Did the EPA get involved in making recommendations about carpet cleaning frequencies? Actually yes, they did more than that. In 1991 and 1994, representatives from the Research Triangle Institute led by Dr. Michael Berry did two ground breaking studies on behalf of the United States Environmental Protection Agency on the interaction between professional truck mounted carpet cleaning and the reduction of potentially harmful contaminants in the indoor environment. The knowledge and information they gleaned from these studies was the forerunner to Dr. Berry and other public and private health officials being involved in the on-going updates to the IICRC Carpet Cleaning Standard S100. These frequency recommendations are one of many important outgrowths of those original groundbreaking studies. The evidence is overwhelming and growing. Cleaning your carpet with professional hot water extraction on a scheduled periodic basis is one of the best contributors there are to making an indorr environment healthier and safer.