Low-Emission Zones (LEZs) are at the center of controversy in France, as their suspension is being debated in the National Assembly. Often presented as a tool for making the vehicle fleet more environmentally friendly—potentially at the expense of disadvantaged populations living in outlying areas—they are, above all, a means of promoting sustainable mobility. A recent study conducted in the Grenoble metropolitan area shows that the proportion of the population affected who have no alternative is very small and that they could benefit from targeted support measures.

Several hundred low-emission zones (LEZs) exist in Europe. Their health benefits are well-established, notably including a reduction in cardiovascular diseases linked to air pollution. However, in France—where pollution from fine particulate matter with a diameter of less than 2.5 µm (_PM2.5) and from nitrogen oxides (NOx) causes nearly 40,000 and 7,000 premature deaths per year, respectively—the Parliament is considering rolling back the LEZs.

The most disadvantaged social classes are the ones that would benefit the most from efforts to combat pollution. In fact, they are the most exposed to high levels of air pollution.

However, low-emission zones are often viewed as socially unfair to these populations. They are seen as a tool designed to make the vehicle fleet greener by encouraging the purchase of newer vehicles, which are considered cleaner. Since newer vehicles are more expensive, low-income households—which tend to own more older cars—are, in principle, penalized more severely.

Our research suggests we should look beyond this view. Low-emission zones are, above all, a tool for developing sustainable mobility while addressing and improving public health issues related to air quality. This makes them a cornerstone of the transformation of our urban mobility and calls for a rethinking of our dependence on private cars, which are a source of numerous problems.

In addition to air pollution and its health effects, the widespread use of private cars generates noise, contributes to a sedentary lifestyle (a factor in obesity), and takes up public space. The result is a well-known vicious cycle: the more space allocated to cars, the more limited the alternatives become, and the more residents become dependent on them.

Promote a shift in transportation modes rather than making cars more environmentally friendly

The view that Low-Emission Zones (LEZs) are simply a mechanism for making the vehicle fleet greener dominates the debate, which as a result misses the point.

Low-Emission Zones (LEZs) can be much more than that, because there are other ways to adapt to the restrictions imposed by an LEZ besides purchasing a compliant vehicle: changing one’s mode of transportation (taking public transportation, biking, walking), adjusting travel schedules, or even changing certain destinations are all solutions that are often realistic.

The study we conducted on the Grenoble metropolitan area quantified households’ ability to adapt to this Low-Emission Zone (LEZ). To do this, we analyzed the “Household Mobility in the Greater Grenoble Region” survey (EMC2), which tracks trips (origin and destination of each trip, modes of transportation, purpose of the trip, and equipment) for a representative sample of the region’s population.

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For each mode of transportation, we compared the characteristics (distance, but not limited to that) of trips, particularly trip loops (all trips made between leaving home and returning home). We considered that trips and trip chains made by car that had the same characteristics as those made using other modes could be attributed to those modes.

We also examined the reasons for travel (commuting, errands, leisure activities, medical appointments, etc.). The goal was to assess whether certain destinations within the Low-Emission Zone (LEZ) could be substituted for others outside the LEZ.

First finding: Only 8% of households in the metropolitan area are affected by the Low-Emission Zone (LEZ)—that is, households that own a car with a non-compliant Crit’Air sticker and travel within the LEZ boundaries.

For these affected households, two solutions can be considered. First, a modal shift for 57% of them, with extremely high potential for conventional or electric bicycles; and second, a change in destination for 13% of households. Beyond the improvement in air quality that this modal shift would generate, the health benefits associated with physical activity (walking, cycling, or even walking to and from public transportation) are considerable. In the Grenoble metropolitan area, we show that at least 300 premature deaths per year could be prevented. Most importantly, the bulk of this benefit stems not so much from reduced pollution as from increased daily physical activity.

Ultimately, only 30% of the 8% of households affected across the entire metropolitan area (representing approximately 2% of residents) have no alternative but to purchase a car that is permitted to drive in the Low-Emission Zone. Considering the income level of these households, only 0.4% of the metropolitan area’s population (or approximately 300 to 1,500 people out of 826,000 residents) find themselves in the predicament of being dependent on an old vehicle without the financial means to replace it.

