1.  INDOOR AIR QUALITY AND HEALTH

"Since I started working in this office I have been tired and have had so many colds and sinus infections.  I never used to be sick so much."

HEALTH

"I get headaches at work and am really tired but I begin to feel better as soon as I leave the building.  Over the weekend I feel fine."

Among the symptoms commonly identified as related to indoor air quality are:
· headache · fatigue · frequent colds or sinus infections
· sore throat · dry skin or rashes · dry or irritated eyes
· sinus congestion   · irritation of the mucous membranes

These symptoms are no different that those of many common illnesses like colds and flu.  What might be different are the following:

Place: Almost everybody, or almost everybody in a particular area seems to have similar problems.
Time:  People are only sick at work and feel better in the evenings and weekends.
Changes: The onset of symptoms may be associated with some change in the working conditions, like moving to a new or different building, using different equipment, or renovating the building.

WHAT CAN BE DONE ABOUT IT

ãEver since we moved into the new building people have been complaining of rashes, itchy eyes, and sore throats.  This building is not a healthy place to work.ä

There is no particular treatment for the illnesses that are associated with indoor air quality problems.  Sometimes a trial period away from work can help to diagnose the cause.  Medically the doctor can help you treat the symptoms, but changes at the workplace may be necessary to cure and prevent symptoms.

The majority of people improve when measures are taken at the workplace to reduce sources of airborne contaminants, increase fresh air, or improved temperature and humidity control.  Some recover rapidly, some much more slowly. Indoor air symptoms do not appear to progress to other diseases.

See other fact sheets below on 2. Evaluating Indoor Air Quality Problems and 3. Improving Indoor Air Quality and 4. Ventilation
 

2.  EVALUATING INDOOR AIR QUALITY

What can cause health problems in an office building?

1. Contaminants.  Contaminants may come from inside or outside the building.  Indoor sources of contaminants include cigarette smoke, renovation and remodeling materials, dirt, deteriorating lining in the ventilation system itself, cleaning compounds, materials that are used inside such as white-out, copy machines, laser printers, pesticides, etc.  Outdoor sources include car exhaust, pollen, and industrial emissions from nearby buildings.

Any water leaks are also of concern because molds can find hospitable growth conditions in damp carpet, wallboard or ceiling tile.

2. Ventilation.  The other very important determinant of indoor air quality ventilation.  The ventilation system should bring fresh air to all occupied spaces and remove contaminants that occur in normal use.  An evaluation includes determination of how much fresh air is being provided and the quality of that fresh air.  It should address how well the distribution system is functioning to ensure that all areas are getting adequate fresh air and feel very stuffy much of the time.  The air system must be balanced and assure good mixing.

No evaluation is complete without a look at the fresh air intakes.  Is there really outside air entering the system or have louvers been closed or blocked off.  If the air is coming in, is it fresh or is it potentially contaminated by nearby industrial discharge, perhaps a loading dock where trucks idle or nesting birds some other source of pollution.

Extensive and expensive measurement is not the way to go.

Sometimes measurements of carbon dioxide and total airborne hydrocarbons (VOCs) are taken to help determine the adequacy of the ventilation in maintaining good air quality.  If the air circulation is poor and the fresh air insufficient, carbon dioxide, which derives primarily from people breathing, builds up.  The carbon dioxide is not itself hazardous, but is used as a marker of a lack of fresh air and good ventilation.  (Note that if only a few people work in a large area, carbon dioxide may not be a good indicator because there is not much breathing going on.)  Additional measurements of many different potential contaminants can be expensive and add little information to the evaluation.

Carbon dioxide (CO2)  Test results are almost always low when compared to an OSHA standard that was set for industrial environments, and is based on the potential toxic affects of the gas itself.  For example, the OSHA standard for carbon dioxide is 5000 parts per million (ppm), but it is recognized that when indoor levels rise above 700-800 ppm, building occupants report discomfort. Carbon dioxide is often the only useful measure taken and can provide useful information if done properly.

