Dear Tom,
It is good to have plants in our houses, but how many plants do we need in order to keep the air in our houses clean?
Steph Roblevitch, Berwyn

Dear Steph,
Houses are often tightly sealed in order to lower heating and air conditioning costs, but the downside is that indoor air can become polluted to the extent that occupants suffer distress from “sick building syndrome.” Studies to determine the air-cleansing qualities of plants have been conducted and it is known that plants do indeed remove pollutants from indoor air. It has been found that one plant per approximately 100 square feet of floor space can help combat the effects of sick building syndrome. In addition, plants can help to raise indoor relative humidity in the winter.