practical aspects of indoor air exposure assessment for ... · school of public health objectives...

Robert J. Laumbach M.D., M.P.H., C.I.H.

Associate Professor

Environmental and Occupational Health

MARCOEM October 6, 2018

Practical Aspects of Indoor Air Exposure

Assessment for Occupational Physicians

School of Public Health

Objectives

Conduct a differential etiology for common medical

complaints and diagnoses that may be related to indoor

environmental factors

Develop testable hypotheses for causes of building-

related illness.

Comprehend and apply indoor environmental assessment

reports to assist patients and/or health teams to solve

problems

Recommend controls for common indoor environmental

hazards.


Scope and Emphasis

• Practical approaches

• Focus on Indoor Air Quality (IAQ)

• Problems encountered in our consultation practice at the

Clinical Center at the Environmental and Occupational Health

Sciences Institute (EOHSI)

• Focus on industrialized and post-industrial issues


Settings

• Office

• School

• Public buildings

• Home

• Trains, planes, and automobiles

• NOT industrial environments

• The setting often determines expectations for environmental

quality


Indoor Air Quality and Health

• An ancient problem

• A growing issue over the past several decades

• Newer and emerging issues

– Green buildings and occupant health

– Microbial communities and occupant microbiomes

– PDBEs, phthalates, etc.

– Chinese wallboard, mercury in rubberized gym floors, etc.

• A challenging area, especially for Occupational Medicine

– Diverse potential exposures

– Few exposure standards

– Individual host sensitivity

– Often non-specific symptoms that are difficult to explain

– Psychosocial factors


Many indoor environmental agents

• Physical, chemical, biological, ergonomic, social

• Many sources

– Indoors or outdoors

– Materials

• Construction

• Furnishings

• Cleaning compounds

• Personal care products

– Building systems

• Heating ventilation and air conditioning (HVAC)

– Activities

• Construction

• Modifications

• Cleaning

• Cooking


Many potential diseases, conditions, and

symptoms

• Health

• Productivity

• Happiness and satisfaction (well-being)


Illness and disease

• Building-related illness

– Disease

– Non-specific building-related illness

• Sick building syndrome

• Individual chemical sensitivities


Classification of contaminants: by effects

• Acute and often symptomatic

– Irritants

– Sensitizers

– Rarely specific target-organ toxicants (CO, CFCs, high level VOCs)

• Chronic and long-term risk

– Carcinogens: e.g. asbestos, radon, formaldehyde

– Sensitizers

– ? Endocrine disrupting compounds

– ? Specific target organ effects: reproductive, immune system

Often, no specific agent can be identified, but

interventions to improve air quality are still effective


General classes of agents

• Combustion byproducts

• Volatile organic compounds (VOCs)

• Bioaerosols


Combustion products (indoor and outdoor sources)

• CO

• Nitrogen dioxide (NO2)

• Particulate matter (PM)

• Environmental tobacco smoke


Carbon monoxide

• Incomplete combustion product

• Often from unvented or poorly-vented sources

– Furnaces

– Hot water heaters

– Internal combustion engines: cars

• Measure with real-time instruments: WHO indoor standards

• Control

– Maintenance

– CO alarms

Carbon Monoxide Level Alarm Response Time

40 PPM 10 hours

50 PPM 8 hours

70 PPM 1 to 4 hours

150 PPM 10 to 50 minutes

400 PPM 4 to 15 minutes


Nitrogen dioxide (NO2)

• Very hot flames oxidize N2 in the air

• Unvented gas flames, especially stove tops

• Internal combustion engines

– Indoor and outdoor sources

• Measurement with real-time instruments or sorbent samplers.

