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Posts Tagged ‘ozone’


How our foods and fuels drive poor air quality in the tropics

Friday, October 23rd, 2009


Palm oil has garnered a lot of news recently.  It’s an ingredient in many processed foods and, increasingly, is being used to make biodiesel fuel.

One initial concern was the destruction of tropical rainforests and peatlands to create palm oil plantations.  To the extent that these plantations are leading to habitat destruction in places like Indonesia, this threatens species like the orangutan.

In this week’s  early edition of the Proceedings of the National Academy of Sciences (open access), a team addressed a second potential problem:  air pollution, specifically ground-level ozone production.

The news about ozone is potentially confusing, so let me start with a quick primer:

  • Ozone’s chemical formula is O3, which is similar to oxygen we breathe in the air (O2).
  • Ozone is a highly oxidizing molecule, which means that it is harmful to living organisms when it comes in contact with them (such as when we inhale it).  If you have ever been around electrical motors and you smell a pungent odor, that’s ozone.
  • Ozone in the stratosphere (upper atmosphere) is good for life on Earth.  It absorbs ultraviolet light and prevents us from getting skin cancer.   This is the ozone that gets damaged by CFCs and other gases, creating the ozone hole over Antarctica.  Because we do not come into contact with this ozone, we benefit from it’s sunscreen properties without suffering any ill health effects.
  • Ozone in the troposphere (the part of the atmosphere near the ground, so it’s also called “ground-level” ozone), however, is not a good thing to have around because this is the part of the atmosphere that comes in contact with living organisms.
  • Ground-level ozone is often a byproduct of urban sprawl.  It forms when volatile organic carbon (VOC) from vehicles (think gasoline vapor) and vegetation (think the smell of Christmas trees) react with nitric oxides from car exhaust under warm, sunny conditions.
  • It’s a part of the chemical soup we call smog.  This is why we often see code orange or code red days in metro suburban areas like Washington DC, suburban NY, Atlanta, and Raleigh-Durham, NC warning people with respiratory illnesses, children, and the elderly to stay inside.
  • Although there is reason to believe that increasing ozone is connected with the rising incidence of asthma, that link has not been well established.
  • The World Health Organization has recommended exposure limits of no more than 50 parts per billion in any 8 hour period.

The PNAS article indicates that ozone production is a growing threat in palm plantations, which show higher temperatures and levels of VOCs and nitric oxides than adjacent rainforests.

Although the level of ozone in palm plantations is not yet at a level that threatens health, the team used a model of ozone production to suggest that if nitric oxide emissions were to reach levels seen in the developed Western world (which may be expected with further development and auto use), this could lead to ozone concentrations exceeding 100 ppb, which is considered an emergency air quality event.

Bottom line:  In tropical regions, we need to think of how to balance economic development, biofuel production, habitat protection, and–now– human health.   To the extent that processed foods and biofuel production are driven largely by consumption in industrialized countries, we share in the responsibility of dealing with this issue.

Already, some companies like Whole Foods have banned unsustainably produced palm oil to combat habitat destruction, but this doesn’t solve the new issue of air pollution.  The article suggests that new varieties of palm plants that emit much lower amounts of VOCs could solve this problem.  That’s good news.

Photo credit: / CC BY 2.0

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