CA seaside chlorine boosts ozone levels - harms health.

Atmospheric chlorine has a short life , as the chlorine molecules breaks apart just minutes after entering the atmosphere and being exposed to sunlight. Chlorine salts are naturally present in coastal air in sea salt aerosols, it also leaks from treatment plants for water in swimming pools, cooling towers and municipal water supplies.

At the University of California, Irvine they measured chlorine continuously for 2 months, and found levels of + - 5 parts per trillion and sometimes up to 15 ppt - the photochemistry of chlorine at these levels becomes interesting because the chlorine reacts with chemical smog, the mix of hydrocarbons and nitrogen oxides from automobile and power plant emissions, and contributes to the complex chain of reactions that leads to ozone formation. The researcehers could find find (or at least determine) no obvious link between chlorine levels and meteorological conditions such as wind, temperature or relative humidity or existing pollution levels

The primary cause of urban ozone is the reaction of hydroxyl radical (OH) with hydrocarbons and nitrogen oxides. OH is a highly reactive molecule made of oxygen and hydrogen that forms photochemically in air.

"For the last 30 years, we've known that the hydroxyl radical is the primary cause of ozone," Saltzman professor of Earth system science in the School of Physical Sciences at UCI said. "Chlorine plays a similar role. It doesn't take much chlorine to affect ozone chemistry.".. from this they estimate that chlorine photochemistry creates five to eight parts per billion of the maximum daily ozone level, which in California typically ranges between 40 and 80 parts per billion.

Ozone is important to human health because it is a highly reactive and unstable gas that can damages living cells. Even low levels of ozone can harm the upper respiratory tract and the lungs, causing a cough, throat irritation and reduced lung function, and aggravate the effects of asthma, bronchitis and emphysema.

Saltzman says "Understanding the chemistry of chlorine is important to understanding its role in ozone chemistry, especially in California where air quality is such an important issue."

Saltzman and Brandon Finley, a graduate student researcher in the Department of Earth System Science, published their findings in the current issue of Geophysical Research Letters.