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In case anyone else wanted to quantify "huge": > “Polluted air can cause everyone to reduce their level of education by one year, which is huge,” Yale School o

• tw1010 8y ago
  My experience with some PhDs would suggest too much schooling might have the opposite effect...
• Bartweiss 8y ago
  I'm glad Chen attempted to give an intelligible quantity, but I'm not really sure what to make of the metric. "Years of education" don't seem like an intuitive metric for cognitive impairment. Checking the abstract gets us: > Cutting annual mean concentration of particulate matter smaller than 10 μm (PM10) in China to the Environmental Protection Agency’s standard (50 μg/m3) would move people from the median to the 63rd percentile (verbal test scores) and the 58th percentile (math test scores), respectively. For reference, another study in China found that top-decile levels of lead poisoning (>10 micrograms per deciliter) cost children about two points of IQ on both math and verbal scales. That's not trivially convertible to percentile performance, and I don't know whether air pollution has long-tail effects anything like the horrible long-tail on lead poisoning. But it does suggest that particulate pollution has effects on the same general scale as childhood lead poisoning, which is pretty striking. Underlying study is here: http://www.pnas.org/content/early/2018/08/21/1809474115 http://www.pnas.org/content/early/2018/08/21/1809474115 Lead study is here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3667072/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3667072/
  • r00fus 8y ago
    I'd say that a "year of education" is a lot more quantifiable to your average person than "2 points of IQ". IQ isn't used for anything meaningful in terms of ability or qualifications, especially since it's age-adjusted and historically has been biased against minorities/foreigners. A year of development however, is a graspable (if shocking) measure of lost opportunity/capability.
    • SketchySeaBeast 8y ago
      I hope it's a year of my art degree. 2nd year didn't teach me a lot.
    • aero142 8y ago
      Yes, but I'm confused about the truthfulness of the statement. Is it true that an additional year of education is equivalent to 2 points of IQ?
      • jcranmer 8y ago
        The original IQ tests were used to gauge what was termed "mental age", what age you were functionally acting at, and was a ratio of your mental age over your chronological age times 100--a ten year old working at an eleven-year old's level had an IQ of 110. That said, modern IQ doesn't use that definition, and all of the material you can easily find on the matter pretends that it does. Instead, IQ is a normalized bell curve, every 15 points is another standard deviation on the bell curve. Given that definition, a year's worth of education is probably guesstimated at roughly one standard deviation of IQ. This comes with the massive caveat that IQ and educational achievement can't be compared in that manner (since one is an absolute scale and the other is definitionally a statistical artifact).
    • pavelrub 8y ago
      I disagree. "A year of education" is mostly about gaining knowledge. It's obvious that air pullution can't possibly make you forget one year of such knowledge, and I have no idea in what other intuitive way this can be interpreted that makes any sense to the average person. If it's meaningfull to someone then it's only because he understood it wrongly.
      • yorwba 8y ago
        > It's obvious that air pullution can't possibly make you forget one year of such knowledge, Is it? What people remember of one year of education is probably very little to begin with and it only gets less over time; it doesn't seem unbelievable that pollution could cause those memories to decay faster.
  • ip26 8y ago
    "So-and-so third grader reads & does math at a second grade level" is about the most intuitive metric we've got.
    • Bartweiss 8y ago
      It's a very easy way to talk about childhood progression under compulsory education, yes. But if not everyone is in school then I don't know whether "losing a year" means losing the schooling, or losing the year of development. More crucially, the main result here was about older adults losing capacities. If someone tells me that a 70 year old dementia patient has effectively "lost a year of education", I don't have any idea what I should expect.
      • trobertson 8y ago
        You might consider other metrics, like the school grade level that most journalistic entities write for. In the USA, it used to be that most journalists wrote towards a 5th grade reading ability. Assuming that the article is correct, then many journalists who sell to air-pollutant-exposed people (which is most people) should be targeting a 4th grade reading ability, perhaps even lower. On a wild tangent, there has been a huge increase in clickbait over the past several years.
