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EHST 3900 1

EHST 3900:

Introduction to

Occupational Health

 To describe impacts of indoor air quality

(IAQ) on health

 To describe the building environment

 To describe building heating, ventilating,

and air-conditioning (HVAC) systems

 To describe how HVAC systems impact air

quality

 To list pollutant categories

 Health Effects Related to IAQ

 Buildings and Building Environments

 Ventilation

 Pollutant Categories

 Preventative Measures and Maintaining

Good IAQ

Safe haven from

inclement weather,

temperature extremes,

and outdoor air

pollutants

 Modern buildings provide wholly

artificial environments

 Sealed windows

 Tight building construction

 Forced air heating and cooling

systems

 Synthetic interior finishes

 Windowless interiors

 Partitioned offices

 Effects on comfort, health and

productivity are being recognized

 Infectious disease known to be more readily

transmitted indoors

 Consequences of long-term exposure to low

levels of indoor pollutants

 Building-related issues have led to increased

awareness of indoor air quality (IAQ)

 Poor ventilation

 Asbestos

 Radon

 Lead

 Formaldehyde

 Legionnaires’ disease

 Mold

EHST 3900 2

 Help render the indoor environment at least

as safe as the outdoors

 Keep parameters within the comfort range

for most individuals

 Acceptable IAQ

 “Air in which there are no known contaminants

at harmful concentrations as determined by

cognizant authorities and with which a

substantial majority (80% or more) of the people

exposed do not express dissatisfaction”

 American Society of Heating, Refrigerating,

and Air-Conditioning Engineers (ASHRAE)

 Some of the most challenging problems in the

nonindustrial occupational environment

 Requires knowledge of

 Buildings and their maintenance

 Construction

 Ventilation systems

 Sources of chemical and biological

contaminants and their health effects

 Building occupants’ concerns and their

sensitivities

 Current IAQ guidelines, standards, and

practices

1. Occupants (contagious diseases, carriage of

allergens and other agents on clothing,

tobacco smoke)

2. Building components (VOCs, particles, fibers)

3. Contamination of building components

(microbial agents, other allergens, pesticides)

4. Outdoor air and other sources (chemical air

pollutants, microorganisms, other allergens,

radon)

 Tight building syndrome

 Building-related illness

 Building-related disease

 Sick building syndrome

EHST 3900 3

 Diseases with objective clinical findings

that have been clearly related to building

occupancy include

 Hypersensitivity diseases

 Infectious diseases

 Toxic syndromes

 Examples

 Hypersensitivity pneumonitis (also

called allergic alveolitis)

 Humidifier fever

 Allergic asthma

 Allergic rhinitis

Dust mites and other allergens,

microorganisms, and some chemicals

 triggers asthma attacks.

Exposure of young children to ETS and

dust mites  development of asthma

 Contagious illnesses readily spread

through indoor air, especially in crowded

environments

 Legionnaires’ disease

 The only infectious disease that is

commonly spread from environmental

reservoirs

 Tuberculosis

 Influenza

 Measles

 Result from exposure to specific chemical

agents (e.g., carbon monoxide,

pesticides, or microbial toxins)

 Long-term (years) exposure to indoor air

pollutants (i.e. radon and ETS) may result

in increased risk of lung cancer.

 Most toxic agents caused by exposures to

chemicals derived from

 Combustion (CO or NO2)

 Activities or materials used in the

environment (VOCs)

EHST 3900 4

 Building occupants experience acute

health and comfort effects that appear to

be linked to time spent in a building, but

no specific illness or cause can be

identified.

http://www.epa.gov/iaq/pdfs/sick_building_factsheet.pdf

 A complex of occupant symptoms

 Nasal irritation

 Sinus congestion

 Eye irritation

 Nonproductive cough

 Headaches

 Fatigue or lethargy

 Dry skin

 Dizziness

 Nausea

 Symptoms are subjective, rarely

associated with objective clinical findings

 Typically present in some occupants of all

buildings at some time

 Outbreak of SBS

 Incidence rate at least 20%

 Some commonality among the symptoms

 Clear temporal association between

symptoms and building occupancy

 Outbreaks of SBS attributed to exposure

to

 Volatile organic compounds (VOCs)

