(IAQ)

History of Indoor Air QualityGreek philosophers, 500 BC, concerned with air quality in

mines

Roman, Pliny the Elder, advised masks for stonecutters and asbestos miners

Early 1800s, first recommendations for ventilation standards to control odor

Florence Nightangle(1858) recommended air exchange rate of 25 cfm/person to avoid re-infection in hospitals

Questions Regarding Indoor Air QualityWhat is Indoor Air Quality?What is the relationship between indoor and outdoor air

quality?Why should you be concerned about the quality of air that

you breath?What causes indoor air problems?What are the factors affecting indoor air quality?How does outdoor air enter a house?What are the health effects from indoor air pollutants?Can you give examples of indoor air contaminants?Do you know the origin of air quality problems?What are the guidelines for IAQ?What is an IAQ prediction model?What are the strategies to improve indoor air quality?

What is Indoor Air Quality ?Refers to good and bad effects of the contents of air inside

a structure on its occupants

Good indoor air quality(IAQ) has no unwanted gases or particles in it at concentrations which will adversely affect someone

Poor indoor air quality has gases or particles in excessive concentration so as to affect the satisfaction or health of occupants

Relationship between Indoor and Outdoor Air Quality

Indoor pollutant concentrations may be higher or lower than outdoor air concentrations

Outdoor contaminants may be present indoors at a sufficient concentration to affect the occupants

Example : Pollen and mold spores from outdoors causes

hay fever and allergies indoors

Why should you be concerned about the quality of air that you breath?

The contaminant indoor air could damage people’s health

Indoor air pollutants are among the top five environmental risk

People spend about 90% of their time indoors and so the health problems that result from exposure to indoor pollution increases

According to World Health Organization (WHO) approximately 30% of all commercial buildings have significant IAQ problems

Statistics on Indoor Air Pollution

Indoor radon exposure is estimated to be the second leading cause of lung cancer (American Lung Association )

Environmental tobacco smoke (ETS) causes an estimated 3,000 lung cancer deaths and 35,000 to 50,000 heart disease deaths in non-smokers, as well as 150,000 to 300,000 cases of lower respiratory tract infections in children under 18 months of age each year (ALA)

1.4 million buildings in the United States have indoor problems (OSHA)

Legionnaires Disease strikes 25,000 people and kills over 4000 people every year (Center for Disease Control)

Sources of PollutantsNormal Biological Processes - people and pets generate

carbon dioxide, moisture, odors and microbesCombustion appliances such as wood stoves, gas stoves,

furnaces, fireplaces and gas heatersUse of consumer products such as spray cans, air

fresheners, spray cleaners and construction materialsCigarette smokingSoil under and around buildingsAppliances such as humidifiers, air conditioners and

nebulizers

Sources involved in IAQ problems

Problem Origin Percent Typical Sources

Inadequate Building Ventilation Systems

53%Lack of outside air, poor air distribution, uncomfortable temperature and humidity, contaminant sources inside the system

Contaminants Originating Inside Building

15%Solvent vapors, dusts, formaldehyde, building materials, furnishings

Building Products 4% Concrete, wood, furnishings.

Unknown Causes 13% Unidentified sources

Outdoor Contaminants Entering Building

10%Motor vehicle exhaust, pollen, fungi, smoke, construction

Microbiological Agents 5% Bioaerosols, Legionella

Evaluations by National Institute for Occupational Safety and Health (NIOSH) for studies on more than 500 Indoor Air quality health hazard cases

Reasons of IAQ Problems based on NIOSH study

Inadequate Ventilation

53%

Bioaerosols5%

Outside Contamination

10%

Building products

4%

Unknown causes

13%

Inside contamination

15%

Factors affecting IAQMeteorological conditions

Ventilation condition

Pollutant decay

Pollutant removal

Pollutant release

Permeability of structures

Outdoor air quality

How does Outdoor Air enter Indoors

Infiltration - outdoor air flows into the house through openings, joints, and cracks in walls, floors, and ceilings, and around windows and doors

Natural Ventilation - air moves through opened windows and doors

Mechanical Ventilation - from outdoor-vented fans that intermittently remove air from a single room, such as bathrooms and kitchen, to air handling systems that use fans and duct work to continuously remove indoor air and distribute filtered and conditioned outdoor air to strategic points throughout the house

Health effects due to Indoor Air Pollutants

HeadachesNauseaRespiratory infectionsAsthmaHypersensitivity pneumonitisHumidifier feverLegionnaire’s diseaseLung cancer

What is Sick Building Syndrome (SBS)?

