Sensor Systems for Biological Agent Attacks Protecting Buildings and Military Bases (2005) / Chapter Skim
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3 Indoor and Outdoor Bioaerosol Backgrounds and Sampling Strategies
3 Indoor and Outdoor Bioaerosol Backgrounds and Sampling Strategies
Pages 23-45
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From page 23... ...
, both indoor and outdoor bioaerosol backgrounds are considered, including current data on such aerosols, areas where critical data are lacking, and what approaches might be taken to provide the needed data. CurTent methods used for control of natural aerosols in buildings are discussed.
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pneumonias No cell wall in droplet nucleus Chlamydia One or more organisms 1-5 Chlamydia psitlasi in droplet nucleus Ridcettsia One or more organisms 1-5 Coxiella bumetii Obligate intracellular pathogen in droplet nucleus Bacteria One or more bacteria in 1-5 Micrococcus Vanable in size, shape, cell dnoplet nucleus or on a luteus wall composition raft Single or grouped dry 0.5-5 Bacillus census Highly Resistant endospores spores 3 Themmoactino myces Cell wall fragments <0.1 Algae One or more cells 5-10 Chlonococcus Chlonophyll, cellulose Nonvascular One or more spones 15-30 Mosses Chlorophyll, cellulose plants Vascular plants Spore 15-30 Lycopodium ferns Pollen 10-50 Trees, grasses, Sponopollenin weeds Pollen allergens ? Hairs 10-100 Cellulose Fragments ?
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From page 25... ...
fungal spores. The Burkard spore trap is another commonly used instrument for measuring pollen and spore concentrations.
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Pneumocystis caring is a nonculturable fungus that is responsible for much of the pneumonia in AIDS patients. It was predicted to be an airborne disease based on epidemiological theories and was only recently identified in air samples following development of DNA probes for analysis.
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Outdoor Pollen Pollen concentrations are seasonal and depend on the distribution and life cyde of source plants. Generally, there are three major pollen seasons: trees (spring)
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Weather strongly affects airborne pollen concentrations as well, with levels near zero during precipitation events. Pollen clouds can be transported for long distances.
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Seasonal prevalence patterns for outdoors as determined by pollen counts are probably indicative of both outdoor small-particle allergen prevalence and indoor levels of pollen and pollen allergens.'9 A number of studies have related rainfall and release of allergen from pollen grains.29 Data on relationships to asthma indicate either a long-delayed response to pollen exposure or release of allergen during rainfall.2' Measured allergen concentrations in Melbourne were 6 to 15 nanograms per cubic meter during the grass pollen season. Allergen peaks more or less parallel pollen peaks but tend to follow them (on a Manhour average basis)
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Clouds of Aspergillus fumigates spores (more than 1,000 per liter) and other spores are released from yard waste compost when the compost is disturbed.93 Spore Concentrations Several studies that document the broad range of spore concentrations that can be present in outdoor air are listed in Table 3.4.
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2000. Charactenstics of indoor and outdoor airborne fungi at suburban and urban homes in two seasons.
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Other Outdoor Bioaerosols Actual concentrations of viral particles in outdoor air are unknown. However, they have been recovered from plumes above sewage treatment facilities.39 Clearly, transmission of viral disease can occur via transport through outdoor air.
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Thn~eyearinvestigation of the natural airborne bacterial flu a at four localities in Sweden.
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Outdoor air; water Reservoirs (fountains, fish tanks) Outdoor air; dust; house plants Dust Dust, surfaces The animal; dust on surfaces, in carpeting, fumiture, clothing Outdoor air; surface growth; growth in materials and water Reservoirs; dust Growth in matenals, on surfaces Aenosolization Mechanism Cough, sneeze, other Respiratory Toilet flushing Bursting bubbles Surf action Cough, sneeze, other Respiratory Toilet flushing Action of humidifier Dnoplet splash; bubbling Dust disturbance Skin shedding activities; dust raising activities Human or animal activities; sweeping, vacuum Leaning; bellows action on sofl fumitune Disturbance of water; action of humidifiers, fountains, bubblers, etc.
