At all LEZ entry points there are signs like these.

Inside the Zone

Once you're inside the LEZ, on main roads there are signs to remind you that you're in the zone and that the scheme is enforced by cameras: 

Advance warning signs

On major approaches to the M25, advance warning signs like these indicate the position of the LEZ boundary, allowing you to choose to divert onto the M25: 

Additional advance signs

Closer to the boundary itself, some approaches have additional advance signs to indicate a route you may take to avoid entering the zone:

How the LEZ works

There are no barriers or toll booths within the LEZ. Instead, cameras will read your number plate as you drive within the LEZ and check it against our database of registered vehicles.

This database is compiled using information from the DVLA and the Driver and Vehicle Standards Agency (DVSA), generic vehicle weight data typical of the make and model, and drivers and operators who have registered with us.

This tells us automatically whether your vehicle meets the LEZ emissions standards, is exempt, is registered for a discount, or if you've already paid the daily charge.