The Brussels LEZ is not just banning old diesels. It’s changing how people get to work. A Belgian academic study has just measured this with a rigor rarely seen in public debate. Here’s what it means concretely for businesses.
The study in brief
In March 2026, three Belgian researchers — Astrid Adam (UCLouvain Saint-Louis Brussels), Pauline Colle and Malka Guillot (HEC Liège) — published “Driving Change: The Impact of Low Emission Zones on Commuting Behaviors”. To our knowledge, this is the first study to measure the causal effect of the Brussels LEZ on commuters’ choice of transport mode.
This is not an opinion poll. It’s an econometric analysis (difference-in-differences) based on data from the FPS Mobility and Transport — a mandatory survey conducted every three years with all Belgian companies with more than 100 employees. Four waves: 2014, 2017, 2021 and 2024. Between 615,000 and 920,500 employees covered per wave, representing 15 to 25% of total employment in Belgium.
In other words: massive data, robust methodology, and results you cannot simply dismiss.
Reminder: Brussels LEZ in figures
For context:
- Introduced in 2018, it is Belgium’s largest LEZ (along with Antwerp since 2017 and Ghent since 2020).
- It covers the 19 municipalities of the Brussels-Capital Region: 161 km², 1.2 million inhabitants.
- 353 cameras scan license plates at entry, exit and within the zone.
- Fine: EUR 350 per violation. Alternative: a day pass at EUR 35, maximum 24 times per year.
- Phase 5, originally scheduled for 2025, was delayed by a Constitutional Court ruling (September 2025). It came into force on 1 April 2026.
Regulations tighten progressively. Today (Phase 5): Euro 5 diesels and Euro 2 petrol vehicles are banned. In 2030, all diesels will be banned. In 2035, all combustion engines.
What the study measures — and what it does not
The study distinguishes three groups of commuters based on their exposure to the LEZ:
- Live AND work within the LEZ (origin + destination in zone)
- Work in the LEZ but live outside (destination = LEZ)
- Live in the LEZ but work outside (origin = LEZ)
It is the third group that produces the most striking results. And logically so: someone living in the zone is exposed to the LEZ 24/7. Not just during office hours.
What the study does not measure: cycling. Cycling mode shares in the FPS Mobility survey are too low in the studied groups (~2%) to draw statistically significant conclusions. This does not mean cycling is not growing (data from the Brussels Cycling Observatory shows +12 to 15%/year), but this study does not cover that aspect.
Key results
Brussels residents who work outside the LEZ: -5.8 percentage points car, +4.9 percentage points train
This is the central result. For people living in the LEZ and working outside the zone:
- The share of car trips fell by 5.8 percentage points (a 7.8% decline relative to baseline).
- The share of train trips increased by 4.9 percentage points (a 40.8% increase relative to baseline).
This is not marginal. It is a measurable and statistically significant shift.
Those who work in the LEZ without living there: little change
Surprise: commuters coming to work in Brussels from outside do not significantly change their transport mode. The likely explanation: they are only exposed to the LEZ during work hours, and their place of residence — outside the zone — is not constrained.
Those who live and work in the LEZ: no change either
For trips entirely within Brussels, the study detects no significant effect. These commuters were already heavy public transport users before the LEZ (car share at 31% vs 70-76% for other groups). The room for improvement was smaller.
Three factors that amplify or dampen modal shift
1. Home-to-work distance
The shift to train is concentrated among commuters whose trips exceed 24 km. Below that, metro, bus and tram absorb the transfer. Beyond that, train is faster and more competitive than car — especially at peak hours.
What we see on the ground: companies with Brussels-based employees working in Walloon or Flemish Brabant are already seeing this transition happen. The mobility budget can support it (Pillar 2: SNCB subscription, combined bike + train).
2. Public transport accessibility
Modal shift to train is significantly stronger (+6.2 percentage points) when the place of residence is well served by public transport (accessibility score above the national median of 24/50).
Conversely, when the workplace is well served but the home is not, the effect disappears. That makes sense: you cannot take the train if there is no accessible station from home.
3. Municipal income levels
This is the most politically sensitive aspect. The decline in car usage is primarily driven by residents of low-income municipalities in northern Brussels. More affluent households, meanwhile, bypass the constraint by purchasing a compliant vehicle — typically switching from diesel to petrol.
What we see on the ground: this is an argument we often hear in discussions about mobility budgets. Lower-income employees are most impacted by LEZ restrictions, and they are also those for whom the mobility budget can make the biggest difference — by funding a transport subscription or bike where the car becomes a burden.
And electrification?
If you think the LEZ is massively driving electric vehicle adoption, the study tempers expectations. It does not detect a significant increase in electric or hybrid vehicle share directly attributable to the LEZ. The dominant movement is replacing diesel with petrol — not electric.
This is important data for fleet managers. The LEZ alone does not trigger fleet electrification. It causes a switch between fossil fuels. Electrification is driven by other levers: tax policy (ATN, deductibility), TCO, and company policy.
What this changes for your business
If you have employees living in Brussels
They are exposed to the LEZ permanently. Restrictions will continue to tighten (2028: Euro 4 petrol banned; 2030: all diesels banned; 2035: all combustion engines). Those still driving a non-compliant vehicle will need to either change their car or change their transport mode.
The mobility budget is the tool that makes this transition manageable. Instead of suffering the constraint, the employee chooses: electric vehicle (Pillar 1), train subscription + bike (Pillar 2), or cash allowance (Pillar 3).
If you have offices in Brussels but employees in the periphery
The study shows this group changes little behaviour. But be aware: Euro standards are tightening. A commuter entering the LEZ with a Euro 5 diesel today will be in violation. The cost to the company: EUR 350 fine per violation, or employees who can no longer come to the office.
Three concrete actions
- Map your fleet’s LEZ exposure. How many employees live or work in a LEZ (Brussels, Antwerp, Ghent)? Which vehicles comply with current and future standards? This is the first step of a mobility diagnostic.
- Integrate public transport into your mobility budget policy. The study shows that train is the primary beneficiary of modal shift. A combined SNCB + STIB subscription costs less than a company car and is fully reimbursable under Pillar 2.
- Anticipate 2028 and 2030. LEZ standards are not a one-off event. It is a trajectory. If your car policy includes 4-year lease contracts, vehicles ordered today will still be in circulation in 2030. Verify they will be compliant.
In summary
The Brussels LEZ is doing what it is supposed to do: it reduces car usage and drives toward train. But it does so unevenly — Brussels residents working outside are most affected, and among them, low-income municipalities bear the bulk of the change.
For companies, this is a clear signal: modal transition is no longer a hypothesis. It is underway, measured, and it will accelerate. The mobility budget is the tool that lets you manage it rather than endure it.
You have employees in a LEZ and don’t know where to start? Next Mobility supports Belgian companies in implementing their mobility budget — from fleet diagnostics to operational policy.