British holidaymakers in France have been urged to ensure they have a valid emissions sticker for their car or face a fine of more than £100.
A number of areas including Paris recently introduced new air pollution rules requiring vehicles to display an emissions sticker and banning the most polluting cars from entering clean air zones at certain times.
But only around a third of British motorists are aware of the new restrictions, according to research from the RAC.
Failure to follow the rules will result in a "near certain" fine of up to £125, it warned - a sum big enough to spoil holiday memories.
- What are the new 'Clean air' rules?
The French clean air stickers - called Crit'Air vignettes in French - have been introduced by a number of major towns and cities under a drive to reduce air pollution.
Areas which have signed up to the scheme require all vehicles to display a sticker showing how heavily polluting they are.
There are six categories in all, ranging in colour from dark green for the cleanest cars to dark grey for those with the dirtiest emissions.
Details of the rules vary from area to area, but some towns are banning the most heavily polluting vehicles from entering some areas at certain times.
Simply failing to display a valid sticker will leave drivers at risk of an automatic fine of between €68 (£63) and €135 (£125), as will driving in zones where they are banned for being too polluting.
- Which areas have introduced the rules?
A number of cities have signed up, including tourist hotspot Paris and a number of other towns and cities near the northern border closest to the UK.
The capital is using the sticker scheme on all weekdays, though the restrictions do not apply at nights or weekends.
The other three areas affected are Lyon, Grenoble and Lille, though they have all said they will only apply restrictions on vehicles on am "emergency" basis when pollution peaks.
More areas are expected to sign up to the Clean Air scheme shortly, with Bordeaux and Strasbourg expected to join by the end of 2017.
- What vehicles are affected?
Every motorised road vehicle must have a valid sticker, from motorbikes to family cars, goods vans and coaches.
The rules apply to both French and foreign cars, and disabled drivers are also expected to comply.
- What do motorists need to do?
Motorists should apply for a sticker from the official Crit’Air website, at a cost of €4.80 each.
Drivers will also need to know their vehicle's European Emissions Standard. The RAC has produced a table that helps identify the correct level, or otherwise contact your vehicle's manufacturer.
It should then be fixed onto the windscreen - or on a clearly-visible surface for vehicles that do not have windscreens.
The sticker is valid for the lifetime of the vehicle and does not have to be updated on future trips as long as it remains on display.
Some of the oldest and highest-polluting vehicles will not be eligible for any of the six stickers, and these cars are banned from driving in Paris between 8am and 8pm on weekdays.
Visitors should also check local rules in areas applying the scheme to ensure they don't drive in areas when they are barred under its restrictions.