standard for minimum ventilation rates and indoor air quality that will be acceptable to human occupants and avoid adverse health effects. Key issues in evaluating HVAC include: ● Are ASHRAE standards followed? ● Is the ventilation system properly maintained and operated? ● Can the HVAC system control existing contaminants and ensure thermal comfort? ● Are the pressure relationships maintained between areas of the building so that the air- flow goes from cleaner areas to dirtier areas? Inadequate ventilation may occur when insufficient air exchanges are made if air supply and return vents within each room are blocked or placed in such a way that outdoor air does not reach the breathing zone by improperly located outdoor air-intake vents and by spreading biological contaminants that have multiplied in cooling towers, humidifiers, dehu- midifiers, air conditioners, or on the inside surfaces of ventilation ductwork. 2. Observation of production processes and work practices. It is important to notice whether PPE and clothing are being used appropriately. Review equipment maintenance schedules to ensure that they are being followed. 3. Measurement of contamination levels and employee exposure. Area and personal sampling for contaminant exposure should be conducted periodically when applicable. This also pro- vides verification that control measures are working properly. 4. Use of appropriate control measures. Engineering controls, particularly ventilation and air treatment, will help prevent or alleviate many IEQ problems. Administrative and work prac- tice recommendations also are useful. 5. Education of workers and management about IEQ and the factors that affect it. Education is essential for all workers to understand what factors affect air quality and what they can per- sonally do to improve environmental work conditions. Individuals react very differently to exposure to indoor air pollutants. Secondary Prevention An environmental air quality investigation begins when an employee(s) has a complaint or symptoms. 1. Identification of pollutant sources. Commonly found office pollutants and their sources include environmental tobacco smoke asbestos from insulating and fire-retardant building supplies formaldehyde from pressed-wood products other organics from building materials, carpet, and other office furnishings cleaning materials and activities restroom air fresheners paints adhesives copying machines photography and print shops biological contaminants from dirty ventilation systems or water-damaged walls, ceilings, and carpets and pesticides from pest-management practices. Consider whether the source of contamination or discom- fort occurs indoors, outdoors, or within the mechanical systems in the building. See pages 265–266 for a list of major indoor air contaminants. Background information on the building, such as age, type of construction, ventilation system design, and history of renovations and repairs should also be gathered. Professional judgment must be used to determine whether samples should be collected to evaluate potential sources and potential contaminants. Based on these findings, further investigations may be performed. 2. Employee interviews. Conduct a symptom history, including specific complaints and associ- ated symptoms when symptoms occur (season, time, days, frequency) where they occur how long symptoms last if they clear up after leaving work (and how soon) if symptoms have been triggered by any specific event or in any specific area what is the source of symptoms and if any medical care was given or diagnosis made. 3. Review of records of health tests, job histories, and injuries and illnesses. Review worker characteristics, such as smoking history, allergies, pre-existing illnesses, medication use, and any occupational contributors. 4. Health testing or physical examinations. Consider health testing and/or physical examina- tions based on pollutant sources and symptoms reported. Due to the very complex nature of indoor air sampling, unless a specific candidate contaminant has been identified, health test- ing may not be particularly useful. 264