The introduction of a clean air zone in Bristol will cost one local charity around £6,000 a year.
Suicide Prevention Bristol regularly drives three vehicles into the city centre to help those in need.
The two cars they drive for patrols on Friday and Saturday are not compliant with the zone.
Imogen Fox, who works for the charity, said: "It's going to make a massive difference for us, we are completely reliant on donations.
"We drive two response vehicles to go and help prevent suicide in Bristol and it's going to cost us an extra £6,000 a year."
The charity could at times have to pay the charge twice because the cut-off time for the zone is midnight.
Imogen explained: "Friday and Saturday night we have two vehicles out every night from 9 in the evening until 3 in the morning and because the cut-off will be midnight we'll have to pay twice, both Fridays and Saturdays.
"It just seems such a dreadful waste of money to then be giving it back to the council when we're absolutely desperate for donations all of the time."
There are exemptions for some driving into the zone with non-compliant vehicles but charities do not qualify for an exemption by default.
Under the scheme, which comes into effect on Monday (28 November), older cars will be charged £9 a day, as will taxis and light good vehicles. HGVs, buses and coaches will have to pay £100 to travel through the zone.
The aim of the clean air zone is to reduce nitrogen dioxide levels, a substance which is damaging to our health. Levels regularly reach illegal levels.
Dr James Matthews from the University of Bristol said: "The measurements over a year are frequently over that limit in Bristol particularly in the centre.
"Any reduction in traffic will be a positive for the health of the city but we do need to keep an eye on other pollutants as well as NO2 to make sure that they are not increasing and we need to look into whether the displaced traffic is creating pollution elsewhere.
"But I am hopeful there will be a good effect."
Many in the city centre hope the new clean air zone will be positive for their health. Joanna Booth has had Covid several times, and says she is often affected by the high levels of pollution in Bristol.
She told ITV News West Country: "I have real issues, about a year ago I developed long Covid so even just breathing hurts most of the time.
"Our windows have those black bits on them so we have to constantly clean those so the pollution in BS1 is incredible and it's getting worse so I am very glad and I am hopeful for clean air just because of my health. I find it really tough."
For those who have been campaigning for better air quality, the zone does not go far enough.
Dr Jonathan Monk-Cunliffe said: "There are some studies that think that maybe it might save 20 lives a year but really we need to go further, so we need the government to give Bristol council the investment so it can bring us clean air, green jobs, better transport infrastructure that can improve everyone's health."