This finding is both concerning and reassuring. It is concerning because these people cannot get by without assistance. And it is reassuring because the number of households affected is ultimately small, and it is possible to provide targeted financial assistance to these households without undermining the ZFE policy as a whole.

While these figures are certainly specific to the situation in Grenoble, they show that cities can adapt, especially if they receive the right support.

The Paradox of Acceptability

An argument often cited to justify abandoning Low-Emission Zones is their lack of public acceptance.

Contrary to the commonly held perception of widespread opposition, our research—based on a representative sample of the population in the Grenoble metropolitan area—shows that only 1 in 4 people there are opposed to it. In other words, three-quarters of the population are either in favor or neutral, and more than one-third even say they are “very much in favor” of this measure.

This poll reveals a paradox: a majority is willing to accept traffic restrictions, provided they are effective and fair, while a minority attracts the media’s attention.

We then sought to identify and better understand the factors influencing the acceptability of Low-Emission Zones (LEZs). However, a surprising yet instructive finding emerged from the analysis: it is not so much whether or not a person is affected by the ZFE that primarily determines its level of acceptability, but rather individual perceptions of the ZFE’s impact on the environment, public health, mobility, and social justice.

However, certain supporting measures can improve this level of acceptability:

• These measures can encourage a shift toward public transportation (development of new lines, park-and-ride facilities, etc.), possibly by making it more affordable (single-fare tickets, lower fares);

• They can also encourage a shift toward cycling (through the development of new dedicated infrastructure).

• This may include financial assistance to purchase a car that complies with the Low-Emission Zone (ZFE) regulations,

• or the introduction of exemptions for certain categories of drivers,

• Finally, creating a service that offers personalized advice tailored to specific situations can help implement modal shift solutions.

The Profile of Supporters and Opponents

Our study reveals a very high degree of heterogeneity in perceptions of the usefulness of these measures, both among supporters of the Low-Emission Zone and among its opponents.

First of all, among the opponents, one group stands out. These are people who could be considered ideologically resistant—opposed on principle to any form of restriction on car use—and who believe that no supporting measures are effective. No matter what is done, these people will remain opposed to Low-Emission Zones.

On the other hand, among opponents, there is another group of people who believe that certain supporting measures are useful: park-and-ride facilities combined with improved public transportation, incentives to switch vehicles or modes of transportation, and exemptions for downtown businesses, for example. These individuals would likely be more receptive to the Low-Emission Zone if these measures were implemented. This group should therefore be a priority for public policymakers.

Among the supporters, too, there are several distinct groups. On the one hand, there are those who are convinced both of the benefits of the Low-Emission Zone (LEZ) and of the proposed supporting measures designed to mitigate its impacts in terms of social justice and to promote a shift toward alternative modes of transportation.

Finally, some people who are in favor of the Low-Emission Zone might withdraw their support if too many exemptions granted to motorists were to undermine the zone’s environmental and health goals.

Socially Just Low-Emission Zones That Help Promote Sustainable and Active Mobility

If we want to ensure the long-term viability and widespread adoption of low-emission zones in France, the supporting strategies will therefore need to be carefully balanced.

The top priority is to explain and inform. It is essential to demonstrate, in concrete terms, the impact of pollution on health (mortality, chronic diseases) and how Low-Emission Zones, as part of a comprehensive set of measures, can improve everyone’s daily life.

The second pillar must be equity. For the Low-Emission Zone (LEZ) to be perceived as fair, support must be provided to low-income households that might be adversely affected by traffic restrictions. This, of course, requires targeted financial assistance, but also the development of reliable alternatives: frequent and affordable public transportation, safe bike lanes and sidewalks, organized carpooling, car-sharing, and a degree of flexibility. Exemptions allowing everyone to enter the LEZ—for example, once a week, as in Montpellier, or for light drivers, as in Grenoble—will make the program more acceptable while having only a marginal impact on its environmental effectiveness.

After the scrapping of the bicycle plan, the elimination of electric bicycle purchase incentives, and the slashing of the budget for social electric car leasing, what would remain of sustainable mobility policies if the Low-Emission Zones were to disappear?

In the face of the health and climate crises, Low-Emissions Zones (LEZs) must serve as the cornerstone of a comprehensive program aimed at rethinking our mobility to free us from our dependence on private cars. Our research shows that alternatives do exist and that they could help reconcile environmental, health, and social goals without penalizing the most vulnerable households.