Newsletter #148: Air Pollution & Green Space 🏭🌳
Happy weekend friends, and welcome to the latest edition of the humanOS newsletter!
This week, we zeroed in on the impact of air quality on human health and performance. It has been well-established that long-term exposure of air pollution increases the risk of cardiovascular disease and chronic respiratory conditions.
However, we are learning that even short-term exposure to particulate matter can result in acute effects on markers of health but also on mood and decision-making, which in turn can affect the economy and crime. For example, one recent study found that a 10% reduction in daily PM2.5 and ozone could save $1.4 billion in crime costs per year.
On the other end of the spectrum, we also looked at beneficial effects of green space, which may partially insulate humans from the deleterious impact of air pollution. Green space may help directly, by boosting exposure to diverse microbes, or indirectly, by facilitating physical activity and other healthy lifestyle factors (or maybe a mixture of both). It is entirely possible that increasing green space and controlling air pollution may jointly make us healthier, happier, and even enhance moral behavior.
Scroll down to learn more! 👇🏼
This Week’s Research Highlights
🌳 Air pollution is linked to poorer blood sugar control - but green space may help offset it.
Researchers analyzed data on various markers of blood glucose homeostasis from participants in the Henan Rural Cohort (n=35482). Exposure to air pollutants (PM1, PM2.5, PM10 and NO2) were predicted by using a spatiotemporal model-based on satellite data, and residential greenness was determined by Enhanced Vegetation Index (EVI) and Normalized Difference Vegetation Index (NDVI), which were derived from satellite data. The researchers found that exposure to various air pollutants was positively associated with fasting plasma blood glucose, and negatively associated with insulin and β-cell function. However, greater residential green space showed the opposite association, and living in higher green space appeared to counteract the negative impact of air pollution on blood glucose homeostasis.
🏡 Higher exposure to residential greenspace in childhood is associated with a reduced risk for inflammatory bowel disease.
Researchers conducted a retrospective cohort study using linked population-based health administrative and environmental data sets (n=2715318 mother-infant pairs). Exposure to residential greenspace was quantified, and potential associations between greenspace and risk of developing inflammatory bowel disease (IBD) before the age of eighteen was analyzed. The researchers found that greater residential greenspace was associated with lower risk of developing pediatric-onset IBD (including both ulcerative colitis and Crohn’s disease). Across increasing quartiles of greenspace, there was a linear dose-response (meaning more green space = lower risk).
🏭 HEPA air filters can reduce levels of indoor air pollution and improve blood pressure of residents.
Researchers recruited 77 participants and randomly assigned them to attend three exposure sessions - each 2 hours in duration - separated by one-week washout periods. During these sessions, each participant was exposed to high, medium, and low concentrations of traffic-related air pollution in a room near an interstate highway. Levels of air pollution in the room were manipulated using portable HEPA air filters and windows. Particle concentrations were monitored continuously, and blood pressure was measured every ten minutes. They found that higher levels of air pollution were associated with higher blood pressure, in a dose-dependent manner.
These increases in blood pressure were relatively small, but could be clinically relevant if sustained over time. If you are spending a lot of time at home (like many of us are nowadays due to the pandemic), a good portable air filter might be a worthwhile investment in your health, especially if you live close to busy roads.
🚨 Air pollution has a significant impact on crime.
Researchers estimated the effect of air pollution on crime using a unique data set, which combined readings of ambient air pollution concentrations with rich administrative records on over 1.8 million criminal offenses recorded in London during 2004-2005. They found that air pollution had a positive and significant impact on overall crime. Specifically, the results showed that an additional 10 Air Quality Index (AQI) points increased the crime rate by 1.2%, and experiencing an AQI of above 35 would lead to 3.7% more crimes. The latter result is similar to the estimated effect of a 10% decrease in police activity. Air pollution seems to especially increase crimes that are spontaneous, rather than premeditated, and the researchers speculate that this effect may be driven by greater discounting of likely future punishment. Reduction in air pollution has been proposed as one potential explanation for falling crimes rates over the past few decades for this very reason. However, this study found that the impact of air pollution on crime occurs at levels that are well below current regulatory standards, suggesting we may yet have some room for improvement.
🧠 Short-term variations in air quality may affect decision-making.
Researchers recruited 611 students in Beijing, who were randomly assigned to visit the lab to participate in a battery of cognitive testing on one of five days. Importantly, it was later determined that levels of ambient PM2.5 varied tremendously on each of these days, and participants were unaware of these fluctuations, meaning that this experiment wound up providing a unique opportunity to identify the effects of air pollution on aspects of cognition. Sure enough, participants who visited the lab when levels of particulate matter were higher showed significant differences in decision-making. In tests of individual decision-making, they exhibited increased risk aversion and ambiguity aversion, seemingly driven by greater pessimism. In tests of social decision-making, subjects became less prosocial; they were less willing to give money to others, and they contributed less money in a public goods game. Air pollution does not merely affect physical health - it also clouds decision-making and likely affects social and economic outcomes through its subtle impact on the brain.
Question of the Week
🤔 Isaac Newton is best known (rightfully) for his seminal contributions to mathematics, optics, and mechanics. However, he also dabbled in eschatology, the branch of theology concerned with “end times.” When did he forecast the end of the world?
💡 Answer
Podcasts We Loved This Week
- Herman Pontzer: How we really burn calories, lose weight, and stay healthy. Via Nourish Balance Thrive.
- Ken Paller: Memory and the dreaming mind. Via Science Friday.
- Sinduja Srinivasan and Anna Rothschild: How variants complicate everything. Via Podcast-19
Products We're Interested In
LEVOIT H13 True HEPA Filter Air Purifier
I have used this air purifier for my bedroom for a couple years and I really like it. It is small, relatively quiet, energy efficient, and economical (both the unit itself and replacement filters are pretty cheap). Bear in mind that the area coverage for a little purifier like this is only 129 square feet at most, so
I definitely wouldn’t count on it to clean your entire home, or even a substantial portion of a house. It’s great for gobbling up allergens, dust, mold, etc in a small space though.
humanOS Catalog Feature of the Week
How-to Guide - Indoor Air Quality
There isn’t a whole lot that you can do individually about outdoor air pollution other than stay inside when levels of pollutants are high (or move somewhere with cleaner air I guess?).
But the indoor environment has its own perils. Indeed, the EPA has estimated that concentrations of certain recognized air pollutants can be 2-5 times higher in indoor environments than outdoors, due to compromised dilution capacity in enclosed spaces. And fortunately, indoor air is much more actionable.
In this How-to Guide, we identify the main types of indoor air pollutants and go over what you can do to mitigate or eliminate them, as well as some fact-checking on a very popular (but scientifically dubious) method for purifying indoor air.
This is obviously a relevant concern for those of us who work in offices most of the day, but it's also key if you're a member of the WFH brigade. One recent study that installed air monitors in the homes of people working remotely during the pandemic found that fine particulate matter levels in the homes of every single participant exceeded air quality standards established by the EPA for a healthy work environment.
That's why we created this guide. It will show you how to test indoor air quality, and support maintenance of better air quality in your indoor spaces, for a healthier body and sharper mind.