Thursday, September 8, 2011
OZONE: BAD NEARBY
Although my niece Megan, good friend's daughter Kate, and son-in-law Andrew may not realize it, they most likely share a sensitivity to ozone air pollution. You see, they each suffer from asthma. They are just three people I know who have asthma, there are others, since asthma is a condition that affects an estimated 20 million Americans, 1 out of every 15 of us. And experiments find that people with asthma suffer greater lung damage when exposed to ozone air pollution than the rest of us. We all suffer lung damage when we breathe ozone, but some of us experience more injury than others.
President Obama recently decided to delay issuing a rule that would have lowered something called the primary standard for ozone air pollution. That primary standard now sits at 0.075 parts of ozone per million parts of air (ppm) averaged over an 8-hour time period. The US Environmental Protection Agency (EPA) proposed lowering that primary standard to between 0.070 and 0.060 ppm of ozone. That would mean cities would have to adopt strategies to keep ozone pollution from exceeding 0.060 or 0.070 ppm averaged over 8 hours.
Just what is ozone? It is a molecule that consists of three oxygen atoms (O3). The oxygen molecule you want to breathe, that you enjoy breathing in deep gulps, has just two oxygen atoms (O2). How do normal, two-atom oxygen molecules acquire that third, troublesome atom? That involves energy, as do all chemical changes, and in this case the energy comes from sunlight. But sunlight alone is not enough. To get O3 from O2, the air must also have other gases present, nitrogen oxides and hydrocarbons.
Nitrogen oxides and hydrocarbons come mostly from burning fossil fuels. Nitrogen oxides are produced when we burn coal in power plants to produce electricity, or burn gasoline in cars and trucks. This is also how hydrocarbons are produced, though hydrocarbons can also come from the evaporation of gasoline and other petroleum products or solvents like dry cleaning fluids.
Sparing you from more chemistry than you need to know, just be aware that those nitrogen oxide and hydrocarbon gases in the air help sunlight split apart some O2 molecules, freeing up two solitary oxygen atoms, which can then each combine with still-intact O2 molecules to produce O3 molecules, ozone. And ozone is a highly reactive molecule, which means that it will react with and change (equals damage) any of your body's cells it comes in contact with.
Your skin cells are made tough to resist chemical attack, and are not affected by ozone. However, the inside of your lungs are not covered in skin cells, they can't be or they would be no good at absorbing the oxygen you need to live. So the cells lining your lungs are readily injured by contact with ozone, which is unavoidable if it's present in the air - unless you hold your breath!
Megan, Kate, and Andrew, and the rest of us too, will suffer damage to the cells in our lungs when we breathe in ozone. Notice I said when, not if. All of us living in the developed parts of the world have breathed in ozone air pollution at one time or another. It's our most common and most important air pollutant - a molecule that is produced in the very air around us.
Experiments show that lungs can begin to respond to ozone concentrations as low as 0.060 ppm, levels often exceeded across the country during the summer months. In fact, the national 8-hour maximum average ozone levels during the summer of 2009 was 0.070 ppm.
We all suffer some level of injury from ozone air pollution. That injury can trigger inflammation and reduced lung function, increased susceptibility to respiratory infection, coughing, sore throat, shortness of breath, and aggravation of chronic lung diseases such as asthma, emphysema, and bronchitis. The costs to health include increased medication use, more frequent doctor visits and school and work absences, increased emergency room and hospital admissions, and even premature death in people with heart and lung diseases.
Ozone is a seasonal air pollutant problem, because it requires intense sunlight and high temperatures. The sunlight, as you know, provides the energy necessary to produce ozone, and the high temperatures speed up that chemical reaction, meaning higher concentrations of ozone in the air.
When you hear news reports of a "Code Orange" air pollution alert, that means authorities expect the sunlight and heat forecasted for the coming day are enough, given the presence of nitrogen oxide and hydrocarbon air pollutants, to produce dangerous levels of ozone air pollution, especially during the hottest part of the day. People sensitive to ozone, people with asthma or heart conditions or COPD (chronic obstructive pulmonary disease) should refrain from physical exertion outdoors to avoid suffering injury. Of course, all of us might do the same to protect our lungs, and if you ever hear a "Code Red" or "Code Purple" ozone alert, stay inside and hold your breath!
The recipe for reducing ozone air pollution involves reducing those "precursor" gases, nitrogen oxides and hydrocarbons. We can't stop the sun from shining, but we can burn less coal and gasoline, and clean up the smokestack and tailpipe emissions when we must burn those fuels.
The estimated costs for reducing those emissions to levels that would keep ozone under the proposed lower primary standard of 0.060 ppm - from $19 to $90 billion by 2020. The estimated health benefits approximately equal those costs, ranging from $13 to $100 billion. So a simple cost-benefit analysis suggests we should do it!
And those health benefits include saved lives and improved quality of life, especially for the 1 in 15 of us who suffer from asthma. Are Megan, Kate, and Andrew worth making that effort? Is your health worth it?