Toxic vapors force Google to shut two buildings close to it's Mountain View HQ Google has been forced to evacuate staff from two buildings close to it's Mountain View HQ in California due to toxic vapors seeping up from the ground below. The dangerous air pollution is being caused by trichloroethylene, a powerful solvent also known as TCE, which has leaked into the soil and polluted the groundwater. The pollution is the legacy of chip makers including Fairchild, Intel and Raytheon who dumped thousands of gallons of the toxic solvent into the ground when they worked in the buildings in the early days of Silicon Valley. Google has been forced to evacuate staff from two buildings near it's Mountain View HQ due to dangerously high level of air pollution The impacted buildings are QD6 and QD7 on North Whisman Road, Mountain View According to the Environmental Protection Agency, since cleanup began in the early 1980s more than 74 million gallons of groundwater have been treated and 2,000 pounds of volatile organic compounds removed. When Google moved into the impacted buildings, QD6 and QD7 on North Whisman Road, they installed state of the art filters, and conducted rigorous air quality testing. Recent tests however have recorded excessive levels of TCE in the air in some areas of the buildings. A normal screening level for commercial buildings is five micrograms per cubic meter. Most of Google's air sample stations in the two buildings detected TCE levels below that, but about a dozen stations reported readings from 5-30 micrograms per cubic meter. One station even reported 120 micrograms per cubic meter. Google employees have been exposed to the problem for 'months', but it 'takes decades of exposure to cause problems', the EPA told CBS. The pollution is the legacy of chip makers including Raytheon and Intel who dumped thousands of gallons of the toxic solvent into the ground when they worked in the buildings in the late '70s Google has released a statement saying that the health and safety of employees is it's number one priority Google has released a statement, saying 'The health and safety of our employees is Google's number one priority, and we take several proactive measures to ensure the healthiest indoor air environments possible.' As well the Google buildings, residential homes in the area have also been fitted with state-of-the-art pumps to blow the toxic vapors away. Treatment also continues under the ground with vapor barriers in place, so-called slurry walls going down 40 feet into the earth, well sucking up water to be treated, and systems operating to extract toxins from the air and water. A study last year found a spike in TCE-related cancers in the area around the Google buildings. Video: Toxic vapors seeping up from underneath Google buildings