 Low relative humidity

 Endotoxin

 House dust

 Unknown exposures due to inadequate

supplies of outdoor air

Environmentally

caused symptoms

Symptoms created

by suggestion

Symptoms

resulting from on-

the-job or other

stresses

 Schools

 Apartment buildings

 Offices

 Hospitals

 Medical centers

 Hotels

 Retail establishments

 Government buildings

 Nursing homes

 Administrative offices

of manufacturing

facilities

EHST 3900 5

New

Construction

Maintenance Renovation

Demolition

Primary objective:

• To prevent health effects

• To ensure comfortable conditions for

people in the building (children, immuno-

compromised patients, or the public)

 Thermal Comfort

 Relative Humidity

 Odors and IAQ

 Greatest source of dissatisfaction with IAQ

 Subject to individual preference

 Small swings in temperature (1–2 °F) can

affect thermal comfort

“Condition of mind

which expresses

satisfaction with the

thermal environment.”

– ASHRAE

 Personal control over temperature settings in

work areas often is a means of increasing

satisfaction

 Personal activity

 Clothing

 Fitness level

 Air temperature

 Air movement

 Relative humidity (RH)

 Elevated temperatures and RH

 Perception of poor IAQ  more

complaints

 Formaldehyde and other VOCs 

emitted at greater rates from building

materials and furnishings

EHST 3900 6

 Extremes in RH  poor IAQ

 Low RH blamed for

 Some of the symptoms of SBS

 Increased susceptibility to infectious

disease

 Exacerbation of asthma

 Eye irritation

 Throat irritation

 Cough

 Extremes in RH  poor IAQ

 High RH (>60%)

 Growth of microorganisms on surfaces

 Survival of the house dust mite, a source

for potent asthma-inducing

 Adverse respiratory health effects

(asthma)

 The facet of poor air quality that is most

apparent is odor.

 Establishment of ventilation rate standards

 control of unpleasant odor (human body

odor, smell of fresh wood and paint, tobacco

smoke)

SBS

Mechanically ventilated, air-

conditioned buildings

Inadequate amount or distribution

of outdoor (fresh) air

Effluents from human

occupants and their

activities

Effluents from building

materials and other

sources

 Heating, ventilating, and air-conditioning

(HVAC) systems

 Control IAQ by

 Providing outdoor air

 Filtering, mixing, and distributing both

outdoor and indoor air to the occupied space

 Providing some level of temperature and

humidity control

CAUTION!

HVAC systems may act as sources for specific

pollutants including VOCs, fibers and other

particles, and biological pollutants.

 Outdoor air

intakes

 Intake fans

 Filter banks

 Heat exchange

 Distribution fans

and ductwork

 Diffusers (to

provide mixing in

the occupied

space)

 System for returning air to the central system

EHST 3900 7

 Purpose: Delivery of air quality that is

acceptable to a majority of building

occupants

 Means: Correct installation, operation and

maintenance of HVAC systems

 The system must be

 Designed appropriately

 Built as designed

 Operated according to design

specifications

 Maintained in top condition

 Not modified

 To provide adequate ventilation

theoretically over the life of the building

 Pressure imbalances within the building may bring contaminated air into occupied spaces.

 Unplanned airflows through buildings can be the source of moisture, mold, or unexplained contamination of indoor air.

 Quality of the outside air may deteriorate.

 Budget cutting measures may reduce the degree of maintenance and operation of the system.

 Renovation of tenant spaces may have unforeseen consequences on the delivery of ventilation air to building occupants.

