You’re conflating different results.
The results of the headline study are dramatic in ways that aren’t holding up. The test score increase happened after a single year of putting air filters in class rooms. That’s minimal exposure to purified air for a fraction of the day, 5 days a week, for less than a year of classes.
The other studies are much longe term and look at things like decades of exposure at city scale.
Do you see the difference? The study tried to claim that purifying air immediately improved test scores by dramatic amounts.
There are other serious limitations in the study, like the fact that they can’t even identify which air purifiers were installed or how effective they were. There’s a footnote that says many weren’t even used. There’s a section on air quality monitoring that says they didn’t even detect the VOCs they were trying to filter before they started filtering.
This is the type of study that people implicitly believe because it makes logical sense, but when you read the details you realize that there isn’t much substance in it.
