. Cladosporium spores dominated.

7 Sources of biological contaminants Replacement of hamster or rabbit bedding, if they are breeded indoors increases the amount of germs in indoor air to /m 3 Replacement of the bed sheet causes 3 times higher amount of germs in the bedroom. After 60 min concentration dropped back to the original values.

8 Health Effects From Biological Contaminants Children, elderly people, and people with breathing problems and allergies are particularly susceptible to diseases caused by biological agents. Symptoms of health problems sneezing watery eyes coughing shortness of breath dizziness lethargy fever digestive problems allergic reactions asthma

9 Health Effects From Biological Alllergic reactions hypersensitivity pneumonitis allergic rhinitis some types of asthma skin irritation (dermatitis) Contaminants Allergic reactions are caused mainly by pollen, dust mites and moulds. Allergic reactions occur only after repeated exposure to a specific biological allergen.

10 Bacteria Bacteria consist of only a single cell typically a few micrometers in length They have a wide range of shapes, ranging from spheres to rods and spirals They grow in soil, hot springs, radioactive waste, water as well as in organic matter and the live bodies of plants and animals. There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water Some are pathogens causing infectious diseases, including cholera, syphilis, anthrax and leprosy. The most common fatal bacterial diseases are respiratory infections (tuberculosis).

11 Sources of bacteria standing water and wet areas such as cooling coils, humidifiers, condensate pans, evaporation trays in air conditioners, dehumidifiers filters in air ducts (if they are not regularly replaced or washed) small indoor fountains water-damaged materials (carpets, etc.) household pets urine and excrements (pigeons, cats, etc.)

12 Legionella pneumophila A common inhabitant of water, cooling coils, humidifiers and HVAC systems Optimal water temperature for the growth of Legionella pneumophila is C (ideal conditions are in boilers, hot water distribution systems, etc.) In the air it survives, if the relative humidity is higher than 65% Human pathogen, which is responsible for legionellosis or Legionnaires` disease (pneumonia - infectious disease of lungs) In 1976 an outbreak of pneumonia occurred among people attending a convention of the American Legion in Philadelphia. This outbreak affected over 200 individuals, with 34 fatalities.

13 A common inhabitant of soil and water, it can cause serious illness in humans with: defective immune systems serious burns cystic fibrosis Pseudomonas fluorescens Frequently encountered in hospitals and resistant to most antibiotics and disinfectants.

14 Bacillus cereus Soil-dwelling bacterium that is responsible for foodborne illnesses causing severe nausea, vomiting and diarrhoea.

15 Mycobacterium sp. Typical for tap water even treated with chlorine, resistant to a number of antibiotics, mycobacterial infections are difficult to treat, can cause pulmonary disease resembling tuberculosis, lymphadenitis, skin disease or disseminated disease.

16 Streptococcus Streptococci cause: "strep throat Impetigo middle ear infections scarlet fever (a result of a toxin produced by the organism) rheumatic fever a rare form of toxic shock syndrome

17 Impetigo - highly infectious skin disease caused by staphylococcus bacteria or by the streptococcus bacteria Skin lesions

18 Staphylococcus aureus Some strains of Staphylococcus aureus secrete a toxin and can cause life-threatening toxic shock syndrome.

19 Moulds Basic information they can grow on any organic substance (wood, paper, carpet, plaster, foods, thermal insulation, etc.) the growth is conditioned by the presence of moisture and carbon they reproduce by means of spores; mould may begin growing when spores land on surfaces that are wet if the moisture problem remains undiscovered or unaddressed, the growth of mould often appears mould growth can be controlled by controlling moisture it is impossible to remove all moulds and spores from the indoor environment

20 Lifecycle of moulds SPORES SPORES = CONIDIA GERMINATION HYFENS CONIDIOPHORES MYCELIUM OF MOLDS MYCELIUM WITH CONIDIOPHORES

21 Health problems Moulds produce: allergens irritants toxic substances (mycotoxins) Inhaling, touching or ingestion of mould or mould spores may cause health problems. Allergic responses: sneezing runny nose red eyes skin rash (dermatitis) Asthma attacks Responses to irritants: eyes and skin irritation nose and throat irritation lung irritation Responses to mycotoxins: headache a pain in eyes fatigue

22 Moulds with allergic effects Acremonium sp. remains of plants, wet masonry, in basements Alternaria sp. DA. plants and their debris, occurrence mainly during spring and autumn Trichoderma viride timber, wet buildings, dust Aureobasidium pullulans dust, HVAC systems, latex paintings Botrytis cinerea DA. - plants and their debris, wet masonry Cladosporium sp. DA. wet masonry, plasters