Condition of a building in which more than 20% of the occupants are suffering from adverse health effects but with no clinically diagnosable disease present

It is a condition of a building ; not of the occupants

It takes place due to long term exposure to low levels of contaminants

 

SYMPTOM POSSIBLECONTAMINANTS

PRIMARYSOURCES

ENVIRONMENTALCONDITION

· Headache · Fatigue · Poor Concentration · Dizziness · Tiredness

· Bio-aerosols · VOCs

· Ventilation systems · Humidifiers · Drip pans · Cooling coils in AHVs · Plants · Outside air

· Ergonomic Conditions · Noise and Vibration

· Headache with nausea · Ringing in ears · Pounding heart

· CO · Formaldehyde

· Incomplete Combustion (vehicle Exhaust, stoves, fireplaces) · Building products · Furnishings

· Ergonomic Conditions · Noise and Vibration

· Dry Throat · Shortness of breath or Bronchial Asthma · Irritation and Infection of Respiratory Tract

· NO2

· Formaldehyde · VOCs · Particulates

· Incomplete Combustion · Building Products · Furnishings · Smoking

· Relative humidity

    Health Symptoms and Possible Contaminants

Health Symptoms and Possible Contaminants

SYMPTOM POSSIBLECONTAMINANTS

PRIMARYSOURCES

ENVIRONMENTALCONDITION

· Nasal Problems (Stuffiness,Irritation)

· NO2

· Formaldehyde · Bio-aerosols

· Incomplete Combustion · Building Products · Furnishings · Ventilation Systems · Humidifiers · Drip Pans · Cooling Coils in AHVs · Outside Air

· Relative Humidity · High Temperatures

· Skin Problems (Dryness, Irritation, Rashes)

· Formaldehyde · Ventilation Systems · Humidifiers · Outside Air

· Warm Air · Low Relative Humidity · Excessive Air Movement

· Eye Problems (Burning, Dry Gritty Eye)

· NO2

· Formaldehyde · VOC's · Particulates · Bio-aerosols

· Incomplete Combustion · Building Products · Furnishings · Ventilation Systems · Humidifiers · Cooling Coils in AHVs · Outside Air · Building Product Deterioration

· Artificial Light

List of Pollutants affecting IAQVolatile organic compounds (VOCs)

Dust and dirt

Radon

Bio-aerosols

Environmental tobacco smoke (ETS)

Respirable Particulate Matter (RPM)

Carbon and Nitrous Oxides

Origin of Indoor Air Quality Problems

Inadequate ventilation

Pollutants from material processed inside the building

Pollutants drawn in from outside air

Biological contamination

Pollutants from building materials and furnishings

Saving energy

POLLUTANTCONCENTRATIO

NREMARKS

• Asbestos • 40 CFR• 0.2-2

fibers/cucm 

• EPA• OSHA Standard (8hr

TWA)

• Carbon Dioxide

• 1000 ppm  • 5000 ppm 

• ASHRAE Standard • Ministry of Labor

Standard(TWAEV)

• Carbon Monoxide

• 9 ppm • 50 ppm   • 9 ppm  • 35 ppm 

• EPA• OSHA Standard for 1hr• ASHRAE-Average over 8

hr• NIOSH standard for 1hr

Guidelines for IAQ pollutants

POLLUTANT CONCENTRATION REMARKS

• Formaldehyde • 0.4 ppm • 0.75 ppm 

• ASHRAE Standard • OSHA (8 hr TWA)

• Nitrogen Dioxide

• 5 ppm• 3 ppm 

• 0.053 ppm

• OSHA• Ministry of Labor Standard

(TWAEV) • Annual National Ambient Air

Quality Standard (USA)

• Ozone • 0.05 ppm• 0.1ppm• 0.08 ppm 

• WHO• OSHA (8hr TWA)• WHO-Criteria Document

• Particulates • 260 µg/cum 

• 150 µg/cum 

• National Ambient Air quality Standard-24 hr geometric mean

• EPA, 24 hr annual geometric mean 

Guidelines (contd.)

POLLUTANT CONCENTRATION REMARKS

• Radon • 4 picoCuries/L • 4 WML radon

progeny calendar year 

• ASHRAE Standard • Mine Safety and Health

Administration

• Volatile Organic Compounds (VOC)

• 1-5 mg/cum

• 3 mg/cum

• US Environmental Protection Agency Guidelines

• Molhave, 1990

• Microbial fungi

• <50 CFU/cum • <150 CFU/cum • <500 CFU/cum

• 2 Species • 3 Species • Agriculture Canada Standard

Guidelines (contd.)

What is an IAQ Prediction Model?

It is basically a Mass Balance EquationThe equation is

(Pollutant flowing) – (Pollutant flow out)

+ (Source emissions) – (Sink removal)

= Indoor air pollution accumulation Units are mass/time

Strategies to improve Indoor Air Quality

Pollutant Source Control

Increased Ventilation

Dehumidification

Use of Air Cleaners Dust collectorsFilters