Air - Indoor Air Quality

Indoor

Air

Quality

Guide Workplace Health and Safety gde21Indoor Air Quality Page 2 of 11 November 1995

WORKPLACE HEALTH and SAFETYDEPARTMENT OF TRAINING AND INDUSTRIAL RELATIONS

This guide has been produced by the Workplace Health and Safety Council to provide employers withinformation on the considerations needed when assessing the need to introduce control measures toprovide a healthy and comfortable working environment for their employees.The guide aims to help improve the quality of work environments by outlining factors affecting indoorair quality and suggesting ways of managing the quality of indoor air for all workplaces.

ISBN 0 7242 6581 3


Contents

LEGISLATION AND STANDARDS 4

INDOOR AIR QUALITY 4

WHAT AFFECTS INDOOR AIR QUALITY 4

Temperature 5

Humidity 5

Air Movement 6

Air Changes 6

Air Contaminants - From Inside the Workplace 6

Air Contaminants - From Outside the Workplace 7

WAYS OF MANAGING INDOOR AIR QUALITY 8

Indoor Air Management Program 8

Investigation 8

Source Removal or Substitution 9

Workplace or Work Process Modification 9

Ventilation 9

Air Cleaning 10

Administrative measures 10

ADDITIONAL REFERENCES 11


LEGISLATION AND STANDARDS

The Workplace Health and Safety Act 1995places an obligation on an employer to ensurethat exposure to extreme thermal environmentsand health risks from air contaminants in theworkplace are controlled. A range of standardsand guidelines are available to assist personsin managing indoor air quality. To meet theobligations specified in the Act, persons mustensure that the provisions of the relevantcompliance standards are followed. Obligationsof persons for indoor air quality are shared by: building professionals such as designers

and architects building owners and managers building material manufacturers building services engineers tenants and other occupants.

Standards and guidelines from various sourceshave to be used to address individualworkplace situations. A number of thestandards and other references relating toindoor air quality are provided at the end of thisdocument.

INDOOR AIR QUALITY

Indoor air quality is a significantoccupational health issue reflecting: an increasing number of people spendingtheir working lives indoors the construction of sealed buildings with windows which cannot be opened the increased use of synthetic materials andnew technology energy conservation measures that reducethe amount of outdoor air being circulated.

DefinitionThe National Health and Medical ResearchCouncil defines indoor air as the air within abuilding occupied for a period of at least onehour by people of varying states of health.

People are entitled to work in an environmentwhich is as comfortable and healthy aspossible. In the workplace, people may beexposed to infection risks which can betransmitted through contact with other people.Overcrowded workplaces and poorlymaintained air-conditioning systems mayincrease these risks. Risks may also beincreased by: tobacco smoking

by-products of building materials,furnishings, and modern office equipment

cleaning products polluted outdoor air.

BackgroundA number of Australian and overseas studieshave identified the high cost of poor qualityindoor air. These costs have included directmedical costs, lost productivity and damage tomaterial and equipment. Lost productivity in theUSA is estimated to be nearly five times that ofdirect medical costs.An increasing number of studies have focusedon discomfort or illnesses arising from indoorenvironments. Such problems are generallydivided into the following categories: Sick Building Syndrome (SBS) Building Related Illnesses (BRI).

According to the World Health Organisation,SBS refers to a range of non-specificsymptoms which can affect a significantnumber of building occupants. Itchy eyes,tiredness or headaches are typical of suchcomplaints. Such symptoms have no clearcauses and abate when a person is no longerinside the building.Building Related Illnesses are those which havespecific or diagnosable causes. Allergicreactions and infections such as legionnaires'disease are examples. BRI symptoms typicallypersist for some time after a person has left thebuilding.

WHAT AFFECTS INDOOR AIRQUALITY

Air quality is influenced by: temperature humidity air movement air contaminants.

An air-conditioned workplace should provide athermally comfortable temperature range. Anair-conditioning system should: supply fresh air, exhaust stale air and

filter recycled and outdoor air provide a generally acceptable environment

in terms of air temperature, humidity and airmovement

prevent excessive accumulation ofunpleasant odours


prevent excessive accumulation of expiredcarbon dioxide to an acceptable level

reduce excessive accumulation of indoor aircontaminants from work activities, buildingmaterials, and external sources toacceptable levels.

