The term sick building syndrome (SBS) is used to describe situations in which building occupants experience acute health and comfort effects that appear to be linked to time spent in a building, but no specific illness or cause can be identified. Complaints may be localized in a particular room or zone, or widespread throughout the building.
In contrast, the term building-related illness (BRI) is used when symptoms of a diagnosable illness are identified and can be attributed directly to airborne building contaminants.
Studies suggest that a significant percentage of newly built or remodeled commercial and residential structures experience indoor air quality (IAQ) complaints. In warm, humid environments like Central Florida and Fort Lauderdale, problems frequently develop when mechanical systems are operated or maintained inconsistently with original design specifications or when building envelopes trap unwanted moisture.
Indicators of SBS vs. BRI
Indicators of Sick Building Syndrome (SBS):
- Building occupants complain of symptoms associated with acute discomfort, including headache; eye, nose, or throat irritation; dry cough; dry or itchy skin; dizziness; nausea; difficulty concentrating; fatigue; and sensitivity to odors.
- The exact cause of the symptoms is not immediately apparent.
- Most complainants report relief soon after leaving the building.
Indicators of Building-Related Illness (BRI):
- Occupants report specific symptoms such as persistent cough, chest tightness, fever, chills, and muscle aches.
- Symptoms can be clinically defined and have clearly identifiable diagnostic causes.
- Complainants often require prolonged recovery times even after leaving the building.
Complaints can also be influenced by factors such as acute allergies, job-related stress, or outside illnesses. Nevertheless, environmental investigations regularly confirm that physical indoor air problems exacerbate or directly induce these discomforts.
Common Causes of Sick Building Syndrome
1. Inadequate Ventilation
Modern building construction often seals building envelopes tightly to improve energy efficiency. However, when heating, ventilating, and air conditioning (HVAC) systems do not distribute sufficient outdoor air or fail to circulate air properly, indoor pollutants accumulate. Building standards developed by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) specify minimum outdoor air ventilation rates per occupant to preserve air quality.
2. Chemical Contaminants from Indoor Sources
The majority of indoor air contaminants originate from building materials and day-to-day operations. Adhesives, carpeting, manufactured wood products, office equipment, cleaning agents, and pesticides release volatile organic compounds (VOCs). Off-gassing from building materials or unvented combustion sources can elevate indoor pollutant levels quickly in closed environments.
3. Chemical Contaminants from Outdoor Sources
Outside air entering a property can introduce outdoor pollutants if air intake louvers are placed near vehicle exhaust zones, loading docks, plumbing vents, or commercial kitchen exhausts.
4. Biological Contaminants
Biological contaminants include mold spores, bacteria, pollen, and viruses. In Florida climates, these organisms frequently thrive where moisture collects: inside cooling coils, clogged condensate drain pans, humidified ductwork, and structural materials compromised by high humidity. When moisture issues remain unaddressed, licensed mold remediation may be required to correct microbial amplification on building materials.
Building Investigation Procedures
The goal of an indoor environmental investigation is to identify the source of complaints and establish practical corrective measures. A professional evaluation typically includes:
- Walkthrough inspection: A visual review of HVAC components, mechanical rooms, ceiling cavities, building layout, and occupied areas.
- Moisture & ventilation assessment: Measuring indoor relative humidity, temperature, airflow balance, and identifying areas susceptible to condensation.
- Targeted environmental sampling: When justified by visual findings or persistent occupant symptoms, conducting mold testing or air screening to evaluate indoor spore counts against outdoor baselines.
- Comprehensive property reviews: Scheduling a healthy home assessment to evaluate filtration performance, building pressure, and source pollutants.
Solutions to Sick Building Syndrome
Addressing SBS involves systematic source management and mechanical adjustments:
- Source Removal and Maintenance: Replace water-damaged materials, service air handlers, clean drain pans, replace air filters regularly, and allow new construction materials to off-gas before occupying spaces.
- Ventilation Adjustments: Verify outdoor air dampers are operational and calibrated to modern ventilation codes, ensuring balanced air distribution throughout all occupied zones.
- Exhaust Ventilation: Run dedicated exhaust systems in copy rooms, rest rooms, and janitorial closets to vent contaminants directly outside.
- Air Filtration: Utilize appropriately rated mechanical filters capable of capturing respirable particulates without overloading HVAC blower motors.