The world’s first Ultra-Low Emission Zone (ULEZ) will open in central London from April 8, 2019, the capital’s Mayor Sadiq Khan has confirmed.
The ULEZ will replace the recently introduced T-Charge and operate in the same area, alongside the London Congestion Charge. But – unlike the T-Charge and Congestion Charge, which are only in place on weekdays – the ULEZ will operate 24-hours a days, seven days a week, 365 days a year.
Diesel vehicles that do not meet Euro6/VI emission standards and petrol vehicles that do not meet the Euro4 standard will have pay to enter the area inside the ULEZ. 
There will be two ULEZ charge levels: £12.50 a day for cars, vans and motorbikes and £100 a day for lorries, buses and coaches. The charges will be in addition to the Congestion Charge, so the more polluting cars and vans would pay £24 per day and lorries would pay £111.50 during Congestion Charge hours (discounted for Congestion Charge Fleet Auto Pay registered vehicles). 
However, by the time the ULEZ comes into effect, it is anticipated that very few businesses will be operating pre-Euro6 diesel or pre-Euro4 petrol cars or vans. Although, it is forecast that there will be many lorries in operation that do not meet entry emission standards.
The fine for non-payment of the charge if a vehicle does not meet the ULEZ standard is £130 reduced to £65 if paid within 14 days for cars, vans and motorbikes and £1,000 reduced to £500 if paid within 14 days for lorries, buses and coaches. 
The area covered by the ULEZ is planned to be extended up to the North/South Circular roads in 2021 subject to a consultation later this year. Additionally, the Mayor is developing proposals for a London-wide Euro6/VI standard for buses, coaches and lorries for introduction in 2020.