•indoor air qualitycourses.washington.edu/envh557/protected/2006/557_hvac... · 2006-01-17 ·...
TRANSCRIPT
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Outline
• Indoor Air Quality– Introduction
– Health Effects
– HVAC
– Source of IAQ Problems
– Contaminants
– Evaluation & Control
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Introduction
• Indoor air quality (IAQ) refers to the qualityof air in:– offices
– schools
– homes
– health care settings
– settings other than industrial
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Introduction
• EPA ranks indoor air pollution in the top 5environmental risks to public health
• EPA studies indicate that indoor air levelsof many pollutants may be 2-5 times, andoccasionally, more than 100 times higherthan outdoor levels
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Introduction
• IAQ is an ongoing concern for urban workforce
• approximately 90% of time spent indoors
• energy conservation efforts in 70’s play a rolein IAQ problems
• IAQ investigations often find no specific cause
• Distinguish Sick building syndrome fromindoor related illiness
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Introduction
• Standards/Guidelines– OSHA proposed an IAQ standard in 1994 -
put on the shelf– ASHRAE has guidelines for ventilation specs– EPA/NIOSH has Building Air Quality Action
Plan– EPA has developed report “Healthy Building -
Healthy People”
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HEALTH EFFECTS
SICK BUILDING SYNDROME (SBS)VS
BUILDING RELATED ILLNESS (BRI)
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HEALTH EFFECTS
• SICK BUILDING SYNDROME– A PERSISTENT SET OF SYMPTOMS IN > 20%
– CAUSE(S) NOT USUALLY RECOGNIZABLE
– COMPLAINTS/SYMPTOMS RELIEVED AFTEREXITING BUILDING
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HEALTH EFFECTS
• SICK BUILDING SYNDROME (SBS)
– EYE, NOSE, OR THROAT IRRITATION
– HEADACHES
– FATIGUE
– REDUCED MENTATION
– IRRITABILITY
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HEALTH EFFECTS
• SICK BUILDING SYNDROME (SBS)
– DRY SKIN
– NASAL CONGESTION
– DIFFICULTY BREATHING
– NOSE BLEEDS
– NAUSEA
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HEALTH EFFECTS
• BUILDING RELATED ILLNESS
– CLINICALLY RECOGNIZED DISEASE(S)
– EXPOSURE TO INDOOR AIR POLLUTANTS
– RECOGNIZABLE CAUSES
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HEALTH EFFECTS
• BUILDING RELATED ILLNESS (BRI)
– PONTIAC FEVER - LEGIONELLA spp.
– LEGIONNAIRE’S DISEASE
– HYPERSENSITIVITY PNEUMONITIS
– HUMIDIFIER FEVER
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HEALTH EFFECTS
• BUILDING RELATED ILLNESS (BRI)
– ASTHMA
– ALLERGY
– RESPIRATORY DISEASE• CHRONIC OBSTRUCTIVE PULMONARY
DISEASE (COPD)
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HEALTH EFFECTS
• IAQ can be a complex issue:– numerous sources
– often there is no point source as in industrialsettings
– psychogenic components
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HEALTH EFFECTS
• Psychogenic illness– controversial
– symptoms resulting from psychological orpsychosocial origin
• stressors
• suggestions from co-workers
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HEALTH EFFECTS
• Mass psychogenic illness components– Poor work environments
– Labor/management problems
– Persistence of complaints following removal of“offending components”
– Excessive work loads
– Boring and repetitive work
– Gender-specific complaint rates
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HEALTH EFFECTS
• Multiple chemical sensitivity– Even more controversial!
– Other names for the syndrome:• Environmental illness, ecologic illness, allergic toxemia,
cerebral allergy
– Assertions:• failure to adapt to low-dose exposure to man-made
chemicals resulted in sensitivity to these chemicals
• Immune system becomes “overloaded”
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HEALTH EFFECTS
• Multiple chemical sensitivity– Vague symptoms: depression, irritability, mood swings,
fatigue, drowsiness, respiratory symptoms, etc.
– Possible triggers: organics, perfumes, building materials,paints, exhaust, smoke, etc.
