• Purpose - Remove or dilute airborne contaminants

• Supply air - mixture of outside air and re-circulated air

VENTILATIONVENTILATION

dilution ventilationdilutes

contaminant to an acceptable level

comprises fans set in walls or roof

cheap and simplelimited application

as a control strategy

local exhaust ventilationcaptures

contaminant close to point of generation

comprises hood, ductwork, filter, fan,outlet

good control of hazardous contaminants

VENTILATIONVENTILATION

changes the whole workplace air over a given time period ie air changes per hour

limit to circumstances where:exposure limit is highlow evaporation rate for liquidsslow evolution for gasesoperators not close to the point of

generationsubstance is quickly carried away from the

operator

DILUTION VENTILATIONDILUTION VENTILATION

rate of contaminant generation governs air changes per hour required

density of contaminant governs position of fans:density >1 (ie solvents) - low level fan in

walldensity <1 (ie hot gases) - high level fan in

roofproblems include:

“dead areas” where poor airflow allows contamination to build up

heat losses due to high rate of air change

DILUTION VENTILATIONDILUTION VENTILATION

Hood or exhaust inletreceptor hood

contaminant directed into a large hood by fan assisted draught

captor hoodcontaminant captured by air flow close to

point of generationlow pressure large volume flowhigh pressure low volume flow (high

velocity)

LOCAL EXHAUST LOCAL EXHAUST VENTILATIONVENTILATION

ductingstraight with gentle bends and angled jointssufficient air flow to prevent deposition of

solidsaccess ports for cleaning and flow

monitoringfilter or purifying system

cyclones, washers, electrostatic, bag filters

LOCAL EXHAUST LOCAL EXHAUST VENTILATIONVENTILATION

Fansaxial flow fan

airflow is parallel to the shaft of the impeller

compact and fits neatly into ductwork centrifugal fan

air enters the impeller then is discharged at right angles

exhaust outletcareful location to avoid:

cyclic pollutioneffects of weather of air disturbance

LOCAL EXHAUST LOCAL EXHAUST VENTILATIONVENTILATION

• Componentso Air intakes, dampers, filterso Heating & cooling units, coils, drain panso Ductworko Supply ventso Exhaust ventso Plenum

HAVC SYSTEMSHAVC SYSTEMS

• Poorly balanced systems

o Areas with stale air

o Drafty areas

o Contaminant buildup

o Uncomfortable temperatures

o Odors from other areas of the building

WHEN GOOD HVAC SYSTEMS GO WHEN GOOD HVAC SYSTEMS GO BADBAD

• Excessive dust and dirt in the supplied air

• Insects

• Mold spores

POOR FILTERS OR POOR FILTER POOR FILTERS OR POOR FILTER MAINTENANCEMAINTENANCE

• ASHRAE Standards

• Temperature

• Relative Humidity

• Minimum outdoor air requirements

• CO2 levels below 1000 ppm

• Outdoor air supplied at 15 cfm/person

VENTILATION TO MEET VENTILATION TO MEET OCCUPANT NEEDSOCCUPANT NEEDS

• Modify ventilation system

• Modify pressure relationships

• Filters

• Ion generators

• Humidification systems

VENTILATION – ENGINEERING VENTILATION – ENGINEERING CONTROLCONTROL

INDOOR AIR QUALITYIndoor air can contain vapors from cleaning

products, building materials, carpet, furniture, combustion sources, photocopiers, fax machines, and particulates like dust, dirt, pollen, mold, bacteria, and many other types of particles and pesticides brought in from outdoors or generated indoors.

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

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 PollutionIndoor 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 microbes

Combustion appliances such as wood stoves, gas stoves, furnaces, fireplaces and gas heaters

Use of consumer products such as spray cans, air fresheners, spray cleaners and construction materials

Cigarette 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 ContaminantsSYMPTOM POSSIBLE

CONTAMINANTSPRIMARYSOURCES

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 dirtRadonBio-aerosolsEnvironmental tobacco smoke (ETS)Respirable Particulate Matter (RPM)Carbon and Nitrous Oxides

Origin of Indoor Air Quality ProblemsInadequate 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.)

A healthy indoor environment is one which the surroundings contribute to the productivity, comfort and sense of health and well being.

A healthy environment may be achieved by proper building maintenance and communication.

SUMMARYSUMMARY

…….Thank You………