23 Cladosporium sp.

24 Alternaria sp.

25 Botrytis sp.

26 Trichoderma viride

27 Acremonium sp.

28 Toxic substances produced by moulds Microbial volatile organic compounds (mvocs) - as a result of moulds metabolism mvocs may have a mouldy or musty odour mvocs produced by moulds are: alcohols, ketones, aldehydes, aromatic substances, amines, terpenes, chlorohydrocarbons, sulphur compounds and CO2 Serious health effects can occur, if the amount of mvocs in indoor air is greater than 2 g/m 3 mvocs are produced mainly by Penicillium, Aspergillus, Trichoderma, Alternaria, Fusarium, Paecilomyces

29 Fusarium sp.

30 Penicillium sp.

31 Toxic substances produced by moulds Aflatoxins produced by Aspergillus flavus, Penicillium, Rhizopus. Aflatoxins = deadly carcinogenic toxins, human pathogens, some may even grow through a person's lungs as if it were a loaf of bread, they cause a lung disease called Aspergillosis Aflatoxins produced by A. flavus and A. parasiticus killed great number of turkeys that had been fed by peanut meal contaminated with Aspergillus species (England in the early 1960's) Trichothecene mycotoxins produced by Stachybotrys chartarum reduce white blood cell count, which may lead to death

32 Aspergillus flavus

33 Stachybotrys chartarum

34 Deterioration of materials caused by moulds Mould gradually destroys the things it grows on. The longer it grows, the more damage it can cause.

35 Roof leakage Reasons for mould growth

36 Reasons for mould growth Rising damp (ineffective damp-proof course)

37 Reasons for mould growth Rainwater is collected near foundations (the ground is sloped towards the building, disconnected downpipes)

38 Reasons for mould growth Surface condensation on the inner surfaces of the building envelope (surface temperature is lower than is the temperature of the dew point, thermal bridges, high U value of the building envelope) Thermal bridges occur mainly in external and gable walls, roofs, floor structures above crawl spaces and unheated cellars, in outer 2D or 3D angles of the building and around frames of windows and external doors (inner sills, reveals and heads) External thermal insulation interrupted in places, where cantilevers or attic gables are connected to the load bearing structure

39 Reasons for mould growth 3D angle two external walls + roof Dew point temperature Termovision simulation

40 Reasons for mould growth 3D angle two external walls + roof Relative humidity

41 Reasons for mould growth 3D angle two external walls + roof

42 Reasons for mould growth Surface condensation on glazing Surface condensation on inner sills, reveals and heads caused by enormous infiltration of cold air through the joint between the built-in frame and the casement and through the joint between the wall and the built-in frame

indoor air higher than 60 % Very low air exchange

43 Reasons for mould growth Airtight finishing on the inner surfaces of external walls Relative humidity of indoor air higher than 60 % Very low air exchange rate Mould inside a bathroom cabinet Mould on shower curtain

44 Reasons for mould growth Built-in moisture inside structures (dangerous in combination with very low air exchange rate in newly completed houses, moisture is not efficiently removed, building drying-out is reduced) Insufficient crawl space ventilation Low temperature of indoor air Water penetration and cold air infiltration through joints between panels in prefabricated structures (ineffectively sealed joints or weathering of sealing material) Water leaks from pipes Surface condensation on pipes Contaminated central air handling systems

45 Investigation procedures visual inspection basic measurements (indoor air temperature and relative humidity, air movement, temperature of inner surfaces) finding out the composition of external walls and roof inspection of HVAC systems collecting mould samples for microscope examination no mould can be seen, but the building smells mouldy? HIDDEN MOULD

46 Investigation procedures Mould may be hidden in places such as: the back side of dry wall, wallpaper, or paneling, the top side of ceiling tiles, the underside of carpets and pads, etc. inside walls around pipes (with leaking or condensing pipes), the surface of walls behind furniture (where condensation forms)

47 Spores in indoor air Investigation procedures In spring, summer and autumn the amount of spores in indoor air is lower than in outdoor air In winter the amount of spores in indoor air is greater than in outdoor air

48 Category of bacterial contamination of indoor air (family houses, flats) Category Number of bacteria /m 3 Very low < 100 Low < 500 Medium < High < Very high >

49 Category of mould contamination of indoor air (family houses, flats) Category Number of mould spores /m 3 Very low < 50 Low < 200 Medium < High < Very high >

50 Reducing Exposure to Biological Contaminants General good housekeeping (the house should be kept clean by regular cleaning, room furnishings that accumulate dust should be avoided, especially if they cannot be washed in hot water, bedding should be washed in hot water with the temperature above 85 C, central vacuum systems that are vented to the outdoors or vacuums with high efficiency filters should be used) Maintenance of heating and air conditioning equipment (evaporation trays in air conditioners and dehumidifiers should be cleaned frequently, air filters should be replaced or washed regularly, humidifiers should be refilled with fresh water daily, etc.)

