Transcript Bioaerosols & Indoor Air Quality

Bioaerosols &
Indoor Air Quality
EMD545b
Lecture #8
Bioaerosol
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Mixture of solid or liquid particles in air
containing whole or parts of biological
materials.
Biological materials include human
pathogens, toxic or allergic pieces of
microorganisms, dust mite parts or
feces, animal dander, fur, dried saliva,
and animal waste products
Bioaersols (Examples)
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Human pathogens
– fungi, bacteria, parasites, viruses
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Endotoxin (LPS from gm neg.
bacteria)
Mites, animal dander (other allergens)
Fungi
– mold
– spores
– mycotoxins
Sick Building Syndrome (SBS)
Sick Building Syndrome (SBS)
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Acute health and comfort effects
experienced by building occupants that
are apparently linked to time spent in
the building. (EPA)
No specific illness identified
symptoms appear 2-6 hours after entry
symptoms disappear shortly after
leaving or overnight (fresh air)
Symptoms of SBS
– headache
– fatigue
– shortness of breath
– sinus congestion
– cough
– sneezing
– eye, nose, and throat irritation
– skin irritation
– dizziness, nausea
Building Related Illness (BRI)
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Illness brought on by exposure to
building air.
Symptoms of diagnosable illness
identified.
Linked to agents in the air
Examples (Legionnaire’s Disease,
Pontiac Fever, Humidifier Fever,
Hypersensitivity)
Hypersensitivity Diseases
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Antigens stimulate antibody response
– Hypersensitivity Pneumonitis (IgG
produced, Farmer’s Lung)
– chills, fever, cough, shortness of breath (48 hours post exposure)
Humidifier Fever
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Flu-like symptoms (4 - 8 hours postexposure)
no prominent respiratory symptoms
symptoms dissipate w/in 24 hours
related to cold-aerosol humidifiers in an
enclosed space
• empty water daily, disinfect after use
Allergic Rhinitis
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Hay fever
– nasal obstruction, discharge, post-nasal
drip
– sneezing, itching, tearing eyes
– cough
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pollen, mold spores, dust, dander
Asthma
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Triggers at work
– pollen
– mites
– fungi
– insects/arthropods
Allergens
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Dust mites
Cats, dogs (pets)
Dander (animal facilities)
Cockroaches
Pollen
Susceptible Building Occupants
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Allergies, asthma
Respiratory disease
Immunosuppressed (patients)
Contact lens wearers
Others?
Infectious Diseases
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Legionnaire’s Disease
– Legionella bacterium
• growth in water sources 68 - 120 F
• associated with algae
• cooling towers, evaporative condensers, spas,
plumbing systems, humidifiers
– severe pneumonia (5 - 30% mortality)
• immunosuppressed, those with respiratory
conditions at much higher risk
– 1976 outbreak at American Legion
Convention
• 182 cases, 29 deaths
– 10,000+ US cases estimated annually
Psittacosis
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Chlamydia psittaci (bacterium)
– fever, chills, headache, muscle aches, fry
cough
– pneumonia
– infection of other organs, can be fatal
– < 50 cases/year in US
– inhalation of dried secretions from infected
birds
Aspergillosis
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Pneumonia related to inhalation of
Aspergillus spores
– with fever, cough, chest pain
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opportunistic infection in immune
suppressed and those with lung disease
– Aspergillus fumigatus, A. flavus most
common causes
– important nosocomial infection
– release during construction/renovation
work
Other Fungal Pathogens
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Cryptococcus
– Cryptococcus neoformans
– isolated from soil worldwide (bird droppings
- pigeons)
– inhalation of spores
– 85% of infections among immune deficient
– meningitis, permanent neurological
damage
– 12% mortality rate
Other Fungal Pathogens
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Histoplasmosis
– Histoplasma capsulatum
– flu-like illness in most (pulmonary
involvement of disseminated infection in
severe cases)
– contaminated soil (bird or bat droppings)
– inhalation of spores
– immunocompromised at high risk
Mycotoxins
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Over 200 known
Inhalation, ingestion, skin contact
Aflatoxin B1 (liver cancer, lung cancer?)