• Opponents to MCS– No scientifically plausible mechanism
– No diagnostic tests have been substantiated
– MCS has not been clearly defined• No ICD-9 code
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HVAC System
• Purpose:– thermal comfort
– mix and distribute adequate amounts ofoutdoor air
– isolate & remove odors and contaminantsthrough pressure control, filtration & exhaustfans
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HVAC System
• Components:– furnaces & boilers
– chillers
– cooling towers
– air handling units
– exhaust fans
– ductwork
– filters
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HVAC System
• Thermal comfort– factors:
• relative humidity
• air movement
• activity level
• clothing
• physiology
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HVAC SystemASHRAE standard 55-1981
RH Winter
Temp (°F)
Summer
Temp (°F)
30% 68.5 – 76.0 74.0 – 80.0
40% 68.5 – 75.5 73.5 – 79.5
50% 68.5 – 74.5 73.0 – 79.0
60% 68.0 – 74.0 72.5 – 78.0
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HVAC System
• Ventilation to meet occupant needs– most air handling units distribute a blend of
outdoor air with recirculated indoor air
– conditioned air is a blend that is heated orcooled, filtered and sometimes humidified
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HVAC System
• ASHRAE std. 62-1999– For a typical office space
• 15-20 cubic feet per minute (cfm) of outside air peroccupant
– 15 CFM for reception areas
– 20 CFM for office space & conference rooms
– 60 CFM for smoking rooms
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HVAC Systems
• Control of odors & contaminants– in office buildings - dilution
– ventilation efficiency• the ability of the ventilation system to distribute
supply air and remove odors and pollutants
– local exhaust ventilation• isolate and remove contaminant at the source
– fume hoods
– kitchen range hood exhaust
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HVAC
• Control of odors & contaminants– isolation - controlling pressure relationships
between rooms• positive pressure
– more air is supplied than is exhausted
• negative pressure– less air supplied than is exhausted
– used in “mixed use” buildings
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Sources of IAQ Problems
• Outside Building– contaminated outdoor air
– emissions from nearby sources
– moisture or standing water
– Soil gas
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Sources of IAQ Problems• Equipment
– HVAC system• dust or dirt in ductwork & other components
• microbial growth in drip pans, humidifiers, coils &water spray systems
• refrigerant leaks
– Non-HVAC equipment• office equipment
– VOC’s (solvents, toner, cleaners)
– ozone from copier
• emissions from shops, labs, cleaning processes
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Sources of IAQ Problems
• Building materials / indoor sources– chemicals released from materials
• formaldehyde from adhesives, particle board• other VOCs from carpeting & adhesives
– microbial contamination• Water-damaged carpeting, ceiling tile, furniture,
etc.
– dust or fibers• friable asbestos• old or deteriorated furnishings
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Source of IAQ Problems
• Human activities– Housekeeping– Maintenance– Smoking– Too many people
• Miscellaneous– chemical spills– flooding– fire damage– redecorating & remodeling activities
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Classes of Contaminants
• Combustion products
• VOCs
• Bioaerosols
• Particulates (non-viable)
• Radon
• Environmental tobacco smoke
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IAQ Problems
• NIOSH Study found:– 52% - poor ventilation
– 17% - indoor pollutants
– Unknown – 12%
– Outside Pollutants – 11%
– Microbiological – 5%
– Furnishings – 3%
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Contaminants
• Combustion products– Types
• carbon monoxide
• nitrogen oxide
• sulfur dioxide
– Sources:• boilers
• kerosene space heaters
• generators
• trucks & cars (re-entrainment)
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Contaminants
• Carbon monoxide– health effects
• asphyxiant which converts hemoglobin tocarboxyhemoglobin
• symptoms:– fatigue, SOB, headache, nausea, death at high levels
• standard: TLV-TWA = 25 ppm
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Contaminants
• Oxides of nitrogen– Respiratory irritant (lower tract)
• Low water solubility
– in susceptible individuals• decreased lung function
• exacerbation of asthma
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Contaminants
• Sulfur dioxide– Eye & upper respiratory tract irritant
• higher water solubility
– in susceptible individuals• decreased lung function
• exacerbation of asthma
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Contaminants
• VOCs– types:
• aliphatic hydrocarbons• halogenated hydrocarbons• aromatics• alcohols• ketones & esters
– can be a problem in new buildings orrenovated areas
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Contaminants
• Formaldehyde– used in numerous building materials
• bonding/laminating agents
• adhesives
• paper/textiles
• foam insulation (urea foam)
– off-gassing of new materials can producesignificant levels
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Contaminants
• Formaldehyde– health effects
• > 1-3ppm mucous membrane irritation, respiratorysymptoms
• chronic exposures may increase risk of cancer
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Contaminants
• Bioaerosols• airborne particles that are living organisms or once
living organisms
• fungi
• bacteria
• virus
• endotoxins (outer membrane of gram-)
• protozoa
• mites
• pollen, spores, mycotoxins, etc.
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Contaminants
• Basic concepts of bioaerosol exposure– reservoir
– amplification
– dissemination
• no applicable regs for bioaerosolexposures
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Guidelines, etc.
• Resources/Guidelines– http://www.aiha.org/GovernmentAffairs-
PR/html/prmoldsources.htm
• Legislation– Toxic Mold Safety & Protection Act (6/02)
– http://www.house.gov/conyers/mold.htm
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Contaminants
• Legionnaire’s disease• caused by Legionella pneumophilia
• mild to severe pneumonia exposure to watercontaminated with bacterium
– Elderly & immunosuppressed most susceptible
• symptoms:– fever, cough, SOB
– fatigue, headache
– chest pain
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Contaminants
• Hypersensitivity pneumonitis– allergic reaction from exposure to airborne
antigens
– Often traced to contaminated humidifiers andAC systems
– symptoms include:• acute & recurrent pneumonia
• cough, SOB, fatigue, fever
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Contaminants
• Humidifier fever (self-limiting)– respiratory illness caused by exposure to
endotoxins from microorganisms found inhumidifiers and air conditioners.
