In New York City, congestion pricing leads to marked drop in pollution

Original Article ↗ Hacker News Discussion ↗

PM2.5 sources and vehicle emissions

  • Several comments stress that the study is about PM2.5 in general, not “tailpipe pollution.”
  • In dense, rich cities with modern gasoline cars, a large share of PM2.5 comes from brake dust, tire wear, and road dust; tailpipes (especially from diesel trucks, small engines, and non‑compliant vehicles) still matter but are often not dominant.
  • Diesel trucks and buses are repeatedly singled out as disproportionate contributors to particulates and NOx; two‑stroke scooters and older diesels are cited as major problems in developing cities.
  • There is some skepticism about media summaries that attribute PM2.5 primarily to “tailpipes,” but commenters note the underlying Nature paper doesn’t make that mistake.

Electric vehicles, particulates, and tradeoffs

  • Debate centers on whether EVs reduce non‑exhaust PM2.5:
    • Heavier weight and high torque can increase tire wear; EV‑specific soft, grippy tires may worsen this.
    • Regenerative braking drastically cuts brake pad use; some EV owners report almost no measurable brake wear.
  • One cited breakdown: in ICE cars, non‑exhaust PM2.5 is roughly one‑third each from brakes, tires, and road dust; one study claims EVs cut brake dust by ~80% but raise tire dust ~20%, for a net reduction in that category.
  • Some argue actual tire wear differences are modest and dominated by driving style; others say EV tires do wear noticeably faster. No consensus, but most agree EVs are still better on local air pollution overall, especially vs diesel.

Interpreting the congestion‑pricing results

  • Multiple commenters emphasize the paper finds little change in car/van/light‑truck entries to the zone; the big drop is in heavy truck traffic that previously used lower Manhattan as a toll‑avoidance shortcut.
  • This matches planners’ long‑standing claims and is presented as the main driver of the observed PM2.5 reduction.
  • A COVID‑era NYC air‑quality study is discussed: a large apparent PM2.5 drop was deemed “not statistically significant,” prompting arguments over model choice vs obvious physical mechanisms. Some warn against over‑interpreting single studies; others say it’s implausible that huge traffic drops didn’t reduce pollution.

Equity, regressivity, and who benefits

  • One line of criticism: flat congestion fees let the wealthy “buy less traffic” while pricing poorer drivers out, increasing inequality.
  • Counterarguments:
    • Car ownership and especially driving into Manhattan are heavily skewed toward higher‑income residents; only a small fraction of low‑income New Yorkers drive into the zone at all.
    • Revenue is earmarked for transit, which overwhelmingly serves lower‑income riders; low‑income discounts and credits exist.
    • Practically, parking and tolls already limited poor and middle‑income driving before congestion pricing.
  • Skepticism remains about the local transit authority’s ability to spend the new revenue efficiently.

Traffic, urban form, and alternatives

  • Many participants argue the real win is “fewer cars in general” and lower vehicle‑miles traveled, not just cleaner drivetrains.
  • Suggestions include more pedestrian‑only streets in Manhattan, stronger transit investment, and better regional rail; others note US rail and bus systems are often too weak outside the northeast.
  • Some point to remote work as another powerful, underused congestion and pollution lever.
  • Concerns about shifting traffic and pollution to surrounding boroughs are raised; others cite the study’s finding of region‑wide pollution reductions and mode shifts to transit.

Politics, culture war, and framing

  • Several comments note that opposition intensity often increases with distance from NYC; people far away treat it as a symbolic fight over cars, taxation, and “dynamic pricing.”
  • Right‑wing media and national politicians are blamed by some for turning a local technical policy into a culture‑war issue.
  • There is broad agreement that “whatever you tax, you get less of”: supporters see that as a feature for urban driving, critics see a regressive cash grab and fear similar schemes spreading to their cities.