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

(e360.yale.edu)
473 points Brajeshwar | 1 comments | 10 Dec 25 15:25 UTC | HN request time: 0.193s | source
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CGMthrowaway ◴[10 Dec 25 15:44 UTC] No.46219027[source]▶
There was a study published about how much air pollution dropped in NYC during the COVID lockdown. PM2.5 was found to have dropped 36%. However with more robust analysis, this drop was discovered to not be statistically significant. I would caution anyone reading this who is tempted by confirmation bias.

Source: https://pmc.ncbi.nlm.nih.gov/articles/PMC7314691/

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1. bonsai_spool ◴[10 Dec 25 16:03 UTC] No.46219356[source]▶
https://pmc.ncbi.nlm.nih.gov/articles/PMC7314691/figure/f002...

Take a look at their figure, especially in May 2020—the average appears lower, but, more significantly, there is much less variability in May 2020 compared to earlier years.

The authors' model quite strongly includes their preferred confound (secular decrease in PM2.5) but doesn't explore what other covariates could explain the differences between years.

It's fine to say that one should be skeptical, but one contrary report doesn't invalidate an antecedent report, and the structure of a linear model strongly influences an outcome.