BIOAEROSOLS

1. BIOAEROSOLS

2. Introduction • Bioaerosols are integral part of our ecological system and play an important role in its balance • Viruses, bacteria, fungi etc. are collectively called airborne biological contaminants or Bioaerosols • Outdoor control of Bioaerosols is usually not possible but indoors, it is achievable • Most of the Bioaerosols host on humans and moist places, which provide habitable conditions

3. General health Effects • Bioaerosols induce into human body by inhalation or by deposition on wounds • A possible reason of sick building syndrome (SBS) is the presence of Bioaerosols in the building. • Despite the defense mechanism of the body these Bioaerosols could cause damage to the body • The infections caused due to the Bioaerosols include: • Legionnaire’s disease • Humidifier fever • Cold • Influenza

4. Health Effects of Bioaerosols • Viruses: Common cold, Influenza, Measles, Bronchitis Rheumatic fever, Otitis media, Carditis, Diphtheria Whooping cough, Tuberculosis, Meningitis and Q – fever • Fungi: Histoplasmosis, Cocciodomycosis and Blastomycosis • Antigens: Allergic diseases of hypersensitivity pneumonitis (HP) Allergic asthma, Rhynitis and Pergillosis

5. FUNGI • Fungi play a major role causing many ill-effects. • These are found in very ecological niche, and are necessary in the recycling of organic building blocks that allow plant and animal lives to thrive. • Fungi need external organic food sources and water to survive. • Various groups of fungi are: • Yeasts • Molds • Mildews • Let us now know about molds, greatest problem creator for the researchers now.

6. Molds • Molds can grow on clothes, carpets, leather, wood, sheet rock, insulation and on human foods wherever moist conditions exist. • As molds flourish in moist or wet indoor conditions, human exposure is possible either by direct contact on surfaces or through the air if mold spores, fragments, or mold products are airborne. • Mold reproduction is done by production of spores. • To support the mold growth proper conditions and food sources are provided by wet indoor spaces with inorganic materials. • People are exposed to this mold spores or fragments through inhalation or by contact through small breaks in skin.

7. Various effects of molds • Effects of molds depend mainly on • Species of mold • Metabolic products being produced by molds • Amount and duration of individual’s exposure to mold parts or products • Specific susceptibility of those exposed. • Various health effects: • Allergy • Infection • Irritation (mucous membrane and sensory) • Toxicity

8. Allergy • This is the most common response from people to mold. • People who are genetically capable of producing an allergic reaction are referred to as atrophic. • When an atrophic person’s respiratory system or skin is exposed to mold or mold products that have become sensitized, symptoms will be developed. • Allergic reactions range from mild transitory responses, to severe chronic illnesses. • In Americans one in every five suffer from allergic rhinitis, the single most common disease that is experienced by humans. • Thousands of different molds contaminate indoor air, purified allergens have been recovered from only a few. • So, atrophic individuals may be exposed to molds found indoors and develop sensitization, yet not be identified as having mold allergy.

9. Infection • Infection from molds that grow indoor is not common. • A number of Aspergillus species that are found indoors are known to be pathogenic. • Most of the infections occur among immune-compromised patients, whoa re suffering from various causes as well. • Such infections mostly effect the skin, eyes and lungs and are also known to effect other organs or systems.

10. Mucous Membrane and Trigeminal Nerve Irritation • This type of irritation is derived from VOC’s that are produced by fungal metabolism. • Alcohol or aldehydes and acidic molecules may be produced by this fungi. • The nature of the food source from which the fungus grows may result in pungent primary metabolic products, for instance, one fungus growing on wall paper released the highly toxic gas arsenic from arsenic containing pigments. • Fungal volatile compounds may also impact the “common chemical sense” associated with the trigeminal nerve, which is a mixed (motor and sensory) nerve that responds to pungency, not odor, by initiating avoidance reactions such as breath holding, paresthesias, itching, burning, skin crawling, dilation of surface blood vessels, decreased attention, disorientation, diminished reflex time, dizziness etc.

11. Toxicity • Molds can also produce myotoxins, that are nearly cytotoxic and interfere with vital cellular processes such as protein, RNA and DNA synthesis. • Mold toxins increase the susceptibility of the exposed person to infectious diseases, reduce the ability of their defense system to fight against other contaminants and can also increase susceptibility to cancer.