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From page 35... ...
In Sweden, outdoor birch pollen peaks in May range from 80 to 140 grains per cubic meter, and indoor allergen concentration closely parallels outdoor pollen counts.47 Fahlbusch et al 43 measured 120 to 1 50 nanograms grass pollen allergen per square meter of carpet. Maximum levels ranged from 4,000 to 6,000 nanograms per square meter.
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From page 36... ...
However, this ratio is strongly dependent on the concentration of spores outdoors, with low outdoor spore counts often leading to ratios greater than 1 in the absence of active growth.5' Activities strongly influence concentrations of fungal spores in indoor air. Any activity that disturbs a source is likely to increase levels.
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2000. Charactenstics of indoor and outdoor airborne fungi at suburban and urban homes in two seasons Sci Total Envir 253.111-118 C
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Of rice building levels are usually relatively low (between 0.05 and 3 nanograms per liter) , with naturally ventilated building levels lower than levels in mechanically ventilated ones.5357 On the other hand, in areas where agricultural and animal confinement activities are occurring, levels are often much higher (e.g., 490 nanograms per cubic meter for swine confinement)
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From page 39... ...
In general, pollen and spore concentrations are expected to gradually rise in response to warmer temperatures and higher levels of CO2.3' Both pollen and fungal spores are produced in greater abundance as CO2 levels increase in their environment.32 Emberlin et al.33 evaluated long-term changes in pollen concentrations as possible causes for the increasing prevalence of hay fever symptoms. Land use changes, cumulative temperature, and rainfall were used as predictors for the severity of coming seasons in a single-equation multivariate model that resulted in greater th an 95 percent predictive value.
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From page 40... ...
.70 Another important set of pollen prediction parameters is endogenous to the plant. Consideration of possible pathogen effects is also importantly One group has used neural networks, chaos theory, and fractals to develop pollen predictive models.79 Spore models have also been ronstnucted, especially to predict prevalence of plant pathogens, which reach local concentrations in excess of 100 per liter.73 Factors intrinsic to the fungi (i.e., life cycle S
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From page 41... ...
This effect has not been carefully studied in ordinary buildings. While standard new HVAC filters can remove Considerable percentages of bacteria and fungi from outdoor air, wet, humid conditions may lead to bacterial growth and subsequent release into the building air.5' This effect has also been documented in a laboratory setbng.52 Cordoba, Spain in relation to meteorological parameters Int J
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and improvement in symptoms of hypersensitivity pneumonitis using electrostatic precipitators in the return duct of a home.93 Air Treatment Ultraviolet Light Ultraviolet light can damage or kill many microorganisms, although flhe kill rate is rarely 100 percent. Gram-negative bacteria are especially sensitive to ultraviolet light, while acid-fast organisms and spores are very resistant.94 A Combination of filtration and intensive ultraviolet light reduced bacterial aerosols by 90 to 92 percent, an insufficient reduction to protect fully from large bioagent releases95 but still providing a useful mitigation.
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From page 43... ...
Finding 3-2: Fungal aerosol plumes in outdoor air are likely to trigger false alamms in bioaerosol detectors, given the acute nature of the factors leading to massive releases. Fungal aerosols well in excess of 1,000 spores per liter have been documented, and with more accurate analysis, concentrations are likely to prove much higher.
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Recommendation 3-11 : The feasibility of using predictive models for bacterial and fungal aerosols to allow the development of algorithms that can normalize and differentiate the signal from these natural clouds from the bioaerosol detector signal should be studied.
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From page 45... ...
Some of these data may already be available in the plant pathology literature. Recommendation 3-12: A widespread outdoor air sampling network needs to be developed that will accumulate data for a wide variety of environments.
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