Trichothecen mycotoxins
– T-2 (inhibits RNA and protein synthesis,
toxic to dividing cells, damages variety of
organs, tissues, immunosuppressive)
– Yellow rain (russian military 1975 - 1981)
Fungal Wall Cell Components
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Beta (1 - 3) - D- Glucans
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small cell wall pieces
inflammatory lung and airway reactions
impair immune system
flu-like illness from high exposures (Organic Dust
Toxic Syndrome)
Building Assessment
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Building History
– date of construction
– renovations, upgrades
• new furnishings
– meet with building management
– list of building activities
– previous floods, water damage, leaks
Energy Efficient Buildings
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1970’s - Arab oil embargo
construction of “tight” buildings
less use of fresh outdoor air, more recirculation of treated air
40% energy cost savings
99% of requests to NIOSH for air quality
investigations occur after 1978
Building Assessment
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Review of occupant complaints
– building location, number of reports
– time of complaints (daily or seasonal
pattern)
– type of complaint
• health symptoms (acute/chronic)
• comfort (thermal, odor, noise, lighting)
• NIOSH 80% rule
– input from healthcare professional(s)
Building Assessment
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Building walkthrough
– with building manager
– with some occupants (union
representation)
– complaint areas and non-complaint areas
– housekeeping
– visible fungal growth (sources of moisture)
– overcrowding
– fans, blocked diffusers, heaters, humidifiers
Hidden Sources of Mold
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back side of drywall
top of ceiling tiles (roof leaks)
underside of carpets (carpet below filing
cabinets)
pipe chases, utility tunnels
elevator shafts (building syringe)
drain pans in HVAC system
insulation within ductwork
Building Assessment
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Monitor CO2, dust
Temperature, %RH
Smoke test (airflow)
Amount of fresh air
ASHRAE 62-1999
– 20 CFM/person
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Odors (volatile
chemicals in air)
Building
Assessment
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Review HVAC system
– type of system
– plenum or ducted
system
• insulation in ductwork?
– dirty mechanical room?
– preventive
maintenance?
– % of re-circulated air
– time HVAC turned
on/off
– blocked airflow
– odors, stagnant water?
– biocides in system?
Building HVAC System
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Outdoor Air Intake
– location (downstream of…)
– work in vicinity
– pollutants in vicinity
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bird droppings, decaying matter
vehicles, fuel-powered equipment
exhaust stacks, toilet exhaust stacks
cooling towers, puddles, garbage, etc.
– Screens, filters, BIOSECURITY!
• Air intakes can be used for terrorism events
Building HVAC System
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Air filtration
– filter location
– % efficiency
– pre-filters?
– Maintenance schedule (changes)?
– Appearance (excessive dirt/debris)
– Fit (leaks around filters - bypass system)
Building HVAC System
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Supply fan
– percentage of fresh air
– supply diffusers in rooms (dirt/debris)
– air patterns within room (location of supply
and exhaust diffusers)
• short circuiting of air?
• Poor mixing?
Building HVAC System
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Heating/cooling coils
– condensation drip pans
– stagnant water (blocked drains)
– sloped toward drain
– biocides in use?
Building HVAC System
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Humidification system
– cold water humidification
• potable, drained off well
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Exhaust Fan (discharge from building)
– normal, hazard, toilet (separate)
– 50 ft from supply intakes
– at height and velocity to remove from
building
– no discharge out side of building
Bioaerosol Sampling
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Develop hypothesis (plan)
Find source and remediate
Sample to assess building, confirm
findings
assess occupant exposures
Bioaerosol Sampling
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Select sampling locations (numbers of
samples)
– complaint areas, non-complaint areas,
outdoors, time of day, year
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Sampling method?
– Contact (direct microscopic examination)
– bulk (bag pieces of suspect material,
water)
– swab (swipes of suspect surfaces)
– air (viable, non-viable methods)
Bioaerosol Sampling
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Air sampling
– non-viable methods (spore traps, filter
cassettes)
• Air-O-Cell
– viable methods
• AGI-30 (all glass impinger - air pumped through
liquid medium - good for bacteria)
• sieve impactors (Anderson Sampler, RCS)
• Flow rates, calibration critical
Bioaerosol Sampling
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Select Environmental Microbiology
Laboratory
• accreditation/certification, selection of media
• incubation temperature for samples?
