Mexico City was famously labeled the most polluted city on the planet by the United Nations during the early 1990s but, more than two decades on, efforts to improve the air quality for its 20 million inhabitants are advancing.

In recent years, the capital has successfully implemented a range of measures to combat pollution which, according to a 2013 study by the Mexican Competitiveness Institute, likely causes around 1,700 deaths per year in the city.

A four-year Climate Action Program launched in 2008 mitigated six million tons of CO2e (carbon dioxide equivalent) , and in 2014 a new six-year program to climate initiatives was launched to build on recent gains.

Mexico City's minister for environment, Tanya Muller Garcia, has been leading efforts to make the streets less congested, less polluted and more pedestrian friendly.

During this month's Formula E race in the Mexican capital, CNN Supercharged presenter Nicki Shields met up with Muller to discuss how the city is slowly cleaning up its act.

Nicki Shields: You have set an ambitious target of a 30% reduction in greenhouse gas emissions by 2020. How is that going?

Tanya Muller Garcia: We have advanced 38% towards our goals in the Climate Action Program mainly thanks to the introduction of our BRT (Bus Rapid Transport) system.

We have also increased our bike structure. With our public system we have approximately 30,000 trips a day with more than 200,000 users. We are also increasing our bike lane network because we know that if we have more safe bike lanes we will have more trips done by bike.

Something very interesting is that here in Mexico City more than 50% of the trips that we do on a daily basis are less than eight kilometers -- so this is where the bike becomes very efficient.

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NS: We are walking around Chapultepec park. Why have you brought me here?

TMG: This is the largest urban park in Mexico and one of the largest in Latin America.

We are redesigning it. Our first action was mobility within the park -- to prioritize pedestrians, people who come to have leisure time, and taking away space for the cars.

That was a huge transformation we did in making pedestrian areas and having bike sidewalk infrastructure -- it's really putting pedestrians and public space at the top of the pyramid.

We've also implemented solar lighting, and the whole design is more environmentally sustainable -- the internal public transport (within the park) is 100% electric.

Using the park as a public space is really important in Mexico City, where you have such large social differences -- these are areas of real cohesion.

The streets of Mexico City are some of the most heavily congested in the world.

NS: Mexico City was notorious for being very dirty in the 1990s. How has it changed since then?

TMG: In the 1990s, we were considered the most polluted city worldwide and now I think we've improved enormously. That's because we have been monitoring our air quality -- we have more than 300 (air quality monitors) in the city that monitor in real time.

When you have hard data you are able to really develop public policies that allow you to attend the problem in a very responsible manner.

So we still have a challenge with Ozone, like any large city, but we are working on that. I think we still have to be conscious about air quality and the pollutants.

NS: What is the focus now?

TMG: In Mexico City, the most pollutants come from private vehicles -- we have almost 6.6 million in the metropolitan area. Our industry is fairly clean. But if you see the industries surrounding Mexico City -- I think there is still a very big opportunity there for these industries to be much cleaner.

We also have an opportunity with fine particles, so what we are doing is attending to public transport -- and that is what is going to improve our air quality but also have a very positive impact in our climate action program.

NS: What are the main issues around pollution? Is it population or the location at high altitude?

TMG: It's a series of things, Mexico City is in a valley and we are surrounded by mountains, so all the pollution that comes from the northern part of the city kind of stays -- it's difficult for it to disperse. But more than dispersing our pollutions we have limit them, because this has an impact on health, and health affects all of us. Air quality has a direct impact on our health and that's why we're so concerned.

We need to have very aggressive public policies here, but in neighboring states too, to reduce pollutants.

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The public are very conscious about air quality -- for example we have an app which tells people in real time what the air quality is like in their area and has recommendations whether they should or should not do sports in open air. For us it has been very important to inform, because their actions have an impact on emissions and it's a problem for all of us.

NS: And what about the electrification of vehicles in Mexico City?

TMG: We have a program of electric taxis in the city. Also we want to promote the use of private electric vehicles.

I think having a Formula E race in the city is going to have a huge impact. People are very positive and very excited. It's such a good message -- something that is a high-adrenalin sport which is also very environmentally friendly.