51 Reducing Exposure to Biological Contaminants Adequate ventilation and good air distribution (kitchens and bathrooms should be vented outdoors by exhaust fans or by opening windows, cellars and attic and crawl spaces should be ventilated to prevent water vapour condensation on or inside building structures) Maintaining the relative humidity between 30% - 50 % will help control mold Water damaged building materials and room finishings (carpets) should be cleaned and dried within 24 hours if possible, or removed and replaced

52 Reducing Exposure to Biological Contaminants Regular inspection, cleaning and repairing of roof gutters and downpipes Changing the slope of the ground away from the foundations so that rainwater cannot accumulate near foundations Immediate roof repairing if water penetrates through Fixing of plumbing leaks as soon as possible Covering cold water pipes and air ducts with thermal insulation in order to prevent surface condensation

53 Reducing Exposure to Biological Contaminants Installing of a new damp-proof barrier between foundations and walls Careful sealing of all joints around windows and external doors and between panels in prefabricated structures in order to minimize cold air infiltration resulting in cooling of inner sills, reveals and heads, on which afterwards surface condensation can occur Decreasing the U-value of external walls and roofs by placing additional thermal insulation (in case of walls preferably on their exterior surface). This measure increases temperature of interior surfaces and thus eliminates surface condensation.

54 Reducing Exposure to Biological Contaminants Frequent cleaning and disinfecting of refrigerators and freezers. Some genera of bacteria (Listeria, Yersinia, Aeromonas, Bacillus cereus) are able to withstand longterm exposition to low temperatures. Warming water in boilers to the temperature above 50 C in order to kill bacterium Legionella pneumophila Reducing the amount of biological contaminants on indoor surfaces or in indoor air by UV radiation produced by germicidal UV lamps Creating an air gap between furniture and walls at least 50 mm thick that enables free movement of indoor air

55 Cleaning mouldy areas Mould should be scrubbed off hard surfaces with detergent and water Scrubbed surfaces should be dried Wiping or scrubbing of surfaces with water and detergent or biocide Dry scrubbing can lead to a massive release of spores

56 Cleaning mouldy areas Person that cleans the mould should avoid exposing himself or others to mould and airborne spores. He should wear respirator, gloves and goggles. Touching mould or mouldy items with bare hands and getting mould into eyes should be avoided.

57 Cleaning mouldy areas If the contaminated area is large, a containment can be used to limit the spread of mould throughout the building and to minimize the exposure of building occupants to mould. By an exhaust fan the containment area can be maintain under negative pressure.

58 Cleaning mouldy areas Biocides should be applied on the affected surfaces (the type of the biocide must reflect the type of mould, two different types of biocides are recommended for one area) Application can be in the form of solutions, aerosols or fumes Area, where the biocides are used should be ventilated outdoors Time, during which the biocide creates sufficient protection against the mould growth, is usually 2 or 3 years (max. 5 years)

59 Biocides = chemical solutions that kill living organisms such as mould Requirements: ecology (no toxicity for environment as a bear, etc.) effectiveness (for most types of moulds) low concentration of toxic agents no reaction with the treated surfaces Biocides

60 Effectiveness can be reduced by higher dampness of building materials or by presence of bacteria Biocides

61 Biocides Alcohols (butanol, ethanol, ethylene oxide) Methylbromide Aldehydes (Formaldehyde) Acetic peroxo-acid Chlorine amine (20 30 % of chlorine)

62 Ultraviolet radiation produced by germicidal UV lamps wave lengths around 260 nm have the highest efficiency vegetative forms of microorganisms are killed within 30 s spores of bacteria and moulds are more resistant low doses of UV radiation may evoke higher resistance of microbes Damaged of DNA and proteins

63 Ionizing radiation Suitable for vegetative forms of microorganisms, which are sensitive to ionizing radiation Spores are resistant Low doses can have mutagenic effect Single treatment does not have long-term effect Suitable for small articles (fine arts, paintings, books, etc.)

Facts about Stachybotrys chartarum and Other Molds

Facts about Stachybotrys chartarum and Other Molds I heard about "toxic molds" that grow in homes and other buildings. Should I be concerned about a serious health risk to me and my family? (/mold/stachy.htm#q1)