By Kim J. Gifford

No question about it. Whether it is new construction, demolition of an existing space or routine maintenance, construction creates dust and debris in the air that can be harmful to contractors and building occupants alike.

Contractors and planners need to take careful measures during construction to monitor and ensure proper indoor air quality for all those involved. In settings such as commercial offices, it may be as simple as scheduling construction when people are out of the building. Another solution is to evacuate the specific area under construction. Air quality measures, however, become much more critical in settings where occupants cannot be evacuated or are particularly sensitive to
irritants such as mold and dust.

Nate Carey, Trumbull-Nelson’s operations director, says that when working on an occupied building “isolating the construction area from other inhabited spaces in the building is the best option.” Such containment may be accomplished through temporary partitions installed before construction starts. In the simplest scenarios, explains Carey, “the solution may be as easy as making sure doors and windows are not used. Plastic sheeting is often pretty effective.”

Contaminants include mold that grows on walls (which can be disturbed by demolition) as well as dust from plaster, drywall and wood.

Hospital Settings

These solutions may be insufficient in hospitals, where patients cannot be moved or where immune systems can easily be compromised by the contaminants created by construction. Such contaminants include mold that grows on walls (which can be disturbed by demolition) as well as dust from plaster, drywall and wood. Other potential hazards to indoor air quality include renovation materials such as paints, adhesives and cleaning agents. Even construction equipment such as compressors and generators pose a threat to proper air quality.

“Industries like schools and other commercial buildings may also have an interest in maintaining indoor air quality during construction,” says Steven Cutter, director of Bio-Medical and Facilities Engineering at Dartmouth-Hitchcock Medical Center in Lebanon, N.H. “Certainly it has been an increased focus in health care.”

New standards published by the Centers for Disease Control and Prevention (CDC) perhaps best demonstrate this concern. These standards call for containment such as floor to ceiling barriers, HEPA filters, negative air pressure and the monitoring of air quality for even simple routine maintenance. In addition to the CDC, another regulatory body — the Joint Commission for the Accreditation of Healthcare Organizations (JCAHO) — also sets “environment of care standards” for the healthcare industry. JCAHO suggests that hospitals conduct an Infection Control Risk Assessment (ICRA) before construction to evaluate the risks associated with that specific project. “As a result, we no longer do construction out in the open,” says Cutter. Instead, hospitals like DHMC, isolate construction with floor to ceiling barriers that may consist of plastic sheeting or even hard cleanable surfaces, depending on the nature of the project.

“Pressure relationships between barriers are a common theme within health care. We have isolation rooms, so if somebody comes to the hospital with an infectious disease, we put them in a room to protect the people around them from whatever they have. If we have patients who are very susceptible to disease, we put them in a different environment,” says Cutter. “We just took the same rationale in construction and said, ‘We’re going to treat it as if there’s something in there that’s infectious and we don’t want people around it.”

Trumbull-Nelson relies on an air monitor that tests for four things: the percentage of oxygen, the carbon monoxide content, combustible gasses that might have accumulated and the amount of hydrogen sulfide present.

Cutter attributes the increased focus on maintaining air quality to a number of factors, including the overall industry attention to the incidence of infections acquired within healthcare clinics. In addition, the volume of construction within healthcare settings has increased in the last 15 to 20 years as medical centers expand. “There’s also a greater awareness of indoor air quality among the general population,” he says. “Mold issues, especially down south, have become prevalent recently.”

Now that the healthcare industry has addressed the risks and measures necessary for ensuring air quality during major construction, it is concentrating on more routine maintenance procedures as simple as replacing a ceiling tile. “All maintenance projects whether routine or major require constant air quality precautionary measures” says Cutter.

Worker Safety

Whether it be routine maintenance or more extensive construction, another population that faces the potential hazards of poor air quality is construction workers.

“We want to keep our employees safe,” says Trumbull-Nelson’s Carey, “and there are two things that concern us: particles in the air that we don’t want our people to breathe and hazardous atmospheres.”
Contractors typically deal with dust and debris by wearing dust masks and ventilating the construction area. Essentially, there are two ways to ventilate a space. The first is to create a negative atmosphere, which involves putting the intake on the ventilating equipment inside the space. The second way to ventilate a space is through positive pressure, which involves bringing clean air from the outside to the inside space.

Both of these methods have appropriate applications, although negative pressure scenarios are more common in construction. An exception to this, offers Carey, may be a situation in which a crew needs to enter a steam tunnel, such as those Trumbull-Nelson has worked in at Dartmouth College in Hanover, N.H. “It may be more practical depending on the layout and design of the tunnel to blow in fresh air, creating a positive pressure atmosphere,” he says.

Although the Occupational Safety & Health Administration (OSHA) standard 1910.146 does not specifically apply to the construction industry, contractors frequently rely on it as a guideline for approaching hazardous atmospheres within confined spaces. This standard suggests that contractors first test, then monitor the air within the confined space. Trumbull-Nelson relies on an air monitor that tests for four things: the percentage of oxygen, the carbon monoxide content, combustible gasses that might have accumulated and the amount of hydrogen sulfide present.

Workers do not have to enter an environment to test the air. Instead, they can send a tube down into the space and pump the air into the machine for testing. A few years ago, Carey used such a device when renovating The Nugget Theater on Hanover’s Main Street.

“The space was pretty much gutted, and we were running diesel engines,” he says. “We had to test the atmosphere inside the building to make sure our people were not overcome by carbon monoxide.” Some atmospheric hazards — flammable vapors, toxic gases or insufficient or overabundant oxygen — might require workers to use a self-contained breathing apparatus similar to that worn by a fireman when entering a burning building.

Air quality control measures can add to the cost of construction. But, as Cutter, explains, “They are just another feature of construction that we design for and live with.”

In commercial construction, such costs are often built into the contract under the heading “general conditions,” explains Carey. “Keeping employees, sub-contractors and occupants safe is our primary responsibility,” he says.