Ozone study raises questions for human health

On any given fire-free day, Idyllwild residents can step out their doors and take a breath of fresh air.

Or can they? How safe is the air we breathe?

A study published in the Journal of the American Medical Association last month suggests that higher ozone levels can be linked to higher mortality rates. And while the ozone level in the San Jacinto Mountains is relatively lower than that of major urban areas, new questions are being asked about the health risks of ozone.

The study, a joint effort by the Yale School of Forestry and Environmental Studies and the Johns Hopkins Bloomberg School of Public Health, states that for every increase in ozone of 10 parts per billion (ppb), there is a corresponding 0.52% increase in the number of deaths reported.

Air quality managers and health care officials have known about the adverse health effects of ozone for years, prompting the Environmental Protection Agency to set a daily maximum 8-hour exposure of 120 ppb for humans. That threshold, however, is based on levels that cause respiratory distress. The study is the first to suggest a direct link between ozone and death.

“We do not know at this point if a threshold (safe level) for ozone exists, or if it does exist what it is,” said the study’s lead author, Dr. Michelle L. Bell of Yale’s School of Forestry and Environmental Studies.

Bell said that her team focused on comparing two-week intervals. Regardless of the level measured – in other words, whether the ozone was 30 ppb that day or 150 ppb – every 10 ppb increase caused an increase in mortality. So even readings below the EPA standard would see an increase in mortality.

“Our study did look at days below an approximation of the EPA standard and found that ozone is associated with mortality, even at those low levels,” Bell said.

Ozone has been of particular concern to scientists studying tree mortality in the San Bernardino National Forest. A team of researchers are looking into the role ozone levels play in weakening or killing pine trees – a possible added pressure, along with drought and overpopulation, to allow the bark beetle to infest trees.The EPA sets the standard for damage to trees and shrubs at 60 to 100 parts per billion, about the same threshold as health effects for humans.

There is one Forest Service monitoring station in the area – located at Red Mountain Lookout, south of Highway 74 and east of Diamond Valley Lake – real time data from it can be viewed at www.fsvisimages.com/SAJA1/SAJA1.html#. The station is currently reporting 14 hours over 100 ppb over the course of the smog season, which runs May to September. The current reading is 17 ppb. That number is well below the standard set by the EPA for causing adverse health effects in humans, however the peak numbers are within the range to affect humans.

These effects include shortness of breath, coughing, and difficulty taking deep breaths.High levels can cause symptoms immediately through breathing, according to Jean Ospital, Health Effects Officer for the South Coast Air Quality Management District (SCAQMD).

“Ozone is a very reactive chemical,” he said. “When we inhale it, it is a respiratory irritant.”

However, symptoms can occur at lower levels when someone is exposed to ozone for a long time, such as exercising or working outdoors. Most studies show some health effects at 80 parts per billion, he said, but recent studies are showing effects at 70 parts per billion.

Ozone exposure is a larger problem for those who live on the other side of the San Gorgonio Pass. Most of the work done by the Atmospheric Deposition Unit of the Pacific Southwest Research Station in Riverside focus on the south facing areas of the San Bernardino Mountains, such as the Lake Arrowhead area and Big Bear area. This is because the prevailing wind patterns tend to blow smog from the Inland Empire up to those areas, said South Coast Air Quality Management District (SCAQMD) senior meteorologist Joe Cassmassi.

Sam Atwood, media office manager at the SCAQMD, said there is no monitoring equipment in the San Jacinto Mountains, a fact confirmed by Cassmassi. Both men were confident that Idyllwild’s air quality was in better shape than the surrounding urban areas of Riverside, San Bernardino, and the Coachella Valley.

“While Idyllwild’s air is not pristine, it should be considerably cleaner than the region’s ozone ‘hot spots’ such as Crestline and Santa Clarita,” Atwood said.

The nearest monitoring station is in Perris, Cassmassi said, though there used to be a station in San Jacinto. That was removed a few years ago, he said, because “for years it was reading very low levels of ozone, maybe 1 day every couple of years in violation of the 1-hour standard.”

A temporary station placed at San Jacinto over the last few years has produced the same readings.

However, Cassmassi explains that a “little bit” of air pollution migrates up from the valley in the form of ozone. This is worse in the summer, when temperature helps ozone rise in the atmosphere.

Which brings us back to Bell’s study. If even small amounts of ozone can cause an increase in mortality, what level is safe?

“If your region has levels above EPA’s standards, then that implies adverse health impacts.” Bell said. However, “We found an association with mortality even at levels below an approximation of the EPA standard.”

Ospital says there are a few things people can do, like staying inside where ozone levels are lower, and avoiding prolonged outdoor activity.

“We generally recommend when ozone levels are high that people try to avoid exercising outdoors,” he said. “Exposure is higher when you exercise because you breathe more and get a higher dose.”

And will Bell’s study force air quality managers to change their approach to mitigating health effects or lower the ozone standard?

“AQMD is mandated by the federal Clean Air Act to meet federal health-based standards for ozone,” Atwood said. “While one particular health study does not change the mandate per se, it does point out that while many studies recently have focused attention on the health effects of fine particulate, ozone still is a health threat.”

The solution, Atwood said, isn’t an individual responsibility.

“Ozone is a regional pollutant and as such must be reduced on a regional and not simply local basis,” he said. “In other words, ozone-forming emissions must be reduced across the entire Los Angeles Basin to reduce levels in Idyllwild.”

Meanwhile, research continues into the effects of ozone on people. Bell said her team’s next project is to find out if there is a safe threshold of ozone for humans. She said the current ozone limits are now in question.

“EPA is mandated by the Clean Air Act to set and periodically review regulatory standards for ozone,” Bell said. “They are currently in the process of deciding whether or not these standards need to be revised and are at the stage of gathering scientific information on ozone and health, so they will be looking at the results of our study and many others.”

Ospital, for one, doesn’t think Bell’s study should cause panic, but should get people’s attention.

“We’ve been concerned about ozone for a long time,” he said. “I don’t think (Bell’s study) over- or understates the problem. I think it showed the links and association that the data showed.”

For those wishing to learn more about clean air practices, Atwood suggests the AQMD’s site www.cleanairchoices.org, and visiting the Ten Things You Can Do To Help Clean Up The Air flyer at www.cleanairchoices.org/ten_tips.htm.