Chapter 01 · The Air
How Nitrogen Dioxide Changed Across NYC After Congestion Pricing Began.
Sixteen months of satellite measurements suggest pollution declined more over Manhattan's congestion zone than over the rest of New York City. The placebo comparison helps separate background atmospheric drift from changes more plausibly associated with the toll.
The seasonal cycle, animated
Sixteen Months of Monthly NO₂, Frame by Frame.
Monthly NO₂ (μmol/m²)
Lighter cream = less pollution. Darker green = more pollution.
Before, after, and change
The Congestion Zone's Footprint in the Air.
The left panels show average NO₂ before and after congestion pricing. The difference map on the right isolates where pollution changed most strongly — concentrated around lower Manhattan and adjacent corridors, rather than appearing evenly across the city.
Before the zone
Jan 2023 – Apr 2024
After the zone
Jan 2025 – Apr 2026
What changed
After minus before
Before / After (μmol/m²)
Change (μmol/m²)
Pixels are TROPOMI satellite cells (~5×3 km). The cordon polygon is outlined in cream. Same calendar months in each window remove seasonal cycles from the comparison.
Where pollution declined most
Change in Monthly NO₂ by Neighborhood.
Each shape is a NYC neighborhood (TLC taxi zone). Greens indicate decreases; terracotta indicates increases. The congestion zone is outlined in cream.
Percent change in monthly NO₂ between the pre and post windows. decrease increase congestion zone
n=263 zones · 95% CI on the citywide gap [−2.26, −1.46] pp · TROPOMI ~5×3 km native footprint
Why this counts as a finding
Background Atmospheric Drift, Ruled Out.
NO₂ shifts year to year for many reasons unrelated to policy. The analysis tests this directly: the same comparison run a year earlier, before the congestion zone existed, shows little comparable Manhattan signal. The post-2025 pattern reflects more than ordinary atmospheric variability.
Placebo change · 2024 vs. 2023, no policy in effect
cleaner more polluted congestion zone
The placebo year. Roughly flat over lower Manhattan — without the policy, the cordon area doesn't show the kind of anomaly that appears in the real comparison. The methods chapter explains the placebo design step by step.
Sorting neighborhoods three ways
Three Ways of Grouping NYC.
To ask whether different kinds of neighborhoods saw different effects, the analysis sorts NYC's 263 zones into thirds along three traits — income, car ownership, and transit reliance. The maps below show where each group sits geographically; the chart that follows compares how the congestion zone's air benefit reached each one.
Neighborhood income
How car-free
How transit-reliant
NYC neighborhoods sorted into thirds for income, car ownership, and transit reliance. Click any map to enlarge. The congestion zone is outlined in terracotta.
Did all neighborhoods benefit equally?
The Pattern Does Not Map Cleanly Onto Neighborhood Wealth.
The congestion zone improved most relative to higher-income, less transit-oriented neighborhoods elsewhere in the city. Lower-income, car-free, transit-dependent neighborhoods often experienced pollution declines similar to the zone itself, producing smaller relative gaps.
This does not suggest the benefits were regressive. Many lower-income transit-reliant neighborhoods saw measurable improvement. The gains were uneven, and some neighborhoods bordering major truck corridors appear to have benefited less than the Manhattan core.
Each row compares a group of neighborhoods to the congestion zone. Bars show how much more the zone's air improved than that group's, with 95% bootstrap confidence intervals. Two reference lines mark the citywide average and the placebo-corrected zone effect.