Renovations can often make a building more energy-efficient; however, they can also exacerbate indoor health risks.

Lead, asbestos and PCBs
In older buildings, demolition and sanding can release dust contaminated with toxins like lead, asbestos and PCBs (polychlorinated biphenyls).

Until the 1960s, lead was used extensively in plumbing and paint. Lead is a potent neurotoxin, so disturbing it can have lifelong impacts on the intelligence of children.

Asbestos was used in insulation between the 1930s and early 1980s, and asbestos-containing vermiculite was used until 1990. Asbestos was also used in ceiling tiles, vinyl flooring and shingles, among other products. Even short-term exposure to friable asbestos fibres can cause lifelong lung damage.

PCBs were used as ingredients in sealing and caulking products to make them more flexible. These chemicals may be found in caulking around windows and door frames in buildings constructed or renovated between 1950 and 1978. When exposed to heat, PCBs can breakdown into extremely toxic dioxins and furans.

Other threats to health
Making a building airtight to conserve energy can decrease air exchange. This may mean buildings with indoor sources of pollution such as radon and carbon monoxide keep more of it inside.

As well, many newer building materials, including particleboard, paint, glue and carpet, off-gas volatile organic compounds (VOCs), which contaminate indoor air and accumulate at higher concentrations in poorly ventilated buildings.

Dianne Saxe and Jackie Campbell are environmental law specialists.