The National Institute for Safety and Health at Work (INSHT) provides different tools to assess risks at workplaces. These tools support employers in their obligation to provide a safe and healthy workplace for their workers. This tool in particular calculates exposures to chemical substances. It helps users to assess the health risks arising from occupational exposure to chemical pollutants in the air based on the criteria proposed in the UNE-EN 689 Standard on Workplace Atmospheres. The assessment is based on a comparision of the time-weighted air concentration of a given pollutant, obtained from representative measurements, with the occupational exposure limits (daily exposure and the short-term exposure) set for the agent in question. The exposure determined in this way supports the employer in deciding on preventive measures in a timely manner.