Air Pollution Makes You Fat

air pollution in china shanghai leads to this?According to a new study recently published this week by researchers at Ohio State University, exposure to polluted air can lead to an accumulation of abdominal fat and contribute to diabetes.

This week we’ll look at the implications of this study to Shanghai residents and what you can do to reduce your risk.

“This is one of the first, if not the first, study to show that these fine particulates directly cause inflammation and changes in fat cells, both of which increase the risk for Type 2 diabetes” – Qinghua Sun, Ohio State associate professor and lead author

Exhaustive research has long demonstrated the health risks of exposure to fine particulates in the air.   Fine particulates (those smaller than 2.5 microns, or about 1/30th the diameter of a human hair) pose the greatest threat because they can easily penetrate past our respiratory systems’ defenses (nose hair, mucous membranes) and be inhaled into the deepest parts of our lungs.  Our bodies’ reaction to the foreign objects causes respiratory difficulty, triggers allergies and asthma attacks, taxes our immune systems, and also increases blood pressure, a major contributor to heart attacks.  Other studies have correlated high levels of particulate matter in indoor air to reduced  birth size and weight, particularly in male infants.

But, the new study has found that fine particulates can also cause more fat cells and higher blood sugar levels.  Juvenile mice were fed  either a normal or a high-fat diet, and exposed to either filtered air or air with high levels of fine particulates.  After 10 weeks, the mice were measured for risk factors for obesity and diabetes.  As expected, the mice on high-fat diets got, well, fatter.  But, the mice on regular diets breathing polluted air had higher levels of abdominal fat and insulin resistance than the mice on the same diet with filtered air.  ”These findings suggest that fine particulate pollution exposure alone, in the presence of a normal diet, may lead to an increase in fat cell size and number, and also have a proinflammatory effect,” said Sanjay Rajagopalan, senior author.

What is worrying is that the levels of fine particulate matter (or PM2.5) pollution used in the study were not 10, 20, or 30x what you would find under normal circumstances.  Obviously, anything taken to extreme may be bad for you.  However, the “bad” air used for the group of mice that developed obesity had, on average, 111 micrograms of fine particles per cubic meter, compared  to 16 micrograms for the control group.  The US EPA’s standard for PM2.5 is 15 micrograms, very close to the control group.  In other words, the “bad” air was about 7x higher than the standard.  This may seem high, but among the air of residential clients for whom we’ve tested, this is not at all unusual.  Typically, we see elevated levels ranging on average between 80-150 micrograms.

This means that for many Shanghai homes, including some very nice high-end compounds, the indoor air contains the same particulate levels as the air used in the study that is being linked to obesity and diabetes.

What can you do?  Here are a few ways to reduce airborne particulates:

  1. Filter your indoor air.  A quality air purifier will use a high efficiency particulate absorbing (HEPA) filter, which filters 99.97% of particulates down to .3 microns.  Your air can only be cleaned effectively, however, if the unit is capable of cycling the air that is processed.  Look for machines that are rated to clean air in the size of room you are using it at least 4 times per hour.   Read my earlier blog post if you are interested in other considerations of how to choose an air filter or purifier in China.  If you have central air conditioning that recirculates air, consider installing or upgrading your filter — it’s an easy, low-cost way to clean your air.  Look for a minimum efficiency rating value (MERV) rating of 10 to 12, which will trap fine particulates while still maintaining adequate air flow.  More on MERV here.
  2. Clean frequently using a wet wipe that will capture particulates and/or a vacuum equipped with aforementioned HEPA filter.  Without a HEPA filter, all that fine dust will be ejected straight back into your air.  Vacuum drapes and upholstery as well, which traps and holds particulates.
  3. Keep your pets clean and out of the bedroom.  Inevitably, homes with pets also test most poorly for high levels of particulates.  Pet dander, which is also a top allergen, is about 2-10 microns large.  Dander actually is not the hair, but rather dead skin cells.  You can reduce dander with daily brushing of cats and washing of dogs as well as other tips found here.
  4. Limit outdoor ventilation on days where outdoor air pollution is particularly bad.  I like the Shanghai Environmental Monitoring Center (SEMC)’s website because it provides PM10 (unfortunately not the more dangerous Pm2.5), nitrogen oxide and sulfur dioxide, data on an hourly basis.
    Shanghai (China) air quality (particulate, SO2, NO2)

    Hourly data on Shanghai air quality

    Shanghai air quality pollution index PM2.5 particulates

    Shanghai at 4pm, Dec 9

    Looking at the hourly data (very trippy to watch the time-lapse change visual map), we can see that, unsurprisingly, PM tends to spike at peak traffic times in the morning and after work.  If you are able to, keep the windows and doors closed during this time.

  5. Take your shoes off before entering the house and use a doormat.  Sounds simple, but the Asian habit is the right one to follow.  EPA studies have shown this can be effective in reducing up to 60% of airborne contamination.

As a sidenote, I found particularly interesting that the researchers are planning to replicate this experiment with human subject, in where else?  You guessed it, Beijing.  Apparently, they will be looking for subjects to wear personal monitors to gauge pollution exposure.  I just wonder where they’ll find the subjects for the clean air…. :)

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