If an air-conditioning system is installed, itshould operate whenever people are in theworkplace. Systems which operate byautomatic timer should have an override facilityif people are required to use the building out ofhours. If air-conditioning systems are switchedoff when the workplace is empty, they shouldbe switched back on before people return towork.In some instances it may be unsuitable to air-condition all parts of the workplace. Examplesinclude: Steel fabrication works where large volumes

of air are required to air-condition the workarea

Foundries and bakeries where heat sourcesare created in the workplace (spot coolingmay be more appropriate)

Battery manufacture and electroplatingworks - environment created by the workcarried out.

The quality of indoor air at a workplace withoutair-conditioning largely depends on: outdoor climate air contaminants generated from indoors

and outdoors work processes being performed quality of natural ventilation including

building design, location and layout, andnumber of windows that can be opened.

Temperature

In an air-conditioned workplace, the idealtemperature range is between 19 - 23C inwinter and 22 - 24C in summer.Temperature in an air-conditioned workplaceshould be adjusted to match work activities,normal work clothing and the outdoor climate.In extremely hot conditions, some air-conditioning systems may not maintain idealindoor temperatures. Where the outside shadetemperature exceeds 32C, the insidetemperature should be at least 8C below thattemperature.

Direct temperature control is difficult inworkplaces without air-conditioning. Workers inhot climates should not be subjected toexcessive heat stress conditions. If heat stressis likely, expert advice should be obtained.The following factors need to be considered inassessing the thermal environment:

the effect of solar heat load, for example,the sun shining on a workplace

any uneven distribution of solar heat load the heat sources inside the workplace, for

example, computing and electricalequipment, ovens and hotplates

the nature of work being performed, forexample, people working on an assemblyline may require slightly lower temperaturesthan employees working in an officeenvironment

clothing worn by workers, for example,foundry workers are required to wearprotective clothing

different perceptions of thermal conditionsand comfort.

Ways to control temperature At an air-conditioned workplace, the air-conditioningshould be adjustable in order to meet thetemperature requirements of differentworkplace areas. Other means of temperaturecontrol include providing reflective glass,screens, blinds, and awnings over windows,and relocating work stations from heat sources.

In workplaces without air-conditioning, expertadvice should be sought for heat stress riskmanagement.

Humidity

Relative humidity (RH) levels should ideally bebetween 40% and 60%. The higher the relativehumidity, the less able the body is to evaporatemoisture (sweat) from the skin. Extremes inrelative humidity (< 20% and > 80%) should beavoided where possible.

Extremely low relative humidity levels causeeyes, noses and throats to dry, This producesirritations and soreness and increasessusceptibility to infection. Low humidity alsoincreases the problem of static electricity.

In high relative humidity conditions, themoisture in the air promotes the growth of fungiand mould.

WAYS TO CONTROL THE EFFECTS OFHIGH RELATIVE HUMIDITY

High relative humidity generally occurs inworkplaces without air-conditioning, forexample, laundries. If work areas constantlyexperience high humidity, employers shouldroster workers for short periods only. If highhumidity persists, employers should considerinstalling dehumidification devices. Highhumidity in an air-conditioned workplacesuggests a design/maintenance problem.


Air Movement

Too little air flow may create stuffy anduncomfortable conditions. Too much airmovement may result in draughts andexcessive cold.

RECOMMENDED RANGE OF AIRMOVEMENT1*

Occupied Office and Factory Interiors(measured in metres per second)

Officemin max

Factorymin max

21C 40-60%RH24C 40-60%RH

0.I 0.20.15 0.4

0.I ...0.30.25 ..0.5

Factors influencing air movement include:Internal Partitioning. Rooms created by fullheight partitions in areas originally designed as"open plan" can become dead spaces where airhas no exit path when doors are closed.Air flow into the room is diminished, making theroom stuffy and uncomfortable. Incorporatingventilation grills in doors may help by allowingair to flow in and out of work areas. Thisinvolves consultation with air-conditioningmaintenance personnel/contractors.

Balanced Air-conditioning Systems. The air-conditioning system is balanced if there isoptimum air flow in all the areas supplied. Toachieve such conditions it is usually necessaryto adjust flow in individual ducts after allinternal building is completed. Systems shouldalso be adjusted whenever substantial changesin the activities, layout and occupancy of theworkplace occurs.

Filter Maintenance. Regular maintenance offilters will ensure optimum air flow through theair-conditioning system and filter efficiency incapturing particulate contaminants.

Air Changes

The term 'Air Changes per Hour' or 'ACH' hastraditionally been used to describe the overallamount of air entering and leaving a building. Itis a measure of the rate of exchange of air in abuilding with outside air. The term takes the

1 Occupational Safety & Health in CommonwealthGovernmentEmployment Code of Practice - 202 Ventilation andThermal Control

mechanical and natural ventilation of a buildinginto account.

