Car users are being given stress-testing devices in a bid to reduce road accidents.

East Sussex County Council is issuing biodots, small stress-sensitive patches worn on the wrist, as part of a road safety campaign launched by lead cabinet member Councillor Anthony Reid.

Road safety officer Keith Sinden said: "The biodots are suitable for both passengers and drivers to wear but we are targeting passengers in this initiative. The dots change colour depending on whether a person is relaxed or stressed. Research has shown drivers who are tense, frustrated or tired will have more accidents.

"We also know this stress is transferred to other people in the vehicle and accidents can be prevented if a passenger speaks up when they recognise the danger signs.

The biodots are provided on a leaflet offering advice on how to raise issues of dangerous driving in a positive rather than a critical way."

The biodots are being distributed across the South- East on 62,000 of the stress advice leaflets.

The science is based on changes in skin temperature experienced under stress. Adrenalin is produced and triggers blood to be pumped to the muscles, ready for a "flight or fight" reaction, when stress levels rise.

The movement of warm blood away from the skin's surface lowers external body temperature, a result which can be shown on the biodots.

When wearers are calm, the dots will show a blue or green colour but when they become stressed the patch turns brown or black.

Mr Sinden said: "The principle behind the biodots has been used before for medical purposes but this is the first time it has been made available for a consumer project of this type and scale.

"The idea came from work the East Sussex road safety team was undertaking with drivers who had had accidents and had come to us for training courses to improve their road skills.

"We heard about patterns of bad driving under stress which were exacerbated because passengers did not feel able to use their influence before a situation got out of control."

The team spoke to passengers and found 62 per cent of people often felt unsafe, with common concerns being driving too close, too fast or with a bad attitude.

The research showed 89 per cent of passengers felt comfortable addressing a spouse's or partner's unsafe driving but less people would comment to a colleague or relative (57 per cent), friend (53 per cent), taxi driver (27 per cent) or bus driver (13 per cent).

Mr Sinden said: "It can be difficult for passengers to talk about a driver's behaviour and the biodot technology provides a simple and visual way of demonstrating the problem.

"The campaign is aimed at enabling people to have power from the passenger seat.

It is not about back-seat driving but about making sure all drivers are reminded to use common sense on the road and do not drive when they are adversely affected by stress.

"Everybody has different acceptable levels of risk taking and, for a good travelling experience, it is important to match these levels for all in the car. If a driver is operating outside acceptable safety levels, he or she needs to be told what the problem is.

"This is particularly important in a commercial setting where we have found people are less likely to say something. If a bus or taxi driver does not respond to a request from a passenger, it is a matter which should be taken to their boss."

Information on calming techniques is detailed on the leaflet, which has been produced in conjunction with the department of biological sciences at Manchester University. The leaflet suggests tact and diplomacy but urges passengers to speak up if the driver is travelling too fast, following too close or overtaking in a risky way.

www.eastsussexcc.gov.uk