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Sampling Media
– viruses, bacteria, parasites, mites,
endotoxins
• TSA, blood agar for bacteria
– fungi
• psychrophyllic, mesophyllic, thermophyllic
• nutrient requirements (wet, normal conditions)
• DG-18 (wet), MEA (general)
Bioaerosol Sampling
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Collection/Transport Protocols
– instrument calibration
– sterility of media, containers, swabs
– disinfection between each use
– chain of custody forms
– identification of samples
• field blank, control blank, coded samples
– prompt shipment/delivery to lab
• bacteria samples on ice
Bioaerosol Sampling
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Enumeration of data
– quantity per ml, gm, liter of air, m3 of air,
square cm, m2 of surface
– quantity of organisms numerator
– quantity of media sampled denominator
• time (min.) x flow rate/min. = total volume
• (1000 liters per m3 of air)
Bioaerosol Sampling
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Analysis of data (only snapshot in time)
– identification of genus and species
– concentration of each per location sampled
– rank order indoors vs. outdoors
– indoor to outdoor ratio
• low yield outdoors in colder months
– complaint vs. non-complaint areas
– immediate notification from lab of serious
results
– pathogens, positive anthrax, elevated levels in
hospitals
Standards and Guidelines for
Fungi in Indoor Air
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No Standards!
» Yet
• too many variables (personal susceptibility and variation
among individuals - what levels for sensitized?)
» paradichlrobenzene example at Peabody Museum
» latex allergy in BWH OR
• Standards = must
• Guidelines = should
Standards and Guidelines for
Fungi in Indoor Air (Rao et al)
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Comprehensive review of literature
ACGIH
– <100 CFU/m3 = low
– 100 - 1000 CFU/m3 = intermediate
– >1000 CFU/m3 = high
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AIHA
– >1000 CFU/m3 atypical
Standards and Guidelines for
Fungi in Indoor Air
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General statements
– levels indoors should compare with levels
outdoors
– pathogenic organisms not acceptable in
indoor air (WHO, Canada, AIHA)
– indoor:outdoor > 1 may (investigate
potential indoor source)
Remediation
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Water = problem!
– remove water, dry, clean, disinfect
– completely remove mold and dry waterdamaged areas
– address the source of water or humidity
problem
– Options
• discard and replace, wet vacuum, drying (if
<24-48 hours), dehumidification, freezing,
Remediation
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Cleaning can disperse contaminants
– don’t sweep, vacuum w/out filtration
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damp mop, disinfectant wipe (wet
collection methods)
HEPA filtered vacuum cleaners
Containment during Remediation or
Construction in Sensitive Areas
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Sample before project (baseline for clean and
contaminated areas)
Communicate to personnel in adjacent areas
– scope of work
– potential hazards
– control measures
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Ongoing sampling during project
Final clearance samples (to baseline of clean
areas)
Containment during Remediation or
Construction in Sensitive Areas
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Schedule work after hours (evenings,
weekends)
Consider closing facility if very sensitive
population within/nearby
– YPB Medical Oncology
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Hire/assign objective, independent project
monitors
– ensures all workers adhere to protocol
– reports problems, breaches immediately
– can shut job down on site if necessary
Containment during Remediation or
Construction in Sensitive Areas
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Containment barriers
– solid gypsum barriers built (temporary
construction)
– polyethylene sheeting
– anteroom for clothes change
– HEPA filtered exhaust fan in contaminated zone
• create negative pressure gradient within space
• exhaust only purified air out of space
Containment during Remediation or
Construction in Sensitive Areas
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Personal Protective Equipment
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Full jump suits, booties, hood
PAPR or N-100 Disposable respirator or higher
Full face shield (cover all exposed skin)
Tape wrists ankles, etc
Spray contaminated areas with disinfectant
before removal
– suppress aerosols
– decontaminate mold
Containment during Remediation or
Construction in Sensitive Areas
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Collect and seal waste in bags
decontaminate exterior of waste bags
transport out of space in covered cart
(exterior also decontaminated)
HEPA vacuum all surfaces after each shift
Disinfect surfaces after shift
Remove and bag PPE after each exit
– YPB pizza party
Containment during Remediation or
Construction in Sensitive Areas
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Extensive clearance samples taken
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Keep area closed until clearance samples
verified clean (below acceptable set point and
absence of pathogenic organisms)
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Don’t forget to get sanity back after project!