        • Bartweiss 8y ago
          This got me curious: are most Americans exposed to these pollutants at a meaningful level? In short: no. In long: This study was done in China, and asked "what would happen if we lowered 10 micron particulate pollution levels to the US EPA standard?" Air pollution in China is substantially worse than in the US, and 10 micron particulates (PM10) are one of the largest points of divergence: China relies heavily on unfiltered coal burning for electricity, as well as conducting mining and road construction with minimal particulate control. Unfortunately I can't get the API data appendix for the study, and the paper's figures are functions of mean API, but the data shouldn't be paper specific. All sources I can find agree: fine particulate pollution levels in China are horrifying. Almost all of China is consistently exposed to more than 40 micrograms per cubic meter of PM10 particulates, and urban centers are consistently much higher. Recent progress has lowered average rates in many cities into the 40-100 microgram window, but in 2010 annual average rates commonly exceeded 150 micrograms, which is the acute (24 hour) threshold set by the EPA. The benchmark value in the study was 50 micrograms per cubic meter, which was (until 2006, when the standard was scrapped), the EPA's safe limit for annual average exposure. In America, across several hundred sites monitored in 2017, zero exceeded 100 micrograms, only four exceeded the 50 microgram threshold, and only twelve exceeded 40 micrograms. For 2016, those numbers are zero, four, and ten. The hardest-hit sites are all in the Southwestern US, which suffers from both dust and wildfire particulate matter frequently. Further, not all PM10 particulates are created equal. They're grouped in a single number because the usual focus of concern is inhalation leading to lung problems, but when discussing cognitive effects they're almost certainly not equivalent. In particular, PM2.5 (2.5 micron particles) are a subset of PM10, and are both more likely to enter the bloodstream and more likely to be bioactive substances like metal, organics, or soot. Particulates between 2.5 and 10 microns are more likely to be dust, pollen, or ash - damaging to lungs, but much less likely to cause systemic harm. This study did admirable work controlling for or disproving confounders - I'm genuinely very impressed by how well they covered that base. But the PM10/PM2.5 conflation was inescapable since PM2.5 is a subset of the variable and wasn't measured separately. (The study relied on an Air Pollution Index observing sulfur dioxide, nitrogen dioxide, and PM10, with the value controlled by the highest subfactor. From the references exclusively to PM10 and from China's other data, I assume that it was consistently the dominant factor, as it is in the US, but if it correlates with the other factors then one of them could potentially drive the effect. Nevertheless, SO2 and NO2 are essentially acute-only problems in the US, with average rates well below EPA thresholds.) The highest-PM10 sites in the US look prone to dust and ash pollutants, and indeed checking the data says that their PM2.5 levels, while high, trend linearly up from other sites while their PM10 levels rise exponentially. The worst PM10 sites have PM2.5:PM10 ratios of around 20%. The highest PM2.5:PM10 ratios are between 50% and 70%. These are predictably found in industrial Rust Belt cities like Dearborn and Steubenville, but the total levels are still relatively low. 13 cities exceeded the annual EPA standard of 12 micrograms, and none exceeded 17 micrograms. 21 cities had 98th percentile rates in excess of the EPA daily standard of 35 micrograms; excluding outlier Phoenix (146 micrograms) the highest was 67 micrograms. Meanwhile, China's PM2.5 rates have only recently been measured, but are terrifyingly high. China sets 0-35 micrograms as a Grade I success and 35-75 micrograms as Grade II success. Wuhan, selected as an average Chinese city for a study in 2013, exceeded the Grade II standard 75% of the time, and exceeded 150 micrograms (which, again, is the acute PM10 threshold!) 25% of the time. National samples show all cities profiled have PM2.5:PM10 ratios above 50%, and some exceed 80%. Most days in most cities in China, the PM2.5 level is higher than the highest observed rates for any site in the US except Phoenix. Where does this leave us? China's PM10 rates are vastly higher than the worst American rates. China's PM2.5 rates, which are likely more relevant, are even more divergent. Annual NO2 and SO2 rates in the US are insignificant. The available evidence suggests that under any plausible shape for this effect - linear or exponential, threshold or LNT - its effects would be immeasurable anywhere in the US except perhaps 2-3 weakly affected cities. In all cases, other known impairing pollutants like carbon monoxide would be far more impactful. This has been quite a tangent, but overall it's increased my appreciation for this study, while leading me to believe this result is basically irrelevant to US analyses.
• Bartweiss 8y ago
  And to quantify pollution: the study looks at reducing 10 micron particulate pollution in China down to the EPA-approved limits, which almost all US cities are already below, and which Chinese cities are often 2-3 times above. I tried to take a serious stab at "what does this mean for air in the US?", and my best conclusion is "probably almost nothing". The full notes are here: https://news.ycombinator.com/item?id=18231784 https://news.ycombinator.com/item?id=18231784