ACH is not usually used in modern offices andbuildings which are air-conditioned and wellsealed. Instead, the rate of outdoor air supply isusually used as a measure of the adequacy ofventilation. Australian Standard (A.S.) 1668.2provides guidance on the outdoor airrequirements for different classes ofoccupancy. For most office situations, anoutdoor air rate of 10 -15 litres per second perperson is required.

Air Contaminants - From Inside theWorkplace

Common sources of indoor air contaminantsand how to deal with them include:

Carbon Dioxide (CO2) is a major respiratoryand combustion product. It is not commonlyconsidered as a 'pollutant', but may affect thegeneral comfort of occupants. Carbon dioxidelevels are usually a good indicator of theeffectiveness of the ventilation system inreplacing stale air with outdoor fresh air. Indoorlevels of carbon dioxide should be maintainedat below 1,000 parts per million (ppm). Carbondioxide levels exceeding limit indicate that theamount of fresh air delivered by an airdelivered by an air-conditioning system maynot be adequate.

Combustion By-products include carbonmonoxide (CO), oxides of nitrogen (NO andNO2) and a range of hydrocarbons. They arethe by-products of fuel used in unventedcombustion processes such as gas cooking andheating. Carbon monoxide interferes withoxygen transport in the blood stream and, inhigh concentrations, can cause death. Oxidesof nitrogen irritate the eyes and respiratorytract. Combustion equipment, such as gasappliances, generators and diesel or petrolcompressors should be installed andmaintained to ensure that workers are notexposed to emissions of combustion by-products.

Ozone. Any work process or equipment thatuses ultra-violet light or causes ionisation of theair may produce ozone. Such equipmentincludes laser printers, photocopiers andionisers. Ozone is highly toxic and has effectsat low concentrations. It may irritate the eyesand respiratory tract. As ozone is highlyreactive, it will generally be found only near thesource and will have little effect on the generalindoor environment.


Formaldehyde is usually given off frombuilding materials such as plywood, particleboard, some carpets and urea-formaldehydefoam insulation (UFFI). Formaldehyde is aneye and respiratory irritant and a suspectedhuman carcinogen. It is known to have causedasthmatic conditions in some people.Other Volatile Organic Compounds (VOC)have been identified in indoor environments.These are effluent from building materials,cosmetics, cleaning agents, waxes, carpets,furnishings, adhesives and paints. Exposure tothese compounds may cause a wide range ofhealth effects including headache, eye, throatand chest irritations.

Airborne Particles and their possible effectsinclude: combustion particles from

cooking/heating. Cooking smoke maycause respiratory tract infections

combustion particles from tobaccosmoking. Tobacco smoke may cause lungcancer

dusts from clothing, paper and carpets.Most dusts cause nasal and eye irritation.

fibres, such as asbestos, contained insome building materials. There isestablished evidence that asbestos cancause lung cancer and mesothelioma.

fibres such as fibreglass, commonlyused in the lining of air-conditioningductwork. Fibreglass can cause itching antiirritation to skin, eyes and upper respiratorysystems

Radon and Radon Products are radioactivedecay products of Radium - 226. They arefound in building materials made from certaintypes of rocks and soils. Radon is a colourlessgas which goes into the indoor air by diffusionfrom the ground, building materials andunderground water.

Higher concentrations are usually found inbasements and crawl spaces. Studiesconducted to date do not provide sufficientinformation to determine the level of radon inQueensland buildings.

Radon could cause damage to the lungsthrough inhalation and indoor radon levels havebeen associated with an increased risk of lungcancer.

Environmental Tobacco Smoke (ETS) is thecollective name for a group of chemicalsintroduced into the indoor environment fromcigarette smoke. ETS includes both sidestreamsmoke generated by a burning cigarette andmainstream smoke exhaled by the smoker.

Exposure to ETS in indoor environments hasbeen associated with a range of respiratoryconditions including exacerbation of asthmaand lung cancer. An employer should provide aworkplace free from tobacco smoke.Microbiological Pollutants include viruses,bacteria and fungi. They can cause infectionsand allergic reactions in indoor airenvironments. Bacteria and viruses are mostcommonly spread from person to person.Ventilation systems are unlikely to play asignificant role in the spread of viral illnesses,as they are not a source of viruses and do notprovide conditions for viral replication.

Certain bacterial infections such aslegionnaires' disease, can be spread throughair-conditioning systems which use coolingtowers.

Fungal growths most commonly occur whenthere is: abnormally high humidity poorly maintained air-conditioning systems water damage to carpeting caused by

flooding and leaks.

