Hantavirus disease is a rare but potentially fatal infection spread by deer mice and possibly by other rodents.

The Occupational Health Clinics for Ontario Workers Inc. have prepared this document to provide guidance using only temperature and humidity data. For brief summer heat spells this plan may be appropriate, see the plan for extreme conditions and be sure that your conditions are appropriate before employing the response plan suggested by this document.

West Nile Virus is primarily a bird virus that is spread from bird to bird and from birds to humans and other animal mainly by Culex species of mosquitoes.

This document addresses heat and humidity combinations which are more extreme and can affect health more severely. Some of the monitoring equipment identified in the document can be borrowed from the Occupational Health and Safety Division to perform initial testing. For work processes that create excessive heat year round, advice on where to purchase applicable equipment can be provided by the Division.