VOC stands for ‘Volatile Organic Compounds’. I could give you the fancy scientific definition but for our purposes regarding your floors let’s keep it simple. It is the off gassing that occurs from chemicals that are applied as protective coatings to floors. The smell to put it very simply. It is measured in grams per liter or g/l . You can find out more about VOC’s and other air quality issues here: https://www.epa.gov/indoor-air-quality-iaq