We often come across situations where interior renovation projects must be performed in areas adjacent to occupied spaces or other sensitive areas. These types of projects usually require work that can produce excessive airborne dust and noise which, if not properly managed, can disrupt operations and affect productivity of employees working nearby. This particular discussion focuses on managing dust, though the approaches suggested can also be useful for managing noise issues.
Renovation activities such as concrete chopping/cutting/coring, sheetrock demolition, and dry sanding of joint compound during installation of new sheetrock can generate elevated levels of airborne dust. Proper planning and monitoring can help to avoid complaints from those employees working in adjacent areas (likely resulting in project delays and added costs), migration of construction dust to other areas through HVAC systems, and possible exposure hazards to employees.
Suggested planning should include establishing work practices and employing engineering controls during the project to minimize generation and migration of dust. Potentially affected employees, including those working directly in the renovation zone and those in adjacent areas, should be notified of this information in advance of the work, including a description of monitoring that will be employed to ensure that the agreed-upon work practices and engineering controls are being followed. Such proactive communication helps expand the trust of the employees by letting them know that their health and well-being are a priority.
Examples of good work practices to help minimize dust include wet-sawing or coring of concrete, using HEPA-filtered vacuum attachments for powered tools such as grinders, misting during sheetrock demolition, wet sanding of joint compound during installation of new sheetrock, and misting and sealing of waste containers before removing from the work area.
Engineering controls to minimize migration of construction dust to adjacent occupied areas should include:
- Separating the work area from adjacent areas with impermeable barriers, such as polyethylene sheeting.
- Sealing and shutting down (if possible) HVAC systems within the work area.
- Installing HEPA air filtration devices inside the work area that are exhausted outside of the space (preferably outdoors), thus establishing a negative pressure within the work area with respect to surrounding areas.
- Installing zippered doorways or airlocks at entrances/exits to the work area.
- Placing “sticky mats” at entrances/exits to the work area to help minimize tracking of dust to non-construction areas.
Monitoring during the project will typically include reviewing the effectiveness of work practices and engineering controls, performing direct-reading monitoring of airborne particulates, and sometimes collection of air samples for laboratory analysis.
The most effective form of air monitoring for this type of project uses a direct-reading aerosol monitor, such as a TSI DustTrakTM. This instrument provides a real-time concentration of airborne particulates so that any problems will be identified and can be addressed immediately. Some of these instruments can measure multiple particle sizes simultaneously, while others use a size-selective impactor to pre-condition the size range of the particles entering the instrument. Knowing the concentration at a given particle size is useful for comparing results with various exposure limits. However, the most useful approach is to compare measurements recorded during the work to baseline readings obtained before the start. Since the goal should be no impact to adjacent occupied areas, any prolonged elevation of readings above background levels should be cause for investigation.
Collecting air samples for laboratory analysis can be useful for comparison with specific occupational exposure limits. For example, one might want to sample for silica during concrete demolition. These results should always be supplemented with direct-reading results since there is typically at least a 2-day delay between collection of the sample and receipt of results from the laboratory.
In summary, a proactive approach to performing renovation adjacent to occupied areas should include planning, communication, and monitoring. These steps are a small investment to prevent potentially costly schedule delays and erosion of employee trust that can result from poorly planned or executed construction work.
Senior Environmental Specialist