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Is Marin County a "Blue Zone"? For sure!

Blue Zones caught my attention back in 2002 when I read The Okinawa Program. Recently, I viewed Dan Buettner's excellent Netflix documentary How to Live to 100.

The first question that crossed my mind is:

Should Marin County be designated a Blue Zone?

And, if it does deserve this label it would represent a significant achievement. This is because in Marin County, we live in a modern world of convenience, chronic stress, and long hours of sitting.

The five original Blue Zones have a completely different lifestyle. The majority of them live in a pre-agricultural revolution time. They grow their own food. They cook everything from scratch. They do not seem motorized. And, they walk all day long. They don't seem to have computers, TVs, etc.

I knew that Marin County has a very long life expectancy. As a first cut, I wanted to match up its life expectancy vs. the Blue Zones. I also included the life expectancy for Italy and Japan. If entire major countries could deserve the Blue Zone label, they are the ones with the longest life expectancy (for countries with more than 10 million people). They also encompass the location of 2 out of the 5 original Blue Zones. I also included the US as a benchmark of mediocrity. The US makes any region or country deserving of the Blue Zone label look very good.

So, here is how the different regions compare regarding life expectancy.


Notice that I could not get any hard data whatsoever on the Blue Zones. And, that was even after making several data requests to Dan Buettner's organization Blue In contrast, I was able to get extensive time series data from the UN Population Division for countries at our World in Data. And, I got county-level data from the Institute for Health Metrics Evaluation (IHME) at the University of Washington and the National Center for Health Statistics (NCHS).

When you look at the life expectancy comparison, several concepts jump at you:

So, how does Marin County make it into the Blue Zone range? I intuit that Marin County demonstrates that a modern lifestyle can be healthy. It just has to integrate vigorous activities and sports that the Blue Zones do not do. Marin is a mecca of sports including biking, hiking, running. etc. Marin County benefits from a mild climate with a location and topography that allow us to enjoy outdoor sports year-round. Additionally, Marin County is pretty health-conscious. We have numerous organic grocery stores. You don't see anyone smoking. And, you see plenty of pretty fit people (many with gray hair).

So, Marin County is a Blue Zone. And, Marin County is far from alone. There are 9 other counties with a population of more than 15,000 that have a longer life expectancy than Marin County. Notice that four of them are in Colorado, one is in Utah, and another one is in Wyoming. That suggests that mountains are good for you (thank you, Mount Tam!).

Ranking.pngI derived the above ranking leveraging the excellent data from the University of Washington Population Health Institute. I excluded counties with a population of less than 15,000 because smaller samples are associated with large error margins. I am positive one could identify tens of other Blue Zones in Japan, South Korea, Australia, New Zealand, Canada, and Western Europe.

Next, let's look at some interesting time series data comparing Marin vs. Italy, Japan, and the US. I used a LOESS model to construct curvilinear trends with a 99% confidence interval to smoothen out the bit of volatility in the data. I also added a Marin - Asian subset to uncover an interesting ethnic matchup with Japan.


Whenever a time series graph has more than four lines and some of them cross over, the visual information can be confusing. For clarity, I used a clearer facet graph shown below.


The graph above suggests that if we consider Italy and Japan as two reliable standards of Blue Zone countries (associated with solid data from the UN Population Division), Marin has to be considered a warranted Blue Zone (data from: 2000 - 2019 IHME; and 2020 - 2021 from NCHS).

So that case is settled. Marin County is a Blue Zone. As stated earlier, Marin County is not alone. There are 9 other US counties with a population of more than 15,000 that have a longer life expectancy than Marin.

Next, let's explore the relationship between income and life expectancy.

Income vs. life expectancy within Marin County

One expects that there is a very strong positive relationship between income and life expectancy. Let's study this assumption by looking at Marin County's different ethnic groups.

The scatter plot below gives us visual information on this relationship for the different ethnic groups (I used a LOESS model with a 90% Confidence Interval to capture some of the uncertainty associated with small samples). The visualized data is associated with an underlying time series of 7 annual data points from 2013 to 2019.


The scatter plot above gives us a lot of information, but it is overwhelming. So, I am going to split it up so we better understand what the visual data is conveying.

Let's start by focusing on the income vs. life expectancy relationships that are associated with a negative sign. That is contrary of what we would expect!


On the left-hand graph above, you can explicitly see that when focusing on Asians vs. Whites, the Asians with the lower median household income have a much longer life expectancy.

The right-hand graph is even more spectacular. Hispanics have only about half the income as Whites, yet they have a much longer life expectancy! This is convergent with the Blue Zone theory that not-so-modern lifestyles are most favorable to long life spans. The Hispanic community often does outdoor physical labor. As a result, it is a lot more active throughout the day than the White community engaged in white-collar professions sitting at a desk the majority of the day.

Next, let's compare the Hispanic to the Black community.


The graph above shows that there is no relationship between income and life expectancy when comparing these two ethnic communities. Expect for one single outlying income data point, where Black households earned just about $40,000, all other income data points overlap within the range of $50,000 to about $65,000. And, regardless of income within this range, Hispanics have a life expectancy that is about 6 years longer than Blacks. In other words, when focusing on these two ethnic groups, knowing the income level gives you no information at all regarding life expectancy. The determinant of life expectancy here is clearly the ethnic group.

Of course, if we study the other relationships with Blacks vs. Asians or Whites, we would observe the expected strong positive relationship between income and life expectancy.

Does this entail that in Marin County, Blacks are more affected by discrimination than other minorities (that actually fare better than Whites on life expectancy)?

A recent study UC Berkeley study on segregation suggests this could be the case. They stated that Marin was the most segregated county in the Bay Area. Given that most Blacks live within Marin City, you can readily explain how the geographic - math would confirm that Marin County is the most segregated county in the Bay Area. But, does this entail that greater segregation leads to lower life expectancy for the Black community in Marin?

The answer is a resounding no. Blacks in Marin County have a life expectancy that is about 4 years longer than for Blacks in California or the US.


Maps of California and the US both show that Blacks in Marin have one of the longest life expectancies Statewide and Nationwide (light orange = 79 years).




Blue Zones, life expectancy