Odors   Your nose can be an important qualitative measurement device.  For example, if vehicle exhaust enters the building carbon dioxide (as well as carbon monoxide) levels will increase.  Vehicle exhaust is accompanied by an odor which people are quick to recognize and complain about.  Smoking contributes to both carbon dioxide and total hydrocarbons levels in the air.

Total volatile hydrocarbons can be measured as an indication of the overall adequacy of the ventilation.  This test would pick up traces of cleaning chemicals, perfumes, exhaust, paints, art materials, cigarette smoke, carpet glues, etc. As with carbon dioxide, OSHA standards for industrial environments for many of these same hydrocarbons found in trace levels in office air are several hundred times higher.  There is no national standard for the indoor environment, either office or school.  For the Scandinavian countries a level of less than 0.5 mg/m3 is recommended although often exceeded.  VOCs are not routinely measured as measurements vary considerably with method of used and type of concurrent activity.  If a source is obvious, steps should be taken to reduce it rather than measure it.

Particulates, airborne dust particles, are a common problem in office and school environments.  Potential sources of particulates in the air include old and/or dirty carpeting, paper dust, chalk, outside dirt that gets tracked in, and other dirt from habitation and work. If ventilation filters are overloaded or breached, or some part of the structure (sometimes the insulation of the ductwork) deteriorates, the ventilation system itself can become a source of contamination.  It is not unusual for construction dust to get into the ventilation system.  Systems designed with an open return plenum are especially susceptible.

If the filters are changed regularly and the system is intact and functions well, routine cleaning of the duct work should not be necessary.  Evidence of dirt around the air supplies on the ceiling indicates an excess of room dirt that is caught there by static electricity caused by the air flowing.  It is not due to dirt in the ductwork itself.

3. BIOAEROSOLS. Levels of airborne mold or bacteria or their by-products are sometimes measured.  The most common measurement is of viable airborne mold levels, the spores that will grow if they out on a agar petri dish.  These results have NOT been shown to correlate with symptoms.  Mold is always present in indoor as well as outdoor air and varies tremendously both seasonally and from place to place.  A visual inspection for evidence of water damage, a history of leaks,  or chronic dampness is often more useful than measurement in determining the potential for mold.

For comfort good temperature control and relative humidity levels between 30 and 50 % are recommended.  Levels below 30% indicate air that may be dry enough to be irritating to mucous membranes.  Air that is too humid, RH greater than 60%, may cause moisture to form and mold to grow.

In most cases, a few simple measurements and a close look at the environment and ventilation system provides enough information about what kinds of changes need to be made to improve the air quality. This kind of qualitative investigation points the way to improving the air quality and the health of the workers in the building.
 

3.  IMPROVING INDOOR AIR QUALITY: SOURCE REDUCTION

Overview

Energy conservation was strongly emphasized in the 1970âs, following the oil crisis.  The need to conserve energy led to reduced ventilation rates.  Buildings were sealed to exclude hot summer air and cold winter air.  Computers and other office technologies led to more heat output, chemical hazards, and job stress.

By 1988, The National Institute for Occupational Safety and Health (NIOSH) found that over 20% of its calls were about indoor air quality.  Of the over 500 investigations done by NIOSH, over 50% had a primary problem of inadequate ventilation.  The next most common findings were inside contamination (15%), outside contamination (10%), and building materials themselves (4%).

What kinds of things can be done?

Inside Source Reduction

For example:
· Sometimes cleaning compounds are used in higher concentrations than are recommended by the manufacturer resulting in irritating vapors.   Recommended dilutions should be used.

· Carpets in heavy traffic areas can retain dust and chemical residues.  More frequent vacuuming, with appropriate filters, is helpful in reducing dust levels.  Carpet shampoos themselves can be a source of contamination.

· Pesticides should only be applied when the building is unoccupied. Offices should be thoroughly ventilated before workers return to the building.  Use of less toxic pesticides such as boric acid for cockroaches may be appropriate.

· If smoking is allowed, separate well-ventilated areas should be provided for that activity.

· Equipment that generates contaminants such as photocopiers and laser printers should be equipped with local exhaust ventilation so that the contaminants that they generate do not get into the general ventilation system and spread throughout the building.  Carbonless copy paper and white-out (water-based is OK) can sometimes cause problems.

