How to grow clean air

Indoors is where we spend most of our time -- nearly 90 per cent of it, in fact. In our homes, offices and recreational facilities we're vulnerable to biological pollutants (like mould, dust and dander) and chemical pollutants from the materials we use to build, heat, furnish and clean our environments. Dangerous chemicals like formaldehyde, alcohols, benzene and other volatile organic compounds (VOCS) can be released into the air from items like carpeting, synthetic materials, resins and common cleaning products like air fresheners. New products can continue to "off-gas" for years after their installation.

We're often told to "plant a tree" to help the environment. What if we could use that principle indoors as well? Scientists have long known that certain plants can actually improve indoor air quality by removing toxins from the air. But how can you find plants to suit your needs?

NASA researcher Dr. B.C. Wolverton studied the effects of houseplants on indoor air quality and used his findings to create How to Grow Fresh Air: 50 Houseplants that Purify Your Home or Office. The book explains some of the issues and science behind the problem, but also serves as a grower's guide for selecting and carrying for plants that clean the air. The science isn't new, but it's worth a second look considering today's environmental concerns.

Wolverton tested dozens of plants and assigned them an overall score. How well plants removed chemicals was just one of the criteria. He also considered the transpiration rate (how quickly the plant releases moisture into the air), resistance to pests and bugs and how easy it is to care for the plant. The trick is to find the best ones for your needs -- plants that will do the job, but won't require a lot of attention.