According to the World Health Organization (WHO) "Air pollution from both outdoor and indoor sources represents the single largest environmental risk to health globally", and causes 7 million deaths a year, worldwide.
On average, people spend 90% of their lives indoors (and some, such as the elderly, even more). This has caused the level of indoor air pollutants
to increase 2-5 times higher than outdoor levels.
Indoor air pollution can lead to serious short and long-term health problems. There has also been growing evidence that air pollution impacts
mental health and may be a factor in conditions such depression and bipolar disorder. It may also have a detrimental effect on children's learning
ability, patient recovery and workforce productivity