Ozone and Climate Change: The deadly truth

Ever seen a thick layer of haze hanging over a city in the summer?  That’s ozone.  I remember years back, mountain biking in the summer heat at South Mountain Park in Phoenix, Arizona. I would ride up the mountain until I was eye level with the layer of blue haze.  I used to think, “This can’t be good.”  Maybe that’s why old Doc Goodwell gets a little wheeze every now and again.  Who knows.

Anyhow, the recent proposed change in the U. S. Environmental Protection Agency (EPA) regulation governing ozone has brought it back into the spotlight.  The EPA wants to lower the maximum amount of ground level ozone from 75 parts per billion (ppb), to 65 or 70 ppb.  Of course, conservative pundits and politicians were in an immediate uproar, stating the new regulations would destroy all American industry and take us back to the middle ages, where we would all be ruled by jack booted EPA thugs and tree-hugging hippies.  We’ve all heard this before whenever any new environmental regulation is proposed, nothing new there.

That progressive, Nobel Prize winning economist, Paul Krugman, pointed out in a recent editorial that the same pundits who always claim that the free-market can solve absolutely any problem, also believe that industry will suddenly collapse should this EPA regulation pass.  He points out that the economic impacts of environmental regulations are usually overblown (see a nice little review → here).  And as the EPA points out, despite the passage of the Clean Air Act in 1970, the American economy has tripled in size, while at the same time air pollution has decreased by 70%.  But, beyond the overblown economic impacts, the bad health effects of ozone are real, and are probably gonna get worse with climate change.  How do we put a price on that?  Let’s have a look.

What is ozone and where does it come from?

Ozone is a blue gas composed of three oxygen molecules bonded together.  Two molecules of oxygen bound together (good old “O2”) makes up about 21% of the Earth’s atmosphere, and we need it to stay alive.  Ozone is created high in the upper atmosphere where ultraviolet light and lightning provide the energy to bind that third molecule of oxygen.  Ozone high in the atmosphere is a good thing, because it blocks some of the sun’s ultraviolet rays.  Close to the ground, ozone forms from industrial and automotive exhaust.  Heat makes it form faster.  So as temperatures get warmer more ozone is created; which is why we have more ground level ozone in the summertime.

Ozone is a highly reactive molecule, meaning that it easily combines with other compounds and molecules.  Because it’s so reactive, it irritates and damages your airways and lungs when you breathe it in; and the higher the concentration, the more damage is done.  More ozone is usually found in cities, but can also be found in suburban and rural areas downwind from large cities or industrial sites.

What are the health impacts of ozone?

Ozone irritates your lungs and causes:Young Asthma patient using an inhaler

  •    inflammation of small airways in the lungs
  •    increased obstruction of the small airways
  •    increased sensitivity of the airways

Which leads to:

  •    cough
  •    sore throat
  •    burning chest pain with deep breaths
  •    tight chest feeling
  •    wheezing
  •    shortness of breath

Infants, children, the elderly, people who work outside and people with chronic lung diseases are way more likely to have trouble as ozone levels go up.  Ozone has been directly linked to asthma and emphysema attacks, missed school and work, more visits to the Emergency Department and death.  Statistically, the risk of something bad happening, including death, to any one person is not great, but when you look at large populations of people, ozone is responsible for a lot of sick people.  In other words, YOU might not win the lottery, but SOMEBODY does, and in this case, a whole lot of “somebodies” may win this horrible lottery.

Health Impacts of Ground Level Ozone

Parts Per Billion of OzoneHealth Effect
>10 ppb increase above usual levelsemphysema gets worse
>10 ppb increase above usual levels0.52% more deaths per day
50 ppbreduced lung function in healthy people exercising outdoors
65 - 70 ppbproposed EPA standard
75 ppbcurrent EPA standard
* Data from Union of Concerned Scientists (link below).


How will climate change make ozone worse?

Although ozone levels in the U.S. have dropped over the past several decades, due mostly to the effects of the Clean Air Act, increasing summertime temperatures across the U.S. due to climate change may slow or reverse this trend.  Warming temperatures cause more power to be used for air conditioning, more burning of fossil fuels to power those air conditioners, and thus more ozone created.

A recent study by the National Center for Atmospheric Research, in Boulder, Colorado, used several state-of-the-art climate models and a new supercomputer called Yellowstone to model the increase in ground level ozone pollution.   It found that most of the U.S. will experience a 70% increase in summer days with unhealthy levels of ozone, while the cities that already have some days of unhealthy ozone, will have unhealthy ozone on most days of the summer.

Current average ozone levels are 31 to 79 ppb on average across the country, but are expected to shift to 30 to 87 ppb for about 90% of the summer.  While this may not seem like much, it represents hundreds of thousands more asthma attacks, missed days of work and school, and hospital admissions.  Fortunately, this work also showed that reducing the levels of air pollution also reduces the concentration of atmospheric ozone, despite rising temperatures.

