NIOSH (National Institute for Occupational Safety and Health) has an informative page on their site dedicated to the different kinds of cold stress workers can be exposed to in winter months, as well as symptoms and first aid remedies to treat those symptoms.
Below is a quick fact sheet from NIOSH on this topic and how you can protect yourself. This fact sheet can also be downloaded and printed to display at your company, or distribute to workers who are exposed to the elements this winter season.