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Building Health Sciences - Healthy buildings, healthy people, healthy business

Medical Interviews Compliment Building Diagnostics

Quality tenants are extremely valuable in today's economy. Critical to their retention is the level of service and responsiveness provided by the property manager. Indoor environmental and air quality (IEAQ) issues can test the relationships among building owners, management, staff, and occupants. The objectives of each of these stakeholders may be very different. BHS responded on behalf of the building manager to a tenant request for an IEAQ investigation related to identification of any potential, building-related source of health complaints.


The building was conditioned by chilled water supplying VAV boxes and hot water perimeter radiant heat. The VAV boxes had the capability to re-circulate air from the ceiling space which is utilized as a return air plenum. In the ceiling plenum of this top floor space, there were numerous water-source unit heaters each with individual thermostats for temperature control. Design intent, apparently, was to condition the plenum to offset the impact of the flat roof directly above on air temperature in the ceiling plenum.

The office space had been completely refurbished by the tenant two years prior to the inspection. During that effort, demolition of existing walls and layout configurations occurred prior to build back in the renovated configuration. The tenant had occupied its offices throughout the construction process.

BHS performed a visual inspection of the tenant space and associated mechanical equipment room for the air handling unit. The offices presented as “like new”and in pristine condition. Ceiling tiles were lifted in different locations to inspect the condition of the ceiling plenum. The ceiling plenum had a moderate to high film of dust on all horizontal surfaces, along with demolished construction debris and used pieces of ceiling tile. There was a light film of white dust throughout the occupied perimeter office space. Dust was light but apparent on top of cubicle dividers. Dust was very heavy on high surfaces in offices and on door frames in some locations. Dust accumulation on door frame headers, which appeared to be construction dust, had not been cleaned since the tenant's reconstruction activities.

BHS' physician privately interviewed a number of employees who had reported health effects they attributed to the indoor environment. Each had completed our “Occupant Diary” form, chronicling the complaint, the location and its severity, with additional observations. These were reviewed. All concurred that symptoms did not occur in the reception area or the adjacent small conference room, although they did so throughout the rest of the space. The reported symptoms (primarily sneezing, but also coughing, red, irritated eyes, upper airway congestion) were all consistent with airborne dust. Particle counts were elevated.

BHS determined that dust in the ceiling plenum was regularly disturbed through the intermittent operation of the fan-powered unit heaters. This, in conjunction with recirculation of return air in the ceiling plenum by VAV box operation into occupied space, distributed airborne dust particles in the occupied space, evidenced by deposits on horizontal furniture surfaces. This airborne dust, specifically mapped to the areas of deposit and air handling unit coverage, was the cause of the reported irritant symptoms, including sneezing, coughing and mucous membrane irritation.


The four elements involved in any IEAQ situation, Source, HVAC System, Pathway and Occupants, are demonstrated by this incident. Through our parallel investigation of both the occupants' health-related complaints and the building conditions, we determined that the absence of symptoms in the reception area and small conference room combined with no evidence of dust (1 – SOURCE) above these areas, which were served by a separate air handling unit (2 - HVAC SYSTEM), confirmed the source of discomfort was residual construction dust moved through the ceiling plenum (3 – PATHWAY). The disappearance of symptoms when tenants walked from one air handling unit's coverage area to another served as confirmation. Additionally, no work had been performed in the lobby area and there was no dust deposited in the ceiling plenum. The remainder of the tenant space, the tenant complaint area (4 – OCCUPANTS), was served by a single air handling system described previously, which had been in operation during the renovation.

In order to avoid IEAQ problems, any one of these four elements must be removed or interrupted. Failure to consider preventive measures prior to the initiation of interior renovations created the pollutant source. Steps taken to prevent IEAQ problems include:

  • Ensuring that the IEAQ Manager reviews the design, sequencing and planned construction activities for all proposed remodeling or renovation activities, prior to their initiation;
  • Scheduling work during periods of low occupancy;
  • Isolating work areas by blocking return vents in the work area and/or installing temporary, containment-like, barriers;
  • Pressurizing spaces that adjoin the work space, in order to prevent transportation of pollutants;
  • Using specialized high cleaning procedures (e.g., HEPA vacuums);
  • Protecting the air conveyance system throughout the life of the project;
  • Changing filters more frequently, especially after work is completed;
  • Minimizing emissions from materials processes (e.g., wet sanding dry wall), and
  • Buying and utilizing green products to the maximum extent possible.

Unless remodeling and renovation are planned with IEAQ's shared responsibility in mind, these activities can create problems by emitting dust, odors, microorganisms and their spores, endotoxins and VOCs. Building occupants, staff, and management must share the goal of providing a healthy indoor environment by planning ahead and considering the consequences of their most well-intentioned actions.

Dust Zone