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The re-entry interval (REI) (also known as restricted entry interval or re-entry time) is the minimum amount of time that must pass between the time a pesticide was applied to an area or crop and the time that people can go into that area without protective clothing and equipment.
NOTE: The term "pesticide" describes a very large and diverse group of chemicals or products. It is very important to always get specific information about the exact product you are using.
For more information, other OSH Answers documents in this series include:
Re-entry intervals are set to protect people (and animals, for example in a kennel) against poisoning by pesticides if they enter a treated area too soon after application without proper protective equipment.
There are many ways a person can come in contact with a pesticide. In general, exposure to pesticides may occur by:
When treated plants are touched during work activities such as weeding, thinning, or brushing against plants, some pesticide may be transferred to skin. Workers in a field can also cause residues on plants and on the soil surface to "fly up" as a dust. The dust then settles on the worker's skin and/or is inhaled. People in treated areas may also breathe vapours from a recent pesticide application.
Sometimes it's not as easy to avoid residues as you might think. Be aware of spraying activities on neighbouring properties. On windy days, spray drift can travel a surprising distance. If you smell a "solvent" smell and/or you notice a residue on the leaves of the plants you are handling, leave the area and ask the grower if he or she has sprayed recently.
The label on the pesticide container provides information on the re-entry intervals. A pesticide container label consists of several panels of information. If all the information does not fit on these container panels then additional information related to the re-entry time may be found in a separate booklet. There could also be stickers, tags, seals, leaflets, brochures and wrappers on, or attached to a container. For more information on labels, please see the OSH Answers Pesticide - Labels.
Provincial re-entry guidelines may also be available. For example, the WorkSafeBC Occupational Health and Safety Regulations state that the minimum restricted entry interval for:
See table 2 in the OSH Answers Pesticide - Labels document for examples.
For some pesticides, longer restricted intervals may be indicated on labels, and this interval must be followed. The Ontario Pesticides Education Program indicates that a 12 hour re-entry interval must be used when there is no information about the re-entry time.
Signs should also be posted that indicate spraying has occurred and what the re-entry interval is.
Workers who are trained and certified in handling pesticides may be allowed to enter the treated area to do short-term work before the re-entry interval is finished. Special precautions must be taken in these situations depending on how early the area is entered. However, nobody should enter the area in the first four hours after the application.
Different pesticides will have different re-entry intervals. In addition, each pesticide may have one or more different re-entry intervals. These intervals are established by considering the following:
If several pesticides are applied at the same time, the longest re-entry interval should be followed.
Recognizing symptoms of pesticide exposure helps you to know to leave the area immediately and to begin first aid treatment if required. For a list of health effects, please see the OSH Answers document Pesticides - Health Effects.
Some health effects can be vague and be confused with other illnesses such as flu, excess heat, or food poisoning. Be aware that symptoms may appear within a few minutes of exposure or may not be evident for hours. Use the "buddy system" and keep an eye on your co-workers as well. If anyone is acting or feeling unusual, or showing signs of health effects, see a doctor and call your local Poison Control Centre.
If you notice symptoms in yourself or a co-worker: