Pollution Is Making You Dumb

Maybe it is time to buy that air purifier?

Nov 16, 2023

Everyone knows that pollution is bad for your lungs. And you probably don't care that pollution kills 10 million people every year (link to original research paper). That’s not what I want to talk about. Did you know that pollution is making you dumb every day? Like, you're smarter on days when you weren't exposed to pollution and dumber on polluted days? And that there is a ton of research showing all kinds of terrible effects of pollution beyond just asthma and deaths?

(If you prefer to consume your content in video/audio format, here’s the YouTube video and the podcast for this article.)

Studies Showing Effect of Polution on Performance

I’m just going to give you a list of terrible facts, all backed by research:

Chess players make more mistakes on polluted days (2019 paper)
Stock market returns are lower on polluted days (2016 paper): (Why? Because investors don’t think clearly and make bad decisions.)
Baseball umpires make worse decisions on polluted days (2018 paper)
Politicians use less complex speeches on polluted days (2019 paper)

By the way, all of these are from Western countries whose idea of pollution is way lower than what is considered normal, clean air in India. For example, the research on politicians’ speeches looked at an impact of increase in PM2.5 concentration of about 15 µg/m³. If you’ve been looking at AQI numbers in India (e.g. 900+ in Delhi in recent weeks), here’s a mapping: An AQI 150 roughly corresponds to PM2.5 of 50 to 150µg/m³ and and AQI of 500 corresponds to PM2.5 of 350 to 500µg/m³ but the relationship is not linear.)

In short, be extra afraid if you’re in India.

What About Impact on Regular People?

Ok, so maybe you’re not a chess player, or a day trader, or a baseball umpire, or a politician. Should you still be worried?

Students moving from schools away from highways to schools near highways result in lower test scores, more behavioural incidents, and more absences (2019 paper)
- Do you have a child going to a school in a polluted area? (After doing this episode, I bought air purifiers for my kids to use in their hostel rooms!)
Higher pollution in office buildings is associated with lower cognitive scores (2016 paper). So maybe talk to your boss about investing in an air purification system for the office. If the office already has an AC, then you can buy purification units which work in conjunction with the AC and it works out cheaper than standalone purifiers.

Are There Any Long-Term Harms?

All the examples I gave so far were about short-term drops in performance. The story is worse for the long term!

There is a 3.26 times increase in Alzheimer's for every 10µg/m³ increase in long-term PM2.5 exposure (2019 paper). If you’re not afraid of asthma, be afraid of Alzheimer’s!
There’s a similar study showing increase in Parkinson's disease (2018 paper). If you’re not afraid of asthma and Alzheimer’s, be afraid of Parkinson’s!
Study of 20k elderly women shows that every 10µg/m³ increase in long-term PM2.5/PM10 exposure equivalent to aging by 2 years (2013 paper). Or maybe just be afraid of premature aging, like Yayati.
And if you’re not worried about any of this, but just are interested in cracking the JEE or SAT or GRE, check this out: A study in China concluded that reducing exposure to PM10 to 50 µg/m³ would move the median person to 63% in verbal and 58% in maths scores. (2018 paper.)

Why Isn’t the Government Doing Anything?

I don’t know. But it should. It is claimed that a 10% increase in pollution results 1% point decrease in GDP. (Click the link for many more such statistics.)

Also, it is estimated that pollution causes about 10 million deaths per year. Compare this with the annual deaths due to: Terrorism: 25k. War: 50k. HIV/AIDS: 680k. Murders: 470k. Road accidents: 1.3M. Obesity: 2.8M.

Where’s the Proof? Where are the RCTs?

If you’re the kind of person who refuses to believe anything unless it is proved via a scientifically sound method, you’re in luck! We actually have RCT-ish analysis proving some of these effects.

In New Jersey, when the EZ-Pass system was introduced at toll booths (similar to India’s FASTag system, but more efficient), the amount of traffic congestion at the toll booths went down drastically and as a result, the pollution in the surrounding areas went down. Researchers found that as an immediate result, for people living within 2km of these toll booths, the number of premature births was reduced by 10.8% and the incidence of low-birth-weight babies was reduced by 11.8%. 2009 paper.
- They also found a dose-response relationship. The effect on premature births and low-birth-weight babies was proportional to the distance from the toll booth, proving that the effect was due to the pollution.
Pollution also drives inequality: This study shows that lower pollution experienced by a pregnant mother before and during birth increases the lifetime increase in income and upward mobility of the child! Every µg/m³ reduction in prenatal PM2.5 exposure is associated with a $1,105 increase in income of the baby later in its life. 2019 paper

TMKK

My friend Ashish insists that every article should have a TMKK section, meaning “toh maiN kyaa karooN” (So what should I do about it?).

Here are my suggestions:

Move to a place away from the street
Move to a place to reduce your commute
Buy an air purifier
Plan your outdoor activities based on AQI fluctuations during the day
Have indoor plants
The impact is bigger on older people: so keep them extra protected
Pick a school that is not in the middle of pollution

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