Control measures are set out in AustralianStandard (A.S.) 3666 Air - handling and watersystems of buildings - Microbial control.

Dust Mites may cause respiratory systemallergies and are more prevalent in warmhumid conditions. High dust mite populationsare more likely to occur in buildings which havehad their air-conditioning switched off forextended periods (weeks - months). If dustmites are identified as a problem, specialtreatments may be required. Regular andthorough cleaning to remove dust in which dustmites breed is essential.

Unpleasant Odours are usually harmless butmay be offensive. Quantifying the smell andidentifying the source can be difficult. Ifchemical deodorisers are used to maskunpleasant odours they should be used withcaution as they could create another indoor airproblem.

Air Contaminants - From Outside theWorkplaceIn most cases, outdoor contaminants onlycontribute a small fraction of the overall indoorair pollution problem, However, thesecontaminants should still be minimised.Outdoor air contaminantscan enter a buildingthrough air-conditioning systems and openedwindows.


Neighbouring activities may also affect thelevel of contaminants.

Some of the more common external sources ofcontaminants are: particulate originating from combustion in

coal-fired boilers, motor vehicles or dustfrom construction sites.

gaseous combustion products whichinclude nitrogen dioxide and nitric oxide,sulphur dioxide and carbon monoxide.These are generated as by-products fromthe burning of fuels in industrial processesand from road traffic.

volatile organic compounds (VOC) suchas solvents vaporised from industrialsources, for example, chlorinatedhydrocarbons from degreasing tanks; somealso originate from incomplete combustionof fuels.

microbiological agents which includespores of fungi and pollens and are the

major microbiological agents in the externalenvironment.

Ways of Managing Indoor Air QualityIndoor air quality in the workplace should bemanaged by implementing a managementprogram (see flowchart). Concerns should beaddressed before significant health problemsdevelop, and staff morale, productivity andorganisational image deteriorate. If an indoorair quality concern is identified in the course ofthe program, investigation should startimmediately. If no problem is apparent, theassessment should still be performed on aregular basis. Significant changes to theworkplace such as refurbishment also warrantconducting another assessment

Indoor Air Management Program

InvestigationIf there is a problem with the quality of indoorair, initial steps should focus on identifying thesource of the problem. Problems may beassociated with: temperature humidity air flow inadequate fresh air

air contaminants

People occupying a building may exhibit arange of physical symptoms as a result of poorquality indoor air including: eye and skin irritationsrespiratory tract irritation and infections headaches fatigue miscellaneous complaints


Once a contaminant has been identified, thenext step should be to attempt to reduce it to apractical minimum. This may be achieved by: removing or substituting the cause

modifying the workplace or work processes

improving ventilation air cleaning administrative measures

COMMON CAUSES OF INDOOR AIR PROBLEMS

air-conditioning design operation maintenance

examples inadequate cooling capacity not turned on before occupants arrive filters not changed

building material new damaged

paint, fabric, furnishing releasing pollutants mould on waterdamaged carpet

work activities photocopying maintenance neighbouring activities use of chemicals heat producing

release ozone dust/fibres released cooking solvent based glue ovens, driers

people smoking body odour perfumes

outdoor air ambient pollutants exhaust fumes construction

pollens, sulphur dioxide car parks dust

Source Removal or SubstitutionThis is the most effective method of reducingindoor air pollution, for example, replacingsolvent-based paints with water-based paints.These paints will generally produce less toxicvapour.

Workplace or Work ProcessModificationThis reduces the workers' exposure tocontaminants. One example would be to movea photocopying machine away fromworkstations.

Plans for introducing new building materials orwork processes should include early liaison withmaintenance personnel/contractors regarding

any precautions necessary to minimise thepotential of indoor air quality problems.

Ventilation

Ventilation is one of the means by which indoorair is treated to achieve acceptable indoor airquality. One measure may be to relocate thefresh air intake away from the neighbouringindustrial activities or heavy traffic. Othermechanical ventilation measures include theuse of:' improved dilution ventilation. Low level

contaminations such as paper dust and bodyodour can be controlled by introducingsufficient fresh outdoor air, or byrecirculating appropriately filtered air intothe workplace. Areas of higher levelcontaminations from sources such as highusage photocopying machines may require


isolation or separately ventilated areas. Itmay be necessary to run air-conditioningcontinuously where new building productswhich are known to emit some air pollutantshave been used.

local exhaust ventilation designed toremove air contaminants close to theirsource is useful in controlling localindividual contaminant sources such ascooking stoves and soldering processes.Consideration should be given to localexhaust ventilation where devices orprocesses likely to emit fumes, heat orodours are used.

