Biological/chemical threats by post

Members of the public and businesses should always remain alert to the danger of terrorism; information on the current threat level to the UK can be found on the MI5 website. You should be aware of the practical steps to take immediately if you receive a suspect package or come into contact with a biological (eg anthrax) or chemical substance.

Terrorist or criminal incidents of this nature are extremely rare. However, if there is a concern that a suspect biological/chemical package has been received, sensible steps can be taken to minimise the risk of exposure and the possibility of harm. The overall message is to remain calm.

General mail handling - what to look for

  • Look out for suspicious envelopes or packages (see below for some things that should trigger suspicion).
  • Open all mail with a letter opener or other method that is least likely to disturb contents.
  • Open packages/envelopes with a minimum amount of movement.
  • Do not blow into envelopes.
  • Do not shake or pour out contents.
  • Keep hands away from nose and mouth while opening mail.
  • Wash hands after handling mail.

If you are in any doubt about a package, do not touch it, move it or open it and call the police on 999.

Some items that can trigger suspicion

  • Discolouration, crystals or surface, strange odours or oily stains
  • Envelope with powder or powder-like residue
  • Excessive tape or string
  • Unusual size or weight given size
  • Lopsided or oddly-shaped envelope
  • Postmark that does not match return address
  • Restrictive endorsements such as "Personal" or "Confidential"
  • Excessive postage
  • Handwritten, block-printed or poorly-typed addresses
  • Incorrect titles
  • Title but no name
  • Misspellings of common words
  • No return address
  • Addressed to individual no longer with organisation

General mail handling - what to do

If you believe you have received a contaminated package

  • do not touch the package further or move it to another location
  • shut windows and doors in the room and leave the room, but keep yourself separate from others and available for medical examination
  • switch off any room air conditioning system
  • notify building manager

Your building manager should

  • notify police immediately using the 999 system
  • switch off the building air conditioning system
  • close all fire doors in the building
  • close all windows in the rest of the building
  • If there has been a suspected biological contamination, ensure that personnel outside the room are evacuated as soon as possible and ensure individuals in the contaminated room are evacuated to an adjacent unoccupied room away from the hazard.
  • If there has been a suspected chemical incident ensure personnel leave the room as quickly as possible. Possible signs that people have been exposed will be streaming eyes, coughs and irritated skin. Seek immediate medical advice.

If you find a suspect package outside a building

  • do not touch it or move it
  • inform the building manager clearly stating why you believe a biological/chemical material is involved

The building manager should

  • notify police immediately using the 999 system
  • switch off the building air conditioning system
  • close all fire doors in the building
  • close all windows in the building
  • move people away from the hazard and await instructions from the emergency services

If anyone believes they have been exposed to biological/chemical material

  • remain calm
  • do not touch eyes, nose or any other part of the body
  • wash your hands in ordinary soap where facilities are provided, but staff movement outside contained locations should be avoided as much as possible

notify police immediately using the 999 system

  • keep all persons exposed to the material separate from others and available for medical attention
  • other people should assemble at a safe distance from the incident and continue to be guided by the police and the other emergency services

What to do if you are an employer or a manager

Consider what you should be doing now, and what contingency plans you need for handling mail and suspect packages and your response plans in the event of your receiving a suspect letter or package. Ensure that plans are regularly rehearsed.

Health and safety at work legislation, including the Biological Agents Directive, clearly states that when selecting preventative measures to control risks to workers and others, employers must select from a hierarchy of measures. These are set out below.

The first step is to review your current risk assessment and your procedures for handling mail in your organisation or business. In doing so consider the possibility, however small, of your business receiving suspect packages.

  • As part of any contingency planning you will need to have measures in place to quickly trace a suspect letter or parcel back through the mail handling system. This would enable you to identify anyone in the workplace who may have been exposed to a risk to their health and safety so they can be treated quickly.
  • When performing risk assessments in the workplace and selecting adequate control measures involve employees in the risk assessment process and provide them with relevant information on what the risks are and what steps need to be taken to ensure they are adequately controlled.
  • The hierarchy of control measures you need to consider includes:
    • prevention of exposure (eg restricting the numbers of employees handling the mail)
    • engineering controls (eg filters on machinery and air extracting systems)
    • good housekeeping measures (eg appropriate filters on vacuum cleaners and other cleaning devices) and
    • the use of personal protective equipment (PPE) (eg masks or gloves).
  • PPE should only be considered if the risk assessment indicates that it is appropriate after all other controls have been addressed. When considering PPE to control risks it is important that you select the equipment that is suitable for the task being performed as well as for the risk being considered. PPE is only effective if it is used properly, so employees need proper training on good hygiene and the use, storage and disposal of the equipment. Further information on hand/skin protection is available in Annex 1.

This advice will be updated as new information becomes available. Employers may take this guidance and produce specific procedures that are suitable for their workplaces.

Annex 1: Guidance on masks and hand/skin protection to reduce the risks from exposure to anthrax

Where the risk assessment you have conducted as part of your contingency planning indicates that PPE is appropriate and you are considering masks and hand/skin protection as part of the measures you adopt to adequately control the risks of exposure from anthrax, you should note:


An appropriate mask can help to reduce the risk of inhaling anthrax spores. A range of disposable and reusable masks, all fitted with an appropriate filter (P3), are available. The right mask must be selected on the basis of:

  • suitability for the task being carried out;
  • level of protection offered;
  • work factors eg work load, communication requirements etc; and
  • personal factors eg face shape, physical condition.

The mask must be worn continuously to provide protection. There can be no eating, blowing of the nose or scratching of the face. It is important that people are trained to use the selected mask correctly if it is to be effective.

Hand/Skin protection

The most important factor in protection of the hands and skin is the covering of cuts and grazes with plasters and availability of hand-washing facilities. Although anthrax does not pass through intact skin, even minor cracks and abrasions in the skin do provide a route for infection.

Gloves provide an extra barrier but must be correctly chosen and used diligently. Particularly important are work factors (eg work could cause cuts and grazes to skin) and training in the use of the protection particularly putting on and taking off gloves. It is also important to consider any additional risks (eg from latex sensitivity).

Further information on PPE

The Personal Protective Equipment at Work Regulations 1992: Guidance on the Regulations - provides practical advice on how to comply with health and safety law related to PPE and on the selection of PPE. In addition further booklets on gloves and respiratory protective equipment will also provide useful further information. See annex 2 on additional useful information.

When considering what PPE to select, manufacturers/suppliers should be consulted for advice on suitable protection for your situation. The Personal Safety Manufacturers Association can provide details of those Companies who will provide advice and suitable equipment and can be contacted via the British Safety Industry Federation Information Desk (e-mail [email protected] or telephone 01745 585600).

Annex 2: Additional useful information

The following publications will provide further useful information:

Other related websites:

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Updated 2022-05-20