Outside Source Reduction

For example:
· Fresh air intakes should not be located near sources of air contamination such as loading docks where trucks may idle, or near parking lots, or dumpster storage. Ventilation intakes should not be located downwind of air exhausts or other sources.  Intakes or exhausts may need to be relocated or to have air cleaning equipment installed.  Fresh air must be clean.

· Construction (or demolition) such as roofing or paving, office renovation such as knocking down walls, laying carpet, painting, etc can create fumes or dusts.  This work should be done with proper controls when the offices are not occupied.

Control of Microbial Contamination

For example:
· Most frequently, microbial amplification follows water damage to carpets, ceiling tiles and walls, or furnishings, or standing water in the ventilation system.

· Any spills or leaks must be cleaned up promptly. to prevent mold.  If carpet, ceiling tiles or other porous materials have become saturated with water, they should be dried within 48 hours.  If this is not possible, wetted sections should be discarded and replaced rather than disinfected.

· Non-porous surfaces where moisture has collected can be cleaned and disinfected with detergents and bleach solutions.

· Drip pans in air condition units should be kept clean and well-drained.  Coiling coils should be regularly inspected for cleanliness.

· Humidification may be needed to prevent excessive dryness, but moisture can favor microbes that cause disease.  Additives to kill microbes can cause respiratory irritation.  For central humidification, dry steam systems are recommended.  For smaller units, fanatic attention to cleanliness is crucial.
 

4.  IMPROVING VENTILATION IN OFFICES AND SCHOOLS

HVAC SYSTEMS

In houses and some very old buildings you still find radiators for heat, and windows for ventilation and cooling.  Most modern office buildings have replaced radiators and openable windows with heating, ventilating, and air conditioning (HVAC) systems.  These systems consist of ductwork to transport air and fans to push or pull it through the ductwork.  The openable windows have been replaced by dampers or louvers on the fan housings which open to bring some fresh air into the system.  A thermostat calls for heating or cooling to maintain the temperature.  The air is transported to all the rooms through the ductwork and blown into each room through the diffusers to both ventilate and maintain the desired temperature.

The ventilation system is very important to how you feel when you work in the building as well as to whether you are warm enough or cool enough.  The perfumes and shampoos that people wear, the materials that we use in very small amounts like whiteout or glue, residues from cleaning compounds, the new furnishings and carpeting, even our exhaled breath impacts the air around us.  We need the ventilation system to keep the levels of these contaminants, byproducts of normal routine, to a minimum.  This is done by constantly bringing in fresh air and removing stale air.  For particular sources of contamination like a heavily used photocopy machines, we cannot depend on this "general" ventilation system but should have a local exhaust system which takes the pollutant away before it can get into the air which surrounds us and recirculates.

FRESH AIR INTAKE

Air enters the building through the outdoor air intake.  This may be on the roof in a roof-mounted unit or it may be in the wall of the fan room.  Amounts of air coming in are usually controlled by dampers which can be adjusted to take in more or less air depending on the outside temperature.  In order to get adequate ventilation, the dampers should be adjusted so that they can never completely close.  A minimum setting which allows for 25% of the air to be outdoor air is recommended.  (Since the energy crisis, the start of indoor air quality problems in many buildings, air intakes have been set to take in 10% or less to save on heating and cooling costs.)

Common problems with intakes:
· There are none.  No fresh air is coming in.  There should be at least 20 cubic feet per minute (cfm) of fresh outside air per occupant coming into each space.
· The intake is poorly located and brings in contaminated air.
· The intake dampers are sealed shut.
· Pigeons are roosting in the fresh air intake.

FILTERS

This fresh air mixes with air returning from the rooms and this mixture then passes through one or more filters.  The first filter will usually be a fiberglass filter that catches leaves and feathers and large dust.  Small particles or fine dust may pass right through as will gasses like car exhaust fumes.  There may be other filters to catch finer dust or even to catch volatile organic carbons (VOCs) but often there is just one filter for large particles.

Common problems with filters:
· The filters are not changed regularly or often enough.  Should be done at least quarterly.
· The filters are not the right type to remove contaminants that are coming in.