• WHO indoor standards similar to EPA outdoor standards (53

ppb annual, 100 ppb 1-hr)


Particulate matter

• Combustion sources inside and outside

• Mostly fine PM2.5 (less than 2.5 microns in diameter)

• Stove tops

• Fireplaces

• Environmental tobacco smoke

• Candles

• Incense

• Real-time particle counters, nephelometers

• EPA outdoor standards: PM2.5 35 µg/m3 24-hr, 12 µg/m3

annual


VOCs

• Formaldehyde in building materials, furniture, adhesives

• Solvents

• Paint

• Cleaning products

• Personal care products

• Infiltration from outside

• Vapor intrusion


Bioaerosols

• Mold

• Bacteria

– Legionella

– Non-Tuberculous mycobacterium

• Viruses

• Rodent antigens

• Pollen

• Dust mites

• Cockroach feces

• Pet allergens


Industrial Hygiene Approach

• Anticipation

• Recognition

• Evaluation

• Control

• Public Health Approach:

• Primary, secondary, and tertiary prevention


Anticipation and recognition

• Prevention

• Common issues

– Inadequate ventilation

– Chemical contaminants

• Various irritants: VOCs, dust

• Formaldehyde

– Bioaerosols (Mold)



• Design and build quality

• Procurement

• Importance of employee-management relationships and trust



• Buildings are complex systems

• Structure

• Contents

• Activities

• Operations

• Maintenance

• Individual occupant sensitivities

• Social structure

• Requires a case-by-case approach to preventing and

addressing problems


Ventilation

• Passive ventilation or active mechanical ventilation?

• Dilutes air contaminants from indoor sources

• Delivers air contaminants from outdoor sources

• May include filtration of indoor and outdoor source pollutants


Ventilation control

• Local exhaust ventilation; e.g. hood over a stove

• General, dilution ventilation

• Isolate areas with sources

• Maintain positive pressure to keep contaminants out

• Filtration: efficiency vs. effectiveness

• Rule of thumb:

– For outdoor sources: reduce fresh air ventilation and/or remove

contaminant from intake air

– For indoor sources: increase fresh air ventilation and/or remove

contaminant from room air.


IAQ should be part of an overall building

management plan

• See EPA and other sources

– Building Air Quality Guide: A Guide for Building Owners and Facility

Managers (EPA)

• https://www.epa.gov/indoor-air-quality-iaq/building-air-quality-guide-guide-

building-owners-and-facility-managers

https://www.epa.gov/indoor-air-quality-iaq/building-air-quality-guide-guide-building-owners-and-facility-managers


Responding to complaints:Diagnosing IAQ Problems

• Identify the problem and causative and associated factors

• Act to correct the problem and prevent recurrence

• Avoid causing other problems


Four basic factors influencing IAQ

• Contaminant sources

• Exposure pathways

– HVAC system

• Occupants

– Not just passive “receptors”: symptoms, observations, actions


Usual steps in IAQ assessment

• Initial assessment

– Walkthrough inspection

– In-house or consultant

• Develop and test hypotheses

– Test by additional observation, e.g. measurements of concentrations, air flow

– Test by intervention: changing building conditions

• Overall common-sense approach

– Identifiable odor; look for sources

– Generalized symptoms of malaise, fatigue, headaches, and other

symptoms: rule out pollutant sources, check ventilation, modify as

needed

– Limited to a specific location; look for pathways to that location

– Consider non-IAQ factors; social, psychosocial

Initial Assessment• Talk with occupants• Walk-through

Do you have an

explanation?

Collect Additional Information• Building occupants• HVAC system• Pollutant pathways• Pollutant sourcesDevelop hypotheses

Test hypothesis by changing building

conditions or appropriate testing

Do results support

hypothesis?

Attempt a control strategy

Follow-up Validation

Yes

No

No

Yes Solved?

No

Yes

Conducting an IAQ

Investigation: Flow chart(Modified from USEPA 2014)


Gathering more information

• Employee interviews or survey questionnaire

• Examination of building HVAC system

– Capabilities / specifications

– Maintenance

• If no apparent explanation, basic measurements such as CO2,

T and RH may be helpful

• Directed measurements test hypotheses: air flow, moisture,

specific contaminants (e.g. CO, formaldehyde, other

hypothesized VOCs), mold on surfaces and/or airborne


More on MOLD

• Challenging

– Living organism / community

– Mold spores are ubiquitous

– No established standards for indoor mold

– Alarming reports about “toxic mold”

– Claims of many symptoms/conditions/diseases attributed to mold

• Consensus: mold should not be proliferating in occupied

spaces

– Potential health effects

– Structural damage

– Aesthetics


Mold: biological pathways to illness

• Odor

– The “yuck factor,” disgust

• Irritation

– MVOCs?

