study guide

1

 Air sampling strategies

 Air sampling process

 What agents to sample

 Preparation of report

 Who to sample?

 Maximum risk employees

 HEG

 Blanks

 Field

 Laboratory

 Sources of errors

 Sampling errors or bias

 Laboratory errors

 Sampling and analytical errors (SAEs)

 Limits of air sampling

 Vs actual absorbed dose

 Representativeness

 Conc unit conversion

 ppm  mg/m3

EHST 3700/3701:

Industrial Hygiene

 To enumerate the common complaints

associated with poor indoor air quality (IAQ)

 To describe basic HVAC systems and their

components

 To describe simple testing and

troubleshooting for IAQ problem evaluation

 To enumerate the contents of consensus

standards for IAQ

 To discuss contaminants affecting IAQ

 Indoor air quality as a public health concern

 Heating, ventilating and air conditioning

(HVAC) systems

 Basic instruments used in IAQ studies

 Microorganism contamination and IAQ

 Radon and asbestos

 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

2

 Indoor environmental quality

 Describes how inside air can affect a person's

health, comfort, and ability to work

 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)

 Temperature

 Humidity

 Stuffiness or lack of air circulation

 Odors

 Physical symptoms

 A complex of occupant symptoms that are

clearly related to building occupancy, but

that are not associated with objective

clinical signs

 Symptoms are subjective and nonspecific

 Nasal irritation

 Sinus congestion

 Eye irritation

 Nonproductive cough

 Headaches

 Fatigue or lethargy

 Dry skin

 Dizziness

 Nausea

 Diseases with objective clinical findings

that have been clearly related to building

occupancy include

 Hypersensitivity diseases

 Infectious diseases

 Toxic syndromes

3

 Pathogenic bacteria that cause Legionnaires'

disease

 Acquired its name after a July 1976 outbreak

of a disease that sickened 221 persons, causing

34 deaths

 First noticed among people attending a

convention of the American Legion in

Philadelphia

HVAC system

Chemical contamination

Microbial contamination

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)

IAQ problems

may be linked to

the occupants’

perception of

the air quality.

 Job satisfaction

 Personal and professional relationships

 Level of experience

 Social and economic issues

IAQ problems may be linked

to the degree of control

that occupants have over

their environment.

 No OSHA standards

 IAQ Guidelines

 CO2 levels < 800 ppm

 Relative humidity ≤ 60%

 Maintaining records for HVAC systems

 Exhausting designated smoking areas to the outside

and keeping them under negative pressure

 Locating air intakes of systems to prevent

capturing outside air contaminants

4

 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

 ASHRAE 62-1989: Ventilation for Acceptable

Air Quality

 ASHRAE 55-1992: Thermal Environmental

Conditions for Human Occupancy

 ASHRAE 52-1992: Methods of Testing Air

Cleaning Devices Used in General Ventilation

for Removing Particulate Matter

 Ventilation for Acceptable Air Quality

 Minimum features and performance

capabilities for HVAC systems in different

types of occupied buildings

 Offices

 Classrooms

 Laboratories

 Smoking lounges

 Existence of method for verifying that the

system is providing adequate volume of

airflow to the occupied space

 Delivery of air to areas where occupants are

located

 Design to prevent the growth of

microorganisms (i.e. self-draining pans,

steam humidifiers, unlined ducts)

 RH < 60%; CO2 < 1000 ppm

 Air intakes and outlets

located to avoid drawing

contaminants into the

system

 Filters, scrubbers and other

treatment methods used to

remove air contaminants

and maintain acceptable air

quality

 Accessibility of HVAC unit

for cleaning and

maintenance

 Thermal Environmental Conditions for Human

Occupancy

 Contains a description of the temperature

and humidity conditions accepted to most

occupants of a space

 Considers other factors

 Air movement

 Humidity

 Clothing

 Activity level

5

 Methods of Testing Air Cleaning Devices Used

in General Ventilation for Removing

Particulate Matter

 Contains 2 methods used to test the

effectiveness of air filters

 ASHRAE Arrestance Test

 For filters used to remove larger particles

 ASHRAE Dust Spot Efficiency Test

 For filters used to remove fine dust

Single zone,

constant

volume

Multiple zone,

constant

volume

Single zone,

variable

volume

Multiple zone,

variable

volume

IAQ problems related to

HVAC systems are often

attributable to poor or

irregular maintenance.

 Little or no outside air being drawn into the

system

 Poor system design, or installation of the

system not as designed

 Modifications to the system after installation

 Modification in the zones served by the unit

 Placement of air intakes near outside sources

of pollutants

6

 Buildup of noticeable odors

 Increased levels of carbon dioxide and other

undesirable gases

Carbon dioxide is

often used as an

indicator of HVAC

effectiveness in

supplying fresh

air to the

building.

 Unit capabilities exceeded by the zone’s

requirements for air volume and flow

 Outside air dampers are stuck or rusted

closed.

 Defective fans, motors or drive belts

 Blockage , sharp turns, and “user”

modifications of supply ducts

 Causes

 Blocked room diffuser

 Closed dampers

 Direct measurement of air velocity, V (fpm)

 Anemometer / velometer

 Measured at the face of the diffuser

 Calculation of volumetric airflow rate, Q

(cfm)

 Q = VA

 Anemometer reading: 10 fpm

 Diffuser dimension: 2 ft x 4 ft

 V = ?

 A = ?

 Q = VA = ?

4 ft

2 ft

7

 Addition or rearrangement of walls,

partitions, or major furnitures within the

space

 Adding, blocking off, or removing ducts

 Location: roofs, sides of

buildings, between

floors

 Checked visually for

blockage (i.e. leaves,

bird nests, debris on

screens), stuck or

malfunctioning louvers,

and other barriers to

airflow

 Should not be located

near sources of

pollutants

 Garbage dumpsters

 Parking structures

 Loading docks

 Incinerators

 Chemical storage

areas

 IAQ is one phenomenon increasing encountered

by OH professionals.

 Sources of IAQ problems may be related to HVAC

systems, chemical and microbial contamination.

 Sick building syndrome is a group of nonspecific,

subjective symptoms associated with poor IAQ.

 There is no OSHA standard for IAQ, but

consensus standards are used for design and

evaluation of HVAC systems.

 There are 4 main types of HVAC systems.

 Many IAQ complaints can be attributed to HVAC

maintenance and operation.