Since 1970, all homes in North America have been designed with highly airtight windows to conserve energy. The advantage of this design is that it prevents cool air from escaping during the summer, and heat from escaping in winter. The downside is that the airtight windows often lead to poor indoor air quality.

Gases and particles suspended in the air are the primary factors contributing to this poor indoor air quality. Common household items such as: Cooking fumes, paint, wooden furniture, household cleaning products, beauty products, house plants, humidifiers, and even the clothes and shoes of family members returning home are major sources of poor indoor air quality. Over time, this can lead to sensitivity and respiratory problems.

作者：Michael Chiu，MWS，CI
本文原載於《明報日報》。