– Spore components?

• Hypersensitivity

– Allergic rhinitis

– Allergic asthma

– Hypersensitivity pneumonitis

• Colonization or Infection

– Rare; usually host with some form of compromised immunity

• Mycotoxins?

Molds Indoors

• Amplification

– Food, usually cellulose

– Free water

• Spore release varies:

– diurnal variation

– humidity

• Chemical products:

– allergens

– volatile organic compounds (VOCs)

– mycotoxins

• Airborne hyphal fragments


Source: Molds (filamentous fungi)

facstaff.cbu.eduPenicillium

Aspergillus


Sometimes the source of mold is obvious….

http://www.whentechfails.com/toxic-mold-floodings-evil-twin/


Hypothesis-driven investigation approach for mold

(aspirational)

• Inspection

• Narrative report

• Hypotheses stated

• Initial low-cost measurements, e.g. T/RH, moisture

• Clearly-stated purpose of sampling of air, surfaces, sources

• Circumspect interpretation including limitations


Assessing exposure to mold

• If visible and circumstantial evidence (moisture, porous

organic material), then generally no testing is needed

– Photographic evidence may be helpful

– Moisture meter measurements may be supportive

• Tape lift, or culture of swab or destructive samples, can

document for medical-legal purposes

• Air sampling, if needed, to document exposure pathway

• Can link surface and air samples by species distribution


Spore Traps

• Inertial samplers

• Particles impacted on

coated glass slide or

adhesive tape

• Advantages: non-

selective, direct analysis

after collection

• Disadvantages: does not

assess viability,

speciation difficult,

Aspergillus and

Penicillium cannot be

distinguished


• Similar principle as spore trap

• But collect on agar plates

• Single stage or multi-stage

Impactors

Anderson 6-stage Impactor


Other methods

• Fungal DNA (PCR), not readily available

– Very sensitive, may not be specific to growth

• Microbial VOCs

– Not sensitive due to low levels, not specific due to other indoor sources.

• Glucans

– May estimate total fungal biomass, but cannot be used to identify

specific fungi


Interpreting reports from mold investigations

• Qualifications of the investigator

– No recognized credential; generally Certified Industrial Hygienists (CIH)

– Training? Experience? Practices? What is their rationale for sampling?

– Knows limits regarding relationship between mold and illness?

– Assess possible COI: independent of potential remediator?

• Physical inspection and narrative report: scope of work,

building history, moisture analysis, photos

• Sampling when appropriate to test hypotheses or needed

documentation

– Are the types and amounts of airborne mold spores greater than usual?

– Are airborne mold spores arising from a source of mold growth?

• Sampling strategy

– Indoors compared to outdoors; part of building compared to other parts

– Representative sampling of surfaces if needed


Interpretation of mold sampling results

• Qualified laboratory?

– American Industrial Hygiene Association accreditation

– AAAAI certifies proficient individuals to read

• Typical “grab samples” of air (1 to 10 min.) are a “snapshot” of

highly variable airborne spore levels

• Differences in genera/species indoors vs. outdoors may be

more important than relative spore concentrations

– Indicator species: Chaetomium and Stachybotrys rarely occur in

buildings without water damage

• Tape samples of surfaces may show mycelia and

reproductive structures verifying growth


Cases


Questions?


Additional Sources

• American Society of Heating Refrigeration and Air

Conditioning Engineers (ASHRAE). Indoor Air Quality Guide.

• USEPA. Indoor Air Quality, An Introduction for Health

Professionals. https://www.epa.gov/indoor-air-quality-iaq/indoor-air-

pollution-introduction-health-professionals-printable-version

• Other EPA IAQ publications and tools https://www.epa.gov/indoor-

air-quality-iaq

https://www.epa.gov/indoor-air-quality-iaq/indoor-air-pollution-introduction-health-professionals-printable-version

https://www.epa.gov/indoor-air-quality-iaq

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