 ASHRAE standards

 ASTM standards

 EPA National Ambient Air Quality Standards

 Health Canada’s Exposure Guidelines for

Residential Indoor Air Quality

 World Health Organization (WHO) Guidelines

for Air Quality

Fungal Growth in Indoor Environment

 ACGIH’s Bioaerosols: Assessment and

Control

 EPA’s Mold Remediation in Schools and

Commercial Buildings

 New York City Department of Health’s

Guidelines on Assessment and Remediation

of Fungi in Indoor Environments

 IICRC Standard and Reference Guide for

Professional Water Damage Restoration

 Chemical Agents

 Carbon dioxide

 Carbon monoxide

 Nitrogen and sulfur oxides

 Environmental tobacco

smoke

 Particulate matter

 Fibers

 Ozone

 Formaldehyde

 Other VOCs

 Radon

 Biological Agents

 Allergens

 Biological toxins

 Microbial VOCs

EHST 3900 8

 Sources of indoor air contaminants of a

chemical nature may vary

 Fuel combustion

 Smoking

 Building materials and furnishings

 Cleaning agents, paints and adhesives

 Natural sources (radon)

 Include typical outdoor air pollutants and

chemicals generated indoors in buildings

 Not typically considered an indoor air

contaminant but is measured

 To assess the building ventilation in IAQ

investigations

 As a means of controlling ventilation to

auditoriums or other spaces with variable

occupancy

 Source: Exhaled air; unvented or poorly vented

combustion appliances; ETS

 Typical indoor levels (ranging from 500 to

several thousand ppm)

 Not as a cause of health effects

 As a surrogate for other indoor pollutants, or

an indicator of inadequate ventilation air

 >800 ppm

 Increased air quality complaints

 An indication of a lack of fresh air or

inadequate mixing of air in an occupied area

 An odorless, tasteless, colorless gas

 Produced by incomplete combustion of

petroleum products in internal

combustion engines

 A chemical asphyxiant

 Interferes with the functioning of hemoglobin

by competing with oxygen for binding to the

heme groups

 Hemoglobin

 Has a much higher affinity for CO than O2

 Environmental tobacco smoke (ETS)

 Has been one of the most frequent causes

of complaints for building occupants

 Releases a complex mixture of chemicals

and particles into the air (changes as it

ages)

 Side-stream smoke

 Diluted by room air but contains the

same kinds of toxic and carcinogenic

substances as inhaled smoke

EHST 3900 9

 Carbon monoxide (CO)

 Particles

 Nitrogen oxides

 Carbon dioxide (CO2)

 Hydrogen cyanide

 Formaldehyde

 Other gases

 Other VOCs

 Naturally occurring, odorless, and

colorless gas produced by the breakdown

of uranium in soil, rock, and water

 Exposure: Entry into buildings through

openings or cracks in the foundation

Uranium Radon

Radon

daughters

 Inhalation of radon daughters has been

linked to lung cancer

 ~5000 to 20,000 deaths per year caused

by exposure to radon

 Second-leading cause of lung cancer in

the U.S.

 One of the best ways to prevent IAQ problems is to design buildings with IAQ in mind from the beginning.

 OH professionals working closely with architects and construction professionals

 Good ventilation system design

 Proper layout of the interior space

 Proper exterior layout (locating supply air intakes for HVAC)

 Proper location of cooling towers

 Use of low-emission building materials

EHST 3900 10

 Using building materials and furnishings

that do not emit excessive VOCs

 Choosing low-odor, nontoxic adhesives,

sealants, and paints

 Scheduling building renovations and

repairs (i.e. roofing, painting and

carpeting) during nonworking hours

 Proper maintenance of buildings

 Maintaining and inspecting HVAC systems on a

regular basis

 Utilizing routine and thorough cleaning and

housekeeping services

 Addressing moisture problems and water

leaks as soon as possible

 IAQ is an important concern in non-

industrial working environments.

 Contaminants affecting IAQ comes from

various sources in a building.

 Health effects related to IAQ problems

may have subjective or objective-based

symptoms.

 Prevention of IAQ problems starts best

during the building design stage.