The purpose of this report is to take stock of the current level of understanding and to evaluate the public health issues relating to glycol ethers and commonly used chemical substances present in the indoor air (second-hand tobacco smoke, radon, formaldehyde, volatile organic compounds, benzene, particles, etc.), by emphasizing certain concepts such as low dosages, a combination of dosages and multiple exposures, as well as the current limits of toxicology, epidemiology and, in general, environmental-health expertise. Modern man spends at least 80% of his time indoors (at home, at work, at the supermarket, in the car, in the metro, on the train, on the plane, in underground parking garages, etc.), where the air is more polluted than outside. This necessarily has an adverse effect on health, in particular that of the more sensitive populations (pregnant women, children, asthmatics, persons with allergies, etc.).