12. Sources

13. Sources of Bioaerosols • Major sources of bacteria and viruses are humans and pets - sneezing, coughing, dander and saliva • Fungi, many bacteria, protozoa, algae and green plants (pollen) are present outdoors that are induced indoors by natural or mechanical ventilation • Moist surfaces of leather, wood, carpets, soaps, cloth fabric, some pastes and adhesives are examples of amplification sites • Breeding sites for fungi and bacteria are humidifiers, air conditioning systems, cooling towers, air distributing systems and areas of water damage

14. Types, Sizes, Pathogenic properties and Common sources of selected Bacteria

15. Types, Sizes, Pathogenic properties and Common sources of selected Fungi

16. Types, Sizes, Pathogenic properties and Common sources of selected Viruses

17. Introduction to sampling Techniques • The sampling techniques are usually same as for other particles, but the different types in Bioaerosols complicate the process • Several factors are considered to get positive or conclusive reports: • Not one sample is good for collecting all types of microorganisms • No sampling device provides for 100% recovery of Bioaerosols • The viability of Bioaerosol samples should be maintained in the sampler for subsequent growth and identification • Efficiency of the sampler depends on the size of the particular organism

18. Factors affecting choice of Sampling Techniques • Growth and survival of the individual organism depends on the humidity, temperature and pH of the culture medium • Proper selection of sampling and identification media is necessary for accurate sampling analysis • Samplers must be calibrated and used according to the manufacturer’s flow rate specifications • Since no method is available for collection and identification or counting of all Bioaerosols of interest, the selection of a method is guided by what is suspected to be present

19. Samplers available • Diffusive samplers • Moulton air samplers • Settling samplers • Dip stickle samplers • Filters • All-glass Impingers (AGI) • Impactors

20. Samplers preferred • High volume filters • High volume electrostatic precipitators • AGI • Impactors: • Anderson impactors • Silt impactors

21. Recommended samplers as per volume to be handled

22. Control Strategies • Source Removal • After identifying the airborne microorganisms the source can either be eliminated or its strength can be reduced • Regular Maintenance • Preventive maintenance is one the most effective ways to control the microorganisms indoors • Maintenance of air handling systems and fan coil units, drain pans and periodic replacement of the filters • Humidifiers using the re-circulated water should not be used. Steam should be used instead of cold water in humidifiers, heating and HVAC systems • Disinfectants and biocides should be used in the humidifier water reservoirs, which kill the microorganisms • Shock dosages have better results compared to the regular dosages

23. Biocides for controlling the most common Legionella pneumophilia : • Quaternary ammonia compounds • 1-bromo3-chloro-5 • 5-dimethyl-hydantoin • Bis(tri-n-butyltin)oxide • n-alkyl-1 • Methylene-bis • Dithiocarbamates • Chlorine

24. Methods for controlling molds • There is no practical way to eliminate mold and mold spores in the indoor environment, the way to control indoor mold growth is to control moisture. • If mold problem is their in your house or school, you must clean up the mold and eliminate sources of moisture. • Fix the source of water problem or leak to prevent mold growth. • Reduce indoor humidity ( to 30%-60%) to decrease mold growth by: - Venting bathrooms, dryers and other moisture-generating sources to the outside - using air conditioners and de-humidifiers - Increasing ventilation - Using exhaust fans whenever cooking, dishwashing and cleaning

25. Methods for controlling molds (contd…) • Clean and dry any damp or wet building materials and furnishings within 24-48 hours to prevent mold growth. • Clean mold off hard surfaces with water and detergent, and dry completely. Absorbent materials such as ceiling tiles, that are moldy, may need to be replaced. • Prevent condensation:Reduce the potential for condensation on cold surfaces (i. e. ,windows, piping, exterior walls, roof, or floors) by adding insulation. • In areas where there is a perpetual moisture problem, do not install carpeting (i. e. , by drinking fountains, by classroom sinks, or on concrete floors with leaks or frequent condensation) • Molds can be found almost anywhere; they can grow on virtually any substance, providing moisture is present. There are molds that can grow on wood, paper, carpet and foods.

26. Other Strategies • Humidity control • Control of relative humidity significantly reduces the bacteria and viruses • Maximum growth of viruses resulted at a relative humidity of 95% and above • Humidity range between 40% and 60% significantly reduces the risk to human health • Increased ventilation with filtration • Proper intake of air indoor and using effective air filtration systems significantly reduces the intake of Bioaerosols • Mechanical filters have been successful in removing the fungi and other microbial agents from the outdoor air

27. Other Strategies(contd.) • Available air filters • Coarse-fiber panel filters (efficiency – 10%) • Electrostatic precipitators (efficiency – 60% to 90%) • HEPA filters (efficiency – 90% to 100%) • Air cleaning • The air can be disinfected using various chemical compounds • Sodium hypochlorite • Hydroxy acids • Glycols

28. Criteria for choosing Chemical disinfectants • Lethal at low concentrations • Non-toxic and non-irritant to humans • Non-corrosive to metals and fabric • Should easily vaporize

29. Other preferred options • The most effective glycols are propylene and triethylene glycols • Desiccant air conditioning systems perform well in control of the Bioaerosols by: • Capturing the organisms • Killing them through severe desiccation