Health and Safety
Executive / Commission
Publications
This guidance is issued by the Health and Safety Executive. Following the guidance is not compulsory and you are free to take other action. But if you do follow the guidance you will normally be doing enough to comply with the law. Health and safety inspectors seek to secure compliance with the law and may refer to this guidance as illustrating good practice.
Vessels in port are often seen with their radar scanner rotating. Does this mean that port workers are being exposed to harmful radiation? This information sheet, which is one of a series issued by the Health and Safety Executive's Docks National Interest Group, explains the hazard and level of risk associated with radar on civilian vessels in commercial ports.
A ship's radar equipment has three major components; the generator itself, the monitoring screen, usually on the ship's bridge, and the antenna or scanner, usually mounted high up on the superstructure. Radiation from the scanner scans out almost horizontally in a narrow beam as the scanner rotates and when the ship is in port will encounter dock buildings and equipment such as cranes, gantries etc. The beam will not normally spread down to pick up the ship superstructure or deck.
Although a ship does not normally need its radar equipment operating while in port, many rapid turnaround roll-on roll-off vessels and other short stay or on-call vessels such as tugs may well keep their radar equipment operating at all times. Additionally longer stay vessels may need to switch radar equipment on some time before they leave port, to enable the unit to stabilise: they may also need to keep the scanner rotating at all times to prolong bearing life and ensure smoothness.
The scanner may be rotating but the set itself may not be operating since it is common practice for shoft stay vessels to put radars onto 'standby' while in port. No radar emissions occur on 'standby'.
It is sometimes possible to operate a radar set with the scanner stationary but this will usually require some action to override the system for any significant power to be used.
Radar equipment may also be operated in port for routine maintenance, servicing or repair work.
Marine radar systems operate in the high radio frequency (RF) and microwave range. Unlike X-rays and nuclear radiation the emissions are non-ionising radiation and do not penetrate the human body but can cause heating of the surface, particularly of the skin and eyes (cornea).
The output power from marine radar equipment can vary between similar radar sets and with a number of other factors, including:
The power level people might be exposed to near a radar scanner will also depend on a number of additional factors, including:
The National Radiological Protection Board (NRPB) has published guidance on exposure to non-ionising radiation (Documents of the NRPB - Volume 4 1993 - Board Statement on Restrictions on Human Exposure to Static and Time Varying Electromagnetic Fields and Radiation). This document recommends investigation levels which set the power density above which people should not normally be exposed. In the relevant frequency range this is 100 watts per square metre (Wm-2)): this is the same as 10 milliwatts per square centimetre (mWcm-2) or 10 000 micro watts per square centimetre (μWcm-2).
A typical container ship (with a capacity of about 3000 TEU) might have radar sets of 50 kW (3 cm wavelength) and 60 kW (10 cm wavelength), and a smaller vessel such as a tug might be equipped with a 10 kW set. Measurements taken, in a port, 10 meters from the stationary scanner of a container ship fitted with both a 50 kW set and a 60 kW set, and tests carried out by a manufacturer of radar equipment 10 metres from a 10 kW set with a stationary scanner, have all shown power densities significantly less than 100 μWcm-2.
The examples show that the expected power densities from exposure to ships' radar at a distance of 10 metres are less than 1/100th of the investigation levels even when the scanner is stationary. Marine radars normally operate with a pulsed signal and a rotating scanner, so people are not continuously exposed to radiation even if they are in a fixed position such as a crane cab or an office adjacent to shipping.
No link between ill health and exposure to microwaves at levels below the NRPB recommendations has been established in the UK among microwave communications and radar engineers in the armed services, electronics, broadcasting or communications industries. The NRPB Advisory Group on Non-lonising Radiation has concluded that there is no clear evidence of a carcinogenic hazard from the normal levels of radio frequency or microwave radiation to which people are exposed.
It is unlikely that any port worker will be exposed to significant risks from the marine radar emissions of a commercial vessel, during normal port activities.
If radar equipment is to be worked on under power in port, sensible precautions would include ensuring that:
Any work carried out on such equipment should be carried out by competent persons, operating a safe system of work, so that they put neither themselves nor others at risk.
HSE priced and free publications are available by mail order from HSE Books, PO Box 1999, Sudbury, Suffolk CO10 6FS. Tel: 01787 881165 Fax: 01787 313995.
HSE priced publications are also available from good booksellers. For other enquiries ring HSE's InfoLine Tel: 0845 345 0055 , or write to HSE Infoline, Caerphilly Business Park, Caerphilly, CF83 3GG.
This leaflet contains notes on good practice which are not compulsory but which you may find helpful in considering what you need to do.
This publication may be freely reproduced, except for advertising, endorsement or sale purposes. Please acknowledge the source as HSE. This information is current at 11/94.
Printed and published by HSE 11/94 NIS/07/05 C40
Added to the web site 5/5/98