Indoor Air Quality (IAQ)

People spend more time indoors, thus have longer-time exposure to

pollutants in the indoor environments

Factors affecting Indoor Air Quality

• Outdoor air quality

• Indoor generation of pollutants• Pollution depletion mechanism (deposition and

chemical decay)

• Meteorological factors (affects air exchange) • Permeability of structure (affects air exchange)

• Ventilation measures (affects air exchange)

Indoor/outdoor relationship

• SO2: 0.3-0.7

• NO2: <1; > 1 (with stove in use)

• CO: ≥1

• HCs: >1

• HCHO: >1

• PM: <1 (no burning source)

Pollution sources at home

Sources Emissions

Tobacco smoking CO, VOC, RSP

Combustion systems for heating and cooking NO2, CO, SO2

Building materials, insulation materials and adhesive: asbestos, radon, formaldehyde

VOC

Surface finishes, paints VOC

Furniture formaldehyde

Cleaning materials, pesticides, sanitary and cosmetic facilities

VOC, halogenated solvents

Moist material and surface biological agents

Earth underlying at home radon

Woodstoves and fireplaces RSP, CP, PAH

Pollution sources at office

Sources Emissions

Copying machines O3, VOC

Air conditioning systems biological agents, CO and VOC.

Tobacco smoking CO, VOC, RSP

Building materials, insulation materials and adhesives

asbestos, radon, formaldehyde, VOC

Surface finishes paints, VOC

Office Equipment Emissions

Sources Emissions

Dry-process photocopying machines

Hydrocarbons, ozone, and particulate (toner powder)

Wet-process photocopying machine Aliphatic hydrocarbons, and ozone

Laser, Ink/bubble jet printers Hydrocarbons, RSP, and ozone

Fax machines Ozone and VOCs

Computer terminals Ozone, off-gassing VOCs

Sick Building Syndrome (SBS)

• A spectrum of non-specific symptoms with no identifiable cause:

- irritation of eyes, nose, throat, and sinuses

- headache, fatigue, lassitude

- dryness, rashes

- cough, short of breath

Procedures for investigating IAQ complaints

Do you have an explanationfor the complaint?

Finish

yes

no

Develop one or more hypotheses to explain the problem.Test by manipulating building conditions or exposure or by performing appropriate tests

Make necessary changes so that the problem will not recur

i = n-1 ?

Do results support your hypothesis? Attempt a control strategy

Collect additional information aboutbuilding occupantsthe HVAC systempollutant pathways

pollutant courcse (sample contaminants if needed)

Start (reason for concern)

Initial walk-throughpreparation

visual inspectiontalk with occupants and staffs

Follow-up validation

yes

yes

no

no

Prevention and control

• Source Management– Use of low emission products

• Carpet with low VOC and odor

• Furniture with low formaldehyde

• Electric cooker

• Source Treatment– scavenging coatings to treat HCHO

Contaminant control

• Ventilation– Natural

• Open window

– Mechanical: used in offices and commercial buildings• General dilution is used to dilution human bioeffluents and

other contaminants

• Used to mitigate SBS-type symptoms

• Guidelines on ventilation rate (CUM/person) for building designers

Contaminant control

• Air cleaning– Filtration to move particulate matter

• Dust-stop filters

• Pleated-panel filters

– Sorbents to remove gas contaminants• E.g., Activated carbon (charcoal) for VOC

A local study of indoor air pollution in offices and

public places in Hong Kong

• Study Period: October 95 - March 97 (18 months)

• Consultants: EHS Consultants Limited

• Contract Sum: HK$ 11 million

• Steering Group Members: SPEL, EPD, ASD, LD, EMSD, D of H

Objectives

• Characterizing and understanding the indoor pollution in offices and public places in Hong Kong.

• Assessing various causes of indoor air pollution and factors affecting IAQ.

• Identifying cost-effective mitigation measures and recommending control strategy.

