You have listened to a radio discussion programme about which measures could be taken, by local authorities to reduce traffic and pollution in big cities.

We more commonly see program spelt in this way.
In this particular context, I have heard ‘measure’ pluralised most often.

Some opinions that have been/that were expressed in the discussion:

If the discussion was in the past, adding either one of these creates cohesiveness and flair.

“Cars are the main factor contributing factor to pollution and should not be allowed toin the city centre.”

I have heard this word order before, but either one suffices.
Take care with your prepositions !

“The costs involved/The cost of imposing a congestion charge iswould be much higher than the benefits.”

I am assuming the congestion charge hasn’t been implemented, therefore, we would talk of it hypothetically; “if x happened, y would happen”.

Write an essay discussing two odf the solutions in your notes.

(What changes could make it sound more natural?)

This sentence is quite brief, so I added context for cohesiveness.

)

Recently I heard a radio debate about the need tof reducinge contamination in big cities, especially from vehicles in downtown areas.

Downtown is never used as a plural.

Basically, two solutions were expodiscussed in this discussion: offering a public transport discount for all ages or charging drivers in the city centre.

Exposed is not correct here.

AsIn regards to/Regarding the last measure, I completely agree with some the participants who remarksed that it would be an expensive one, although not economically.

I mean, this will be ant would be expensive within the opinions of the city’s citizens, as it would most likely be considered a highly unpopular measure (synonyms?.

Very sophisticated.

), which willThus, makeing it non-effective in terms of durability, since political parties would not support the negative effects of it within an election process.

In the debate I also heard that cars represent the first source of pollutants in big cities, so it was proposed that we should consider banning their entry to the downtown areas, basing it on the license plate number of the vehicle.

This is an idewould be a difficult idea to impose and even more to watch by the polilement and would require a greater police presence, since there are so many people in big cities who own twomore than one cars.

You are talking hypothetically, you must use could/would; the subjunctive.
Implement makes more sense here and is ‘on the nose’.

With the correction on the last clause, your attempt was fine but this just sounds more natural.

Moreover, changes could be done to the plate in order to avoid restrictions, with little change to be discovered by the police.hich would affect the total effectiveness of this solution.

For all the expressed aboveAccounting for what has been discussed, in my opinion, it would be easier to promote environmentally friendly changes in the city by the means of granting people instead of charging them.

In this sense, users of public transport would benefit from this grant, what in turn would improve this service, leading to an increase in the number of public transport users over the total number of drivers, and finally, a reduction in the contamination in big cities.

Almost perfect sentence, well done.

Recently I heard a radio debate about the need tof reducinge contamination in big cities, especially from vehicles in downthe center of towns.

Good writing is: simplify, simplify, simplify

Basically, two solutions were exposed in thishe radio discussion: offeringed two solutions: a public transport discount for all ages or chargingriders and having a fee to drivers in the city centre.

As regards the last measure, I completely agree with some the participants who remarks thatI agree with charging a fee to drive downtown; it would be an expensive one, although, but not economically.

This sentence is not clear. What do you mean by "but not economically"

I mean, tThis will be an unpopular measure (synonyms?.

), which will makes it non-effective in terms of durability, since political parties would not support the negativviable in the long run; political parties will have trouble deffects of it ending ant election processtime.

In the debate I hearSpeakers suggested that cars arepresent the first the main source of pollutantsion in big cities, so it was proposed banning their entry to the downtown,; they proposed a plan for allowing cars in the city center basinged on the license plate number of the vehicle.

This is an ideawould be difficult to impose andntroduce, even more to watch by the police, since there are soenforce, since many people in big cities who own two cars.

Moreover, changes could be done to the plate in order to avoid restrictions with little chaPeople could restrictions by alteringe to be discovered by the policeheir license plates.

For all the expressed above,As a result, I suggest it would be easier to promote environmentally friendly changes in the city by means of granting people instead ofthrough positive measures rather than punitive measures; more charging themrot, less stick.

In this sense, users ofPeople who use public transport wcould benefit from this grant incentivized with lower fares, whatich in turn wcould improve this service,. This might leading to an increase in the number of users over the number of drivers, and finally, a reduction in the contamination in big cities.