indoor air quality - uw courses web servercourses.washington.edu/envh557/class...
TRANSCRIPT
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Outline
• Indoor Air Quality – 1. Introduction & Health Effects – 2. HVAC – 3. Source of IAQ Problems & Contaminants – 4. Evaluation & Control
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Introduction
• Indoor air quality (IAQ) refers to the quality of 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 5 environmental risks to public health
• EPA studies indicate that indoor air levels of many pollutants may be 2-5 times, and occasionally, more than 100 times higher than 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 role in
IAQ problems • IAQ investigations often find no specific cause • Distinguish Sick building syndrome from indoor
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 AFTER
EXITING 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 industrial
settings – psychogenic components
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HEALTH EFFECTS
• Psychogenic illness – controversial – symptoms resulting from psychological or
psychosocial 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 code
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Section 2
Sources & contaminants
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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 to carboxyhemoglobin
• 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 or renovated 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 produce significant levels
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Contaminants
• Formaldehyde – health effects
• > 1-3ppm mucous membrane irritation, respiratory symptoms
• 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 bioaerosol exposures
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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 water
contaminated 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 and
AC 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 in humidifiers 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 5-20,000
people die annually of lung cancer from radon exposure
– 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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Section 3
HVAC & Building Systems
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HVAC Systems
• Purpose: – thermal comfort – mix and distribute adequate amounts of
outdoor air – isolate & remove odors and contaminants
through pressure control, filtration & exhaust fans
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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 • Physical activity levels • clothing • physiology
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HVAC System ASHRAE standard 55-1981
RH WinterTemp (°F)
SummerTemp (°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 or
cooled, 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 per occupant
– 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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Section 4
Evaluation and control
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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 °F T return air - T mixed air
T return air - T outdoor air x 100
return air - in return air system before the mixing chamber mixed air - upstream of heating/cooling unit - before the fan outdoor 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 handler return air - in return air system before the mixing chamber outdoor air - outdoor air
% OA =
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Evaluation
• Converting %OA to CFM/person
Outdoor air (%) x total airflow (cfm)
# of building occupants OA (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 53776577% =
−
−= xOA
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Evaluation
• Indirect methods for contaminants – carbon dioxide levels
• CO2 is an indicator of adequate/inadequate ventilation
• levels exceeding 800 ppm are often associated with occupant 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 know what 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 for Health Professionals.
EPA (1991). Building Air Quality: A Guide for Building Owners and Facility Managers
Available at: http://www.cdc.gov/niosh/pdfs/iaq.pdf
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END HERE