A consultation on plans to introduce tougher pollution limits on vehicles in London has begun.
The Ultra Low Emission Zone would be introduced in 2020 and is aimed at halving nitrogen oxide and particulate matter, Transport for London said.
A daily charge of £12.50 for cars and £100 for HGVs, coaches and buses would have to be paid if they were not compliant with the new standards.
Critics have said the proposal is "too little, being introduced too slowly".
Cars no longer exempt
However, The Federation of Small Businesses said the Congestion Charge was already a "mere tax on business operations".
It said it was concerned that some drivers would have to pay three separate charges - for the Congestion Charge Zone, Low-Emission Zone and Ultra Low Emission Zone.
Transport for London has said while this is possible it is "likely to happen infrequently".
London is currently in breach of legal limits for nitrogen dioxide which impacts public health, says documentation supporting the consultation.
The proposed charge would take effect from 7 September 2020, apply 24 hours a day, seven days a week, and operate in addition to and in the same area as the Congestion Charge Zone.
The current Low Emissions Zone does not apply to cars or motorcycles, but the new one would.
Owners of petrol cars older than 14 years in 2020 will have to pay £12.50 to enter the zone since only cars manufactured from 2006 will meet the particulate emissions standard demanded by the new zone.
Owners of diesel cars older than five years in 2020 will also have to pay £12.50 since 2015 is when manufacturers will meet the new standard.
Buses and lorries over six years old in 2020 will have to pay a daily charge of £100.
'Too little, too late'
Agricultural, military and historic vehicles would be exempt, along with non-road going vehicles allowed to drive on the highway, such as excavators.
Transport for London is budgeting about £30m in capital costs to set up the new zone, including policy development, consultation and marketing costs.
The consultation will run until 9 January 2015.
London Assembly Member Jenny Jones of the Green Party, said the proposal was "too little, too limited and too late" - a criticism also made by Liberal Democrat spokesman Stephen Knight.
Baroness Jones suggested boroughs outside the zone should be given an opportunity to opt-in at the earliest possible opportunity.