Reducing Smog in the Eternal City

When you think of the City of Rome, what images spring to mind? You’re probably picturing any number of architectural wonders like the Colosseum, the Pantheon, or the Sistine Chapel. Or maybe you’re imagining a meal of fresh pasta and chilled wine, enjoyed al fresco on one of the city’s rustic cobblestone streets. 

What you’re probably not thinking of is smog. But in recent years, air pollution has become a serious problem in the ancient city. In January 2020, the air quality in the city got so bad that the amount of fine particle pollution exceeded Italy’s permitted limit.  

One of the big contributors to Rome’s pollution problem is diesel. Diesel vehicles, which are still very common across Italy, are huge emitters of greenhouse gases — even those marketed as “clean diesel.” Since Rome has no major industries, the vast majority of their smog is emitted by consumer vehicles.

The negative effects of Rome’s diesel smog isn’t limited to human health; it’s also a threat to the city’s cultural heritage. Italy's Institute for Environmental Protection Research and the Superior Institute for Conservation and Restoration found that 3,600 stone monuments and 60 sculptures were at risk of serious deterioration due to its high levels of air pollution. Famous works of art, like the statue of Emperor Trajan and Bernini's famous Four Rivers fountain, are turning black and crumbling over time. 

The city tested out various policies to cut down on diesel fumes, but citizens were quick to find ways around them. At one point, the city even restricted diesel vehicle circulation to certain days of the week depending on whether their plates ended in an odd or an even number — and many families responded by purchasing a second car that they’d be able to use on alternating days. 

In the end, city officials opted for a more extreme course of action: completely banning diesel vehicles from Rome’s historic center, starting in 2024. But past experience had made it clear that no policy could be effective without public buy-in. So after announcing the ban, the city of Rome reached out to The Decision Lab for help easing their citizens into the upcoming change.

Imagine being told you were going to have to stop driving your car in large swathes of your city. That’s no small ask! You’d probably need a pretty good reason to get on board with that kind of shift — one that was rooted in things that you already cared about. In other words, you’d need it to be aligned with your values.

This was one of the main focuses of the behaviourally informed messaging strategy we designed for the city. Even though Italians do care deeply about the environment, abstract messages and statistics about pollution aren’t usually the most impactful. Instead, we recommended framing the diesel ban in terms that resonate deeply with most Romans. That involves things like:

• Rather than just talking about air quality, appeal to family values and Romans’ wishes to keep the city a safe place for their children and grandchildren to grow up.
• Rather than just talking about damage to statues and monuments, remind Romans of the millennia of history behind their ancient city, and the immeasurable value that they are helping to protect by complying with the ban.
• Rather than just talking about the environmental impact of diesel vehicles, appeal to Romans’ sense of national pride and their desire for Italy to lead the EU in terms of action on climate change.

Other focuses of our recommendations included framing the policy change in gradual terms (e.g. the transition away from diesel cars) rather than in abrupt ones (i.e. the ban on diesel cars). 

Over 3 million Roman citizens were impacted by our messaging strategy — not to mention the thousands of monuments that will be far better preserved for the centuries to come.