Some of these particles, if they are present only in small quantities, do no apparent harm. Other types of dusts may damage the surrounding alveolar walls. The damage may be permanent and may cause scars to form, which eventually interfere with the lung's ability to pass oxygen into the blood stream. Gases and Vapours Workplace chemicals can enter the air in a number of different ways. Simple evaporation is probably the most common way.
Evaporation produces vapours.
Vapours are formed from substances that exist as solids or liquids under normal temperature and pressure conditions. Substances that do not exist as solids or liquids at normal temperatures and pressures are called gases. Gases as well as vapours can contaminate the workplace air. In some instances, an industrial process might produce tiny liquid droplets that are able to float in the air. These droplets are called mists.