Fewer Indonesians travelled home for Eid in 2025 than the year before. According to a survey by the Ministry of Transportation, around 146.48 million people were expected to join the annual mudik exodus — down roughly 24% from 193.6 million in 2024. A drop of that size should show up in vehicle traffic at mudik destinations — and, ultimately, in vehicle emissions.
But measuring that is harder than it sounds. To my knowledge, the only accessible data on mudik vehicle counts come from press releases and news reports by the Ministry of Transportation, the toll operator Jasa Marga, and the National Police.
Jasa Marga’s figures, collected at the Ciawi 1, Cikampek Utama 1, Kalihurip Utama 1 (West Java), and Cikupa toll gates between five days and one day before Eid, do confirm a decline: 1,045,330 vehicles passed through during the 2024 exodus versus 1,004,348 in 2025 — a drop of 40,982 vehicles (source: kompas.com).
Toll-gate counts, however, only tell us how many vehicles passed a handful of gates. They say nothing about how many vehicles actually moved within a given city or regency. For that, we need regional data — comparable over time (this Eid versus previous ones) and across space (one region versus another). Only then does the picture become comprehensive.
This is where satellites can fill the gap. Nitrogen dioxide (NO₂) concentrations, measured by the Sentinel-5P satellite and accessible through Google Earth Engine, serve as a useful proxy for human activity and traffic density. NO₂ is closely tied to fossil-fuel combustion — which makes it a reasonable indicator of how much traffic is moving through an area, without the time and cost of collecting field data. The link between NO₂ and vehicle pollution is well established: Huang et al. (2021), in a systematic review and meta-analysis, use NO₂ as a proxy for traffic-related pollution when estimating its long-term effects on mortality.
Method: time window and coverage
I processed average NO₂ emissions over an eleven-day window around each Eid — from seven days before to three days after — using the boundaries of all 514 regencies and cities in Indonesia:
- Eid 2023: 13–23 April 2023
- Eid 2024: 2–12 April 2024
- Eid 2025: 24 March – 3 April 2025
What the data show
Nearly every region in Indonesia recorded lower average NO₂ emissions during the 2025 Eid window than in 2024. The opposite was true a year earlier: during the 2024 window, nearly every region recorded higher average emissions than in 2023 — consistent with the rise and fall in traveller numbers.
The interactive map above displays daily NO₂ emissions for Eid 2023, 2024, and 2025. Hover over any regency or city and a popup will show its emission figures for each period.
Take Kebumen, Central Java, as an example. Its Mean_NO2_2025 — the daily average over the 2025 observation window — was 45.39 µmol/m², lower than in both the 2024 and 2023 windows. This suggests that vehicle movement in Kebumen during Eid 2025 was lighter than in the two previous years.
How did your hometown do?
Visualisations are free to quote in the media with attribution. This is the English version of Melihat Perkembangan Arus Mudik Melalui Emisi.
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