Ventilation systems should be designed andmaintained to comply with AS 1668.2 and AS3666.

Air Cleaning

Air cleaning usually works better withparticulate matter such as combustion particlesand fibrous dusts. Indoor air can be cleaned byair filters and electrostatic precipitators fitted inthe ventilation system or as stand-alonemodels. For best effect, cleaning devices mustbe regularly maintained and serviced. If poorlymonitored, these devices could give a falsesense of security and even hinder theperformance of the ventilation system. Toachieve the best results, expert advice shouldbe sought in selecting and installing thesedevices.

Administrative measures

Administrative measures include: developing communication channels

between workers and employers to facilitateidentification of indoor air problems.

cleaning the workplace, for example, thebuilding fabrics or ventilation systems toeliminate sources of contaminants from splitmaterials, deposited dust and absorbedmaterials on surfaces.

regular service and maintenance to ensurethat ventilation systems are functioningsatisfactorily.

designating the workplace a non-smokingarea. If there is a designated smoking area,the air-conditioning system should becompletely separated from that of the non-smoking area as ETS cannot be totallyfiltered out by the air-conditioning system.

Indoor painting, carpet laying, and sprayingof pesticides should be performed outsidenormal working hours. The area should beventilated before people are expected toreturn to the workplace.

allowing a greater amount of outdoor air toenter the workplace in order to dilute thecontaminant levels, for example, byadjusting the fresh air intake of the airconditioning system.

regular monitoring to ensure that controlmeasures are working effectively.

Unresolved problems may require services ofprofessionals such as industrial hygienists orindoor air specialists.


Additional References

Australian and New Zealand EnvironmentalCouncil Discussion Paper on Indoor AirPollution, (1990: ANZEC).

American Conference of GovernmentalIndustrial Hygienists. Guidelines for theAssessment of Bioaerosols in the IndoorEnvironment. (1989:ACGIH, Cincinnati, OH).

American Society of Heating, Refrigerating andAir-Conditioning Engineers. ASHRAE Standard62 - 1989 Ventilation for Acceptable Indoor AirQuality. (ASHRAE, Atlanta, GA).

Brooks B. & Davis W. Understanding Indoor AirQuality. (1992: CRC Press, Inc., Boca Raton,FI).

Building Owners and Managers Association ofAustralia. Managing Indoor Air Quality. (1994:BOMA Australia).

Department of Employment and IndustrialRelations. Code of Practice 202 - Ventilationand Thermal Control, (1983: AustralianGovernment Publishing Service, Canberra).

Environmental Protection Agency & USNationalInstitute for Occupational Safety and Health.Building Air Ouality - A Guide for BuildingOwners and Facility Managers. ( 199I: USGovernment Printing Office, Washington, DC).

Godish T. Indoor Air Pollution Control. (199I:Lewis Publishers, Chelsea, MI.)

National Health and Medical Research Council.Australian Guidelines for the Control ofLegionella and Legionnaire's Disease. (1988:Australian Government Publishing Service,Canberra).

National Health and Medical Research Council.The Health Effects of Passive Smoking. (UnderReview: Australian Government PrintingService, Canberra).

National Health and Medical Research Council.Interim National Indoor Air Quality Goalsrecommended by the National Health andMedical Research Council..(I993: NHMRC -Internal Document).

Samet J. & Spengler J., Eds. Indoor AirPollution - A Health Perspective. (199I: The]ohns Hopkins University Press, Baltimore,MD).

Standards Australia. AS 3666 - 1989 Air -Handling and Water Systems of Building -Microbial Control. (Standards Australia,Sydney).

Standards Australia. AS 1668.2 - 1991 The Useof Mechanical Ventilation and Air-Conditioningin Buildings Part 2: Mechanical Ventilation forAcceptable Indoor-Air Quality. (StandardsAustralia, Sydney).

Standards Australia. HB 32 - 1992 Control ofMicrobial Growth in Air Handling and WaterSystems in Buildings, (Standards Australia,Sydney).

Worksafe Australia. Exposure Standards forAtmospheric Contaminants in the OccupationalEnvironment. (199I: Standards Australia,Sydney).

Worksafe Australia (1994)~ Guidance Note onPassive Smoking in the Workplace, WorksafeAustralia, Sydney.

World Health Organisation. "Indoor Air QualityResearch", Report on a WHO Meeting. August2 I - 24, 1984. (EURO Reports and Studies103,Regional Office for Europe, Copenhagen).

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Air - Indoor Air Quality