We all bemoan the horrible state of air quality in the United States, but did you know that interior air quality is often significantly more toxic than outdoor air? Check out this quote from the US Environmental Protection Agency:
"The average American spends approximately 90 percent of their time indoors." Yet, "...studies of human exposure to air pollutants by EPA indicate that indoor levels of pollutants may be 2 to 5 times – and occasionally more than 100 times – higher than outdoor pollutant levels. Indoor air pollutants have been ranked among the top five environmental risks to public health."