– symptoms:• fever, chills, muscle aches and malaise• chest tightness/breathlessness on exertion.
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Contaminants
• Non-viable particulates– particulates from combustion sources
– fibers such as asbestos
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Contaminants
• Radon– natural breakdown product from radioactive
decay of uranium-238
– EPA estimates approximately 5-20,000people die annually of lung cancer from radonexposure
– found in rocks & soils with granite, shale,phosphate & pitchblend
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Contaminants
• Radon– EPA guidelines:
• acceptable: <4 pCi/L
• above avg: 4 - 20 pCi/L
• greatly above avg: 20 - 200 pCi/L
• grave level: > 200 pCi/L
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Contaminants
• Radon– source of entry into homes
• soil gas– cracks in foundation
– cracks in basement flooring
– loose-fitting pipes
• building materials - granite
• water
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Contaminants
• Reducing levels:– sealing points of entry
– basement ventilation
– sub-slab depressurization
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IAQ Evaluation
• Initial walkthrough• Workplace inspection• Worker Interview• Estimating Outdoor Air Quantities
– Thermal balance– Carbon dioxide balance
• Measuring airborne contaminants– indirect– direct
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Initial Walkthrough/Inspection
– contact building manager– identify types, affected workers & areas of
complaints– Identify HVAC zones, maintenance schedules– Identify recent renovations/design changes– identify potential sources of contaminants
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Inspection
• Check the following elements:– Temperature
– Humidity levels
– Odors
– Carbon dioxide levels
– HVAC initial inspection
– other
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Worker Interview
• Worker interview(s)– description & temporality of symptoms– description & temporality of any odors– work activities & materials– possible causes?– Any other employees with symptoms?
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Further Evaluation
• Collect additional info:– Worker surveys
– HVAC system (s)
– Pollutant pathways & sources
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Evaluation
• Worker survey– description of symptoms
– temporality of symptoms
– work activities & materials
– description & temporality of any odors
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Evaluation
• Thermal mass balance
T = temperature in °FT return air - T mixed air
T return air - T outdoor air
x 100
return air - in return air system before the mixing chambermixed air - upstream of heating/cooling unit - before the fanoutdoor air - local outdoor temperature near air handling intake
% OA =
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Evaluation
• Carbon dioxide measurements
C supply air - C return air
C outdoor air - C return air
x 100
C = carbon dioxide in ppm
supply air - in room or in air handlerreturn air - in return air system before the mixing chamberoutdoor air - outdoor air
% OA =
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Evaluation
• Converting %OA to CFM/person
Outdoor air (%) x total airflow (cfm)
# of building occupantsOA (cfm)/person =
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Example
Thermal Mass Balance Approach:– TOA = 53oF
– TMA = 65oF
– TRA = 77oF
– 250 occupants in building
– HVAC CFM = 10,000
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Example
Answer:
20250
0.5 x 10,000 OA/person CFM ==
50% %100 5377
6577% =
−
−= xOA
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Evaluation
• Indirect methods for contaminants– carbon dioxide levels
• CO2 is an indicator of adequate/inadequateventilation
• levels exceeding 800 ppm are often associated withoccupant complaints
• can be measured with:– colorimetric detector tubes– electrochemical detectors– IR
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Evaluation
• Total hydrocarbons:– levels exceeding 5 mg/m3 tend to be
associated with IAQ complaints
• Levels of bioaerosols– sample, identify & quantify biological agents
– No widespread standards exist
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Evaluation
• Perform air sampling only if you knowwhat you are looking for– direct-reading instruments
– air sampling & collection
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Control
• HVAC maintenance & operation• maintenance of equipment and building
materials• remove materials that become damp• remove or remediate contaminant source• follow-up on worker complaints
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Sources of information
Building Managers Guide to IAQ:http://www.epa.gov/iaq/largebldgs/baq_page.htm
IAQ Building Education and Assessment Model
(I-BEAM) Computer Software: http://www.epa.gov/iaq/largebldgs/ibeam_page.htm
EPA Indoor Air Quality: Tools for Schools:http://www.epa.gov/iaq/schools/index.html
IAQ Clearinghouse:http://www.epa.gov/iaq/iaqinfo.html
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References
EPA (1994). Indoor Air Pollution: A guide forHealth Professionals
EPA (1991). Building Air Quality: A Guide forBuilding Owners and Facility Managers
Available at: http://www.cdc.gov/niosh/pdfs/iaq.pdf