FANS

The fans with their motors move the air.  If they do not have sufficient capacity they will not bring in enough air.  If the fan is not working properly the air doesn't move, or not enough of it moves.

Common problems with fans:
· Fan belts are broken or slipping, fan blades corroded, motors burned out
· Additions have been made to the system but the same fan is still trying to run it and is not strong enough.

DUCTWORK, DIFFUSERS AND RETURNS

The air is forced by the fans along the ducts to the diffusers which allow the air into the room.  Within the room the air should mix thoroughly so that the temperature is the same throughout the room and fresh air mixes in.  Good mixing is essential for good temperature control as well as freshness.

The air should then leave the room through the return.  They may look similar, but the air comes in through the diffuser and leaves through the return.  Use a piece or tissue paper to test these.  The tissue should stick to the surface if the air is being drawn out and wave if the air is blowing into the room.

Common problems with ducts and diffusers and returns:
· The ducts have been damaged and are no longer connected to the fan.
· The ducts are lined on the inside with fiberglass which is breaking down -The ducts may have accumulated large amounts of dust or have become damp and grown mold or bacteria which is then distributed with the air
· The ducts are delivering more air to the rooms that are close to the fan and much less to the rooms that are at the end of the line.
· Some rooms lack diffusers or returns completely because walls and partitions have been changed but the ventilation system was never changed.
· Diffusers have been blocked off, often to change temperature.
· Returns have been blocked, often thoughtlessly, by furniture and stuff.
· Proper air mixing is not occurring because diffuser and return are close together and the air goes straight from one to the other.
· The return air does not have a duct to carry it but passes instead through the open space above the dropped ceiling.  Whatever is up there, asbestos, pigeons or former pigeons, is swept right into the HVAC system and recirculates.

TEMPERATURE, HEATING AND COOLING

Somewhere in the system, usually near the fan the will be the means of heating or cooling the air.  The cooling system is usually some metal coils containing chilled water or a refrigerant which are inside the duct.  The air passes over these cold coils and is cooled.  The air also leaves some moisture in the form of condensation on the coils.  There should be a pan underneath to catch the drips and the pan should have a drain so that it does not accumulate water.  Some form of heat like an electric heater or hot water coils or other heated surface may also be found inside the duct to heat the air when necessary.  The air may also be humidified for comfort in the winter.

Relative humidity affects comfort.  The official comfort range is between 30 and 60 percent with temperatures between 68 and 80oF.  This doesn't work for everyone.

Potential problems with the heaters and coolers:
· Water accumulates in the condensate drip pan, mold grows, and gets into the air.
· The heating or cooling coils get dirty, cutting down air flow and adding dirt to the airstream.
· Refrigerant can leak into the air system
· Flue gas, products of combustion, can leak into the air system.

THE WHOLE SYSTEM

Some types of systems, called variable air volume (VAV) systems, have extra thermostats and dampers above the diffusers.  If a room or group of rooms is already at a satisfactory temperature, the dampers will close and not allow that room to get any more air.  Others will have a constant flow of air but vary the mixture between return and fresh or the use of heat and cooling.

Common problems with the whole system:
· It is turned on and off by a timer and starts at, say 8, turns off at, say, 5 and people who work other hours have no ventilation.
· Nobody knows where the components of the HVAC system are or how it works.
· No one has checked it since 1948.  The last time it was balanced was when the building was built and many changes have occurred since then.

STANDARDS, NORMS GUIDELINES

Carbon Dioxide:  Fresh outside air normally contains between 250 and 400 ppm of carbon dioxide depending on the amount of traffic in the area.  In general, a level of about 700 ppm has been found to be associated with the onset of the complaints.

Fresh Air: The American Society of Heating, Ventilating, Refrigerating and Air Conditioning Engineers (ASHRAE) recommends that a minimum of 20 cubic feet per minute (cfm) of fresh outdoor air be provided in offices for each occupant, 15 cfm per occupant for classrooms.  Any additional sources of air contaminants, printers, copiers, chemical usage will increase the need for  fresh air unless local exhaust ventilation is used.