Also see below:     
High Denver Ozone Level May Spur Warning    [

    Smog May Speed Up Global Warming
    Agence France-Presse

    Thursday 26 July 2007

    Ozone in smog will accentuate global warming this century as it will damage plants and trees that help soak up carbon emissions, a study says.

    Its authors fear a major factor in the climate-change equation has been badly overlooked.

    They say ozone at ground level is damaging the ability of plants to absorb the greenhouse gas carbon dioxide (CO2) and so limiting their ability to act as carbon sinks.

    As a result, more CO2 will build in the atmosphere instead of being taken up by the land, which in turn will stoke global warming and thus worsen climate change, the researchers report today online in the journal Nature.

    In the stratosphere, a thin, naturally-occurring level of ozone is a vital shield for life on earth, providing a shield against DNA-damaging ultraviolet.

    But at ground level, it is a pollutant, brewed in a reaction between fossil-fuel gases and sunlight.

    Ozone has long been known to be a risk to health by damaging the airways, but recent research has also highlighted its damaging effect on vegetation.

    The gas enters plants through respiratory pores, called stomata, in the leaves. It then produces by-products that crimp efficiency in photosynthesis, leaving a plant that is weak and undersized.

    Efforts to figure out how fast-rising levels of ozone will affect forests have been hampered by a nasty confounding factor.

    The Stomata Factor

    High levels of CO2 and ozone cause stomata to close, which means the plant takes in less of the CO2 that it needs to grow, but also less of the ozone that damages it.

    The new study seeks to unravel these intertwining factors.

    UK researchers built a computer model to simulate the response of carbon sinks around the world in response to ozone levels, from 1901 to 2100.

    They used two scenarios, depending on whether plants were deemed to have high or low sensitivity to ozone.

    These scenarios were vetted for reliability by comparison with an experiment in which trees and shrubs in a Swiss field were exposed to artificially high levels of CO2 and ozone for seven years.

    Under the 'high' plant-sensitivity scenario, ozone diminished land carbon capture by 23% over the two centuries. Under the 'low' scenario, the fall was 14%.

    Lead researcher Dr Stephen Sitch of the Hadley Centre, part of the UK's Met Office, says the study does not estimate the effect of ozone for the 21st century specifically.

    But he says it is clear that there would be a major contributory effect to global warming by 2100 as less airborne CO2 will be captured by the land.

    "Existing calculations of the carbon cycle haven't factored in the negative effect of ozone," he says.

    A rough calculation is that ozone could indirectly add "somewhere in the range of 0.5-1.25 C in warming, according to Sitch.

    Earlier this year, the Intergovernmental Panel on Climate Change gave its predictions of the impact of climate change on global temperature.

    But this prediction is based on concentrations of greenhouse-gases and does not factor in the indirect effect of ozone.

    Unlike CO2, which spreads around the planet's atmosphere, ground-level ozone pools nearer to its source, with North America, Europe, China and India high on the list of polluted regions.

    In pre-industrial times, ozone was 17 parts per billion. Today, it is 35 parts per billion and is on course for 54 parts per billion by the end of the century, says Sitch.

    Go to Original

    High Denver Ozone Level May Spur Warning
    By Kim McGuire
    The Denver Post

    Sunday 22 July 2007

    Cleaner diesel buses and lawn mowers and tighter controls on fumes from gas pumps, paint shops and dry cleaners may be in store for the Denver metro area as a result of the region's failure to meet federal health standards for ozone pollution.

    On Friday, a monitor placed near the former Rocky Flats weapons plant registered 88 parts per billion of ozone, according to preliminary state health department reports.

    The federal health standard is 80 parts per billion of ozone - a key ingredient in smog - in the air.

    If the number holds, the 11-county area around Denver will have violated federal health standards for ozone for the fourth time this year, and likely will regain its dirty-air status this fall.

    It also means the region will have to come up with a new plan to reduce ozone pollution.

    Paul Tourangeau, director of the state health department's air division, said it was too early to tell what the Front Range plan may look like.

    Local leaders will start discussions as soon as this weekend's data is confirmed, Tourangeau said.

    The state must submit the plan to the Environmental Protection Agency in 2008 - after it receives approval from the state air pollution control commission and the legislature. The plan has to identify all the ozone sources in the region and say how they would be cut.

    "We will look at every tool available to effectively lower ozone in the Denver area," Tourangeau said. "It's just too early to talk specifics."

    New Measures Possible

    The actions other regions have taken when not meeting the clean-air standards include retrofitting diesel trucks and buses, adopting California's tough gas-engine standards, according to EPA spokeswoman Enesta Jones.

    Other steps include adding secondary burners to industrial boilers to better combust pollutants, and buy-back programs of polluting equipment, such as lawn mowers and old cars.

    National environmental groups say whatever regulatory changes are adopted, it's unlikely to cause major changes in residents' day-to-day lives.

    "Denver won't see an immediate change," said Frank O'Donnell, president of Clean Air Watch, a Washington, D.C.-based environmental group. "The lights aren't going to go dim, and the gas station won't run dry."

    "Over time," O'Donnell said, "the state will have to impose tougher controls and it will become harder to do things that add to the pollution."

    For example, new industrial plants that add smog-producing emissions would have to seek offsets from plants closing down, O'Donnell said.

    The new plants would also have to have the very best pollution controls available.

    "Eastern states have already taken a lot of these steps and there's been dramatic progress," O'Donnell said.

    In New Jersey, the number of unhealthy air days at its 13 monitoring stations dropped 37 percent between 1997 and 2005 to 106, based on EPA data.

    In Maryland, high ozone days were down 62 percent in the same period to 78 at 16 monitoring stations.

    A rule requiring the best technology to retrofit power plants in the state to cut emissions was adopted by the Colorado Air Quality Control Commission last year.

    While aimed at cutting haze over national parks and wilderness areas, those pollutants also contribute to ozone.

    In addition, the commission also last year adopted tough new rules for ozone-forming pollutants emitted by the state's booming oil and gas industry.

    Despite those measures, ozone levels began to spike in July as hot weather settled in over the Denver area.

    "Meteorology certainly plays a role, which makes our jobs challenging," Tourangeau said.

    Ozone is an acrid gas formed when volatile compounds, from auto tailpipes, power plants and other sources, interact with light and heat.

    The agency recently proposed lowering the health standard standard to 70 to 75 parts per billion.

    Colorado should consider the proposed standard as it begins drafting its new ozone plan, said Vickie Patton, a Boulder-based attorney with Environmental Defense.

    "It provides direct public health benefits to children, the elderly, and people who are active and spend a great deal of time outdoors," said Patton.

    Heat Causing Problems

    Ozone causes chemical changes inside the lungs that result in shortness of breath, coughing and pain, according to the EPA.

    The toxic air can inflame lung tissue and increase risk of stroke and heart attack, according to an EPA report released in January.

    People with asthma, other lung problems and heart ailments are especially vulnerable to ozone's damage.

    About 7 percent of healthy people have shortness of breath with ozone levels at 60 parts per billion, the report said.

    In downtown Denver last year, ozone levels were 60 parts per billion or higher on seven days from June 1 to Aug. 31.

    Health officials said Saturday they expect ozone levels to continue to rise over the weekend as scorching temperatures and stagnant air prevail over the region.

    People are being asked to change their daily habits to keep ozone down - including driving less, using gas-powered lawn mowers later in the day and putting a lid on their paint and household chemicals.

    "From a public health perspective, the numbers we register over the weekend are just as important as Friday's number," said Christopher Dann, a health department spokesman.

    "People should be aware that we're in the middle of an ozone event and should take the necessary precautions," he said.