Indoor Air Quality

Occupational Safety& Health Section

Labour Department

Factors Affecting IAQ

Environmental Air QualityWork activitiesBuilding designVentilation system - mechanical vs. naturalAnimals including insectsTemperatureHumidityPeople

Factors Affecting IAQ

Housekeeping standards in the work areaPersonal habits e.g. perfumes, insecticidesStorage Housekeeping in area of the air

conditioning systemTemperature controlChanges to the building design not

compatible with the ventilation system

Factors Affecting IAQ

Carpeting and soft furnishingsUse of split system unitsPest control application/Painting etc without venting the area afterDuct conditions (mold growth/animal danger)OdoursOffice plants

Ventilation [S 52]

Effective and suitable provision shall be made for Circulation of fresh air Removal of all substance, fumes, dust

and other impurities that are likely to be injurious to health

Temperature [ S 51 ]Required to:

Use methods to ensure reasonable temperature

Chief Labour Officer may order the following: Raising the height of the roof of a building or

room Insulating of the roof (use of insulating

materials; construction of a double roof) Increase in the number of air changes per hour

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Acceptable Indoor Air Quality

Acceptable indoor air quality is air in which there are no known contaminants at harmful levels; and

With which the majority of persons (at least 80%) do not express dissatisfaction based on several criteria such as relative humidity, odours and air movement.

(ASHRAE Standard 62-2001 – Ventilation for Acceptable Indoor Air Quality)

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Forms of Heating, Ventilation and Air Conditioning (HVAC) Systems

Natural ventilation

Mechanical ventilation

Combination of Natural and Mechanical Ventilation

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Natural VentilationAn example of natural ventilation is the use

of open windows to utilise the ‘fresh’ air and the natural breeze.

Advantage: There are numerous air exchanges.

Disadvantage: Limited control of the temperature.

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Mechanical Ventilation

An example of mechanical ventilation is the use of fans.

Advantage: Utilises natural fresh air with some control over air movement.

Disadvantage: Minimal control of the temperature.

90 degrees F

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Mechanical Ventilation (2)

Another example of mechanical ventilation is the use air conditioning systems.

Advantage: Greater control of the room temperature to provide a

cooler atmosphere.

Disadvantage: Some degree of circulation of the same air.

Window AC Unit

Ductless Single Zone Mini-Split Wall-Mounted Cool Only Air Conditioner

Central System

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HVAC ConsiderationsChoosing the correct system for the area and

activities undertaken The type of system (central system, split system,

window unit) Filter type) Materials used (galvanised vs. fiberboard ducting)

Are there provisions for the intake of make up air or the exhaust of contaminated or stale air?

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Where are the intake and exhaust located?How often is the system serviced and what

is involved in the service?How often is the area serviced by the

system cleaned?What are the housekeeping practices,

particularly in the plant rooms?

HVAC Considerations (2)

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The compartmentalisation of the building -

How is the building divided ? Is one room at a different potential to

another? Are there closed doorways or ceiling

partitions which restrict the flow of air? Are there intake and exhaust vents in each

room?

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The presence of indoor sources of contaminants and their magnitude -

What goes on in the rooms being serviced by the system?

Are there pollution sources near intake areas?

Are there items which would cause the accumulation of dust?

Are there conditions which would create biological contaminants?

Health Effects of IAQ

Two main categoriesBuilding Related IllnessSick Building Syndrome

Building Related Illness

Illnesses where the specific diagnosis can be made, including the identification of the causative agent

e.g. Breakdown of building materials (Sinusitis)

Sick Building Syndrome

Sick building syndrome is defined as a persistent set of symptoms occurring in greater than 20 percent of a building’s occupants, with no readily recognisable cause.

Sick Building Syndrome

Signs and symptoms include

headache

nausea

dizziness

coughing

muscle pain

fatigue

dermatitis

eye, nose, throat, and respiratory irritation

difficulty concentrating

sensitivity to odors

Some Common Substances

Carbon dioxide - from human respiration and processes involving combustion.

Carbon monoxide - sources include tobacco smoke and vehicular exhaust.

Formaldehyde - from the off-gassing from plywood; particle board; carpeting and fabric; glues and adhesives.

Nitrogen oxides - vehicular exhaust; tobacco smoke

Ozone - copy machinesVolatile Organic Compounds (VOC) -

paints; cleaning compounds; moth-balls; Ammonia Cleaning agents

More Common Substances

‘Mould Invasion!! – Fungi in my air

The cold hard fact is - MOULD IS EVERYWHERE ALL THE TIME! Indoors, outdoors and in the home.

Mould should not be ‘growing’ indoors.If indoor levels are higher than outdoor

levels it is possible that indoor conditions might be promoting growth.

Mould requires moisture and nutrients to grow.

Relative humidity and moisture sources (e.g. leaks) must therefore be strictly controlled to prevent mould growth.

Mould produces toxins which can cause allergic reactions in some ‘susceptible’ persons e.g. persons with compromised immune systems; respiratory conditions (asthma; sinusitis) .

Many persons do not experience any adverse effects from the presence of mould.

Mould can be cleaned by using mild detergent and water or commercially available fungicide products.

Care should be taken to wear respiratory protection in addition to gloves and eye protection. The Material Safety Data Sheet must also be followed.

Cleaning can only be done if the material is non-porous. It is also essential that the item be allowed to dry thoroughly.

Evaluating IAQ

The basic parameters considered when evaluating IAQ are

• Relative humidity

• Temperature

• Carbon dioxide

Depending on the circumstances other parameters could be considered.

Recommended levels: Relative humidity: 30 – 60% (should be

maintained below 70%)

Temperature: 23 – 26 oC (air conditioned)

Carbon dioxide: 1000 ppm (less than 700 ppm above outdoor levels; complaints

may occur above 800 ppm)

Outdoor air requirement vary with facility but for offices 20 cfm/person is recommended (ACGIH)

Other Related Issues

Psycho-social relationships (labour relations)

Psychological component (stress, psychosomatic)

AElcock

Occupational Safety & Health SectionLabour Department

Promoting the attainment and maintenance of desirable standards of occupational safety and

health practice in Barbados.