Methodology

• Telephone questionnaire survey of 2000 office workers

• 40 representative office buildings selected for– on-site questionnaire survey (1183 respondents)

– detailed field measurements

• Public places - field measurements

• Country study• questionnaire design based on the one by the US NIOSH

• field measurement protocol based on the USEPA Building Assessment Survey & Evaluation (BASE) Study

Field measurements

Offices 40

Restaurants

Cinemas

Shopping Malls

Wet Markets

MTRC

20

5

8

2

2 stations/2 lines

Number of premises studied

On-site survey• Observations

• Sampling and Analysis: 5 sites per building, total 200

A. Physical B. Chemical C. Microbes D. VentilationTemperatureHumidityDraught

CO2, CO, NO2, O3, RSP, HCHO, Pesticides, Nicotine (ETS) VOCs:Benzene, Toluene, Xylene, Trichloroethylene, Chloroform, Carbon tetrachloride, Perchloroethylene, Dichlorobenzene

FungiGlucanBacteriaEndotoxinDust Mites

Air ChangeAir Flow RateAir Pressure

•Quality assurance•Independent audit•Outdoor parallel sample

Major Findings (1)

• Air quality of about 1/3 of the 1,500 office buildings in Hong Kong was perceived to be unsatisfactory or has violated relevant overseas standards.

Major Findings (2)

• Offices– 32% of the respondents dissatisfied with the IAQ of their workplac

e

– 90% had fresh air supply below minimum requirement of 7.51/s per occupant

– 37.5% had CO2, exceeded 1000ppm

– 32.5% had formaldehyde exceeded 100 µg/m3

– 20% had bacteria counts exceeded 1000CFU/m3

– 10% had the presence of toxigenic fungal species

– 10% had VOCs violated the relevant IAQ objectives

• Public Places– Occasional non-compliance including CO2, NO2, RSP and nicotine

Indoor Air Quality Management Programme in Hong Kong (suggested by the Study)

An inter-departmental IAQ Management Group has been formed to oversee the implementation activities, including:

• Launching public education campaign• Setting up an IAQ Information Center• Adopting IAQ objectives• Publishing Guide of Notes for the management of IAQ• Promulgating a IAQ certification scheme• Conducting review of legislative frame work for IAQ• Publishing professional practice notes for public transport facilities

Recommended indoor air quality objectives

Parameter Unit8-hr average (25oC and 101 kPa)

Level 1 Level 2 Level 3

Carbon Dioxide (CO2) ppm <800 <1000 <5000

Carbon Monoxide (CO) μg/m3 <2000 <10000 <29000

Respirable Suspended Particulates (RSP) μg/m3 <20 <180 -

Nitrogen Dioxide (NO2) μg/m3 <40 <150 <5600

Ozone (O3) μg/m3 <50 <120 <200

Formaldehyde (HCHO) μg/m3 <30 <100 <370

Total Volatile Organic Compounds (TVOC)

μg/m3 <200 <600 -

Radon (Rn) Bq/m3 <150 <200 -

Airborne Bacteria Cfu/m3 <500 <1000 -

Room Temperature oC 20-25.5 <25.5 -

Relative Humidity (RH) % 40-70 <70 -

Air movement m/s <0.2 <0.3 -• Level 1 : represents very good indoor air quality that a high-class and comfortable building should have.• Level 2 : represents indoor air quality that provides protection to the public at large including the very young

and the aged.• Level 3 : represents indoor air quality that is required to protect workers and employees as enforced under the

current occupational safety and health laws.

Indoor Air Quality Certification Schemefor Offices and Public Places

What is the "IAQ Certification Scheme"?

• The IAQ Certification Scheme aims to:– recognize good IAQ management practices– provide incentives for owners of premises /

buildings or property management companies to pursue the best level of IAQ

Why Participate?

• provide a good and healthy indoor environment

• improve the productivity and minimize medical expenses

• increase the competitiveness of the building

• enhance the corporate image

Key Features of the Certification Scheme

• Voluntary and self-regulatory approach• Two-levels of IAQ objectives • An IAQ certificate for display in the premises• Certify entire building or selected location(s) • The certificate is valid for 12 months • Measure a full set of parameters every 5 years • Need to maintain post-certification IAQ

Applicability

• Buildings or totally enclosed areas for use as offices or public places which are served by MVAC systems – office buildings– shopping malls– hotels & restaurants– theatres & cinemas– karaokes etc

Key Steps for IAQ Certification

• Step 1 : Engage a Competent Examiner

• Step 2 : Conduct Walkthrough Inspection

• Step 3 : Conduct IAQ Measurement

• Step 4 : Sign Off IAQ Certificate

• Step 5 : Apply for Registration

• Step 6 : Complete Registration

• Step 7 : Manage Post-certification IAQ

• Step 8 : Initiate Certificate Renewal