The Union of Concerned Scientists (UCS) put out a great report about the impacts of ozone with rising temperatures.  If you want to read a well done, easy to read scientific report about ozone and climate change, this report is for you.  The UCS study looked at the impacts of warming temperatures on ozone concentration in 40 states in the U.S.  Ten states were left out because there was not enough data to estimate changes.  A “penalty factor” was created for the U.S. as a whole, which links the increase in temperature to a matched increase in ground level ozone.

For each one degree Fahrenheit rise in temperature, ozone increases 1.2 ppb.

The penalty factor was applied to expected temperature increases under best case and worst case climate change scenarios.  The increase in ozone under these different conditions was then put into the EPA’s Environmental Benefits Mapping and Analysis model (BenMAP) to figure out the expected changes in five specific health outcomes: occurrence of acute respiratory symptoms, asthma-related emergency department visits, hospital admissions for seniors and infants, lost days of school, and premature deaths.

Ozone-Related Impacts of Climate Change*

 2020 2050 
Best Case
(+1 ppb)
Worst Case
(+2 ppb)
Best Case
(+2 ppb)
Worst Case
(+7 ppb)
Acute Respiratory Symptoms1,414,7702,825,8503,400,09011,822,430
Emergency Room visits for Asthma6001,2001,4805,190
Seniors admitted to the hospital1,8403,6806,85023,940
Infants admitted to the hospital7101,4201,6605,680
Missed school days471,530943,5601,181,2604,145,280
Premature Deaths2605107502,160
Additional Health Care Costs$2.7 billion$5.42 billionno datano data
* The central, or mean value is shown, which represents the most likely value. Also, this data is ONLY for the years 2020 and 2050, and is not added with prior years; in other words, it’s worse than it looks.

From the Union of Concerned Scientists…

Climate Change and Your Health:  Rising Temperatures, Worsening Ozone Pollution

The Union of Concerned Scientists is “a non-profit partnership of scientists and citizens combining rigorous scientific analysis, innovative policy development and effective citizen advocacy to achieve practical environmental solutions.”

Will climate change make ozone worse where I live?

The Air Quality Index (AQI), which you often see reported on the evening news during the weather report, is in large part a measure of ground level ozone concentrations.  On bad AQI days, where the ozone concentration is high, it is usually recommended that the elderly, children and people with chronic disease stay indoors.  They also usually recommend that people working or exercising outdoors limit their activity.  Ozone concentrations indoors are 20 to 80% of outdoor levels, which is why staying inside is often a good idea on bad ozone days.  The UCS report also ranked ozone impacts by state.  Of course, states with large cities do worse.

Top Five States Impacted in 2020*

RankStatePeople AffectedCost
3New York212,600$391,568,950
* For acute respiratory symptoms and increased healthcare costs. "Worst case" for 2020 used, which gives a 2 ppb increase above baseline ozone levels, strictly due to higher summertime temperatures. For the full ranking of all 40 states, click the link above for the Union of Concerned Scientists report, and look at the "technical appendix".

How’s my air now?  → http://www.airnow.gov/

How’s my air been in the past? → http://ephtracking.cdc.gov/showIndicatorPages.action

What can we do about it?

Besides staying indoors on bad AQI days, there are lots of things we can do to protect ourselves and make the air cleaner.

On a personal level, you can

  • drive less, especially in the summer
  • insulate and weatherproof your home
  • buy renewable energy from your power company (or install it yourself!)
  • walk and bike more
    • but, stay indoors on bad air quality days
    • and if you have to be outside on bad days, limit your exertion
  • move to an area with better summer air quality (drastic but it may come to that)

We can reduce the impacts of ozone on our community and nation by…

  • raise the fuel efficiency standards for cars and trucks
  • create good public transportation systems
  • increase the energy efficiency of industry
  • retrofitting homes and commercial buildings for energy efficiency (it’s not sexy, but this is where the lion’s share is!)
  • use more renewable energy (wind, solar, geothermal, nuclear)
  • support strong environmental regulations (like the one discussed in this article)
  • work to cut carbon emission, from our own, and other countries
  • and be politically active (write your elected representatives)

Besides reducing ozone, it’s crazy how many other beneficial effects these measures have!  Including… saving you money (less gas and electricity to buy), making you skinnier (walking and biking are damn good for you), and making us into an energy independent nation with clean air and water.  So even if you don’t believe in “climate change”, all of these things are just plain good for you, your community and your country!

If you have any ideas to reduce ozone, or your personal exposure to it, please comment below.  Thank you.


(I hope you liked my catchy title for this post.  I was reading one of the many blogs about blogging, and it said you are supposed to use catchy titles to draw in readers.  Hopefully you found this post interesting, informative, and/or entertaining.  And if you did, please consider leaving a comment, and or subscribing.  Thanks!)