Readers question: MARK from Durham wants to introduce some house plants to his workplace because he has heard that they can help clean the air. He would like to know if this is true and, if so, what other health benefits could he look forward to?

PLANTS have indeed been proven to remove airborne harmful contaminants. There is a wealth of scientific study into the beneficial effects of live plants in the interior environment, including a large NASA programme.

The majority of the population spend time indoors at home or work. Air conditioning, improved insulation and energy-saving systems all reduce the air exchange in buildings, so we breathe the same air again and again.

Add to that the fact that the modern internal environment is virtually hermetically sealed and that synthetic furnishings, computers, electrical equipment, and everyday cleaning material, can produce harmful substances, and we are left with something that is recognised as “sick building syndrome”. Polluted indoor air is a major cause of headaches, nausea, sore and itchy eyes, loss of concentration and a whole array of other symptoms. Interior plants can help remove these pollutants.

Humidity is another important and often underestimated factor in human health. When humidity levels are too low, we are more likely to develop viral infections; when humidity is too high, vulnerability to other disease increases.

Plants tend to control humidity to within the optimum range for human health.

Plants absorb carbon dioxide and emit oxygen. This increased oxygen level refreshes the air – and you – leading to increased concentration and between ten and 15 per cent increased productivity.

According to a University of Agriculture in Norway study, indoor plants can reduce fatigue, coughs, sore throats and other cold-related illnesses by more than 30 per cent, partially by increasing humidity levels and decreasing dust.

Even major corporations and work environments are beginning to catch on that adding plants indoors does wonders for employee health and morale. According to one study, a manufacturing company integrated plants into its office so that no employee would be more than 45 feet from greenery. Company administrators said they noticed enhanced creativity and increased productivity in employees.

So yes, Mark, I suggest that you go ahead fill your office shelves and top your filing cabinets with a variety of houseplants.

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As long as the ground is not to waterlogged or frozen, you can plant herbaceous perennials, shrubs, deciduous trees, roses and fruit trees.

Finish planting pansies, wallflowers, forget-me-nots and primulas. They need to be in by early November.

Perennials more than a few years old or causing congestion within the border can be lifted and divided. When dividing, replant the outer divisions and throw away the middle part.

■ Brigid presents the BBC Tees Gardening show on Sundays from 1pm to 2pm.

Questions can be answered on the day by emailing brigidpress@bbc.co.uk anytime during the week, or texting 07786-200995 and phoning 01642-225511 during the show.