Free radicals in combustion-derived particulate matter

Research studies on wood smoke and other air pollution.

Free radicals in combustion-derived particulate matter

Postby Wilberforce » Mon Aug 18, 2008 3:35 pm

Free radicals in combustion-derived particulate matter
Copper oxide-based model of persistent free radical formation on combustion-derived particulate matter.
Lomnicki et al
We have found that environmentally persistent free radicals (PFRs) are formed by adsorption of substituted aromatic molecular precursors on the surface of cupric oxide-containing particles at temperatures between 100 and 400 degrees C. This temperature range corresponds to the conditions in the postflame, cool zone of combustion, and thermal processes. Depending upon the nature of the precursor and the adsorption temperature, both substituted phenoxyl and semiquinone radicals are formed. The PFRs are formed through a mechanism of initial physisorption, followed by chemisorption via elimination of water or hydrogen chloride, and electron transfer resulting in the simultaneous reduction of Cu(II) to Cu(I) and formation of the PFR. The PFRs are still observable by electron paramagnetic resonance (EPR) after exposure to air for more than a day. Their lifetimes under vacuum appear to be infinite. Other redox-active transition metals such as iron are expected to also mediate or catalyze the formation of PFRs. The properties of the observed radicals are consistent with radicals previously observed on airborne and combustion-generated particulate matter. We propose a catalytic biochemical cycle for both the particle-associated semiquinone and phenoxyl PFRs that result in the formation of hydroxyl radical and other reactive oxygen species (ROS). This suggests that combustion-generated, particle-associated PFRs may be responsible for the oxidative stress resulting in cardiopulmonary disease and probably cancer that has been attributed to exposure to airborne fine particles.

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PFR: Persistant Free Radicals

Postby pm2.5mary » Mon Aug 18, 2008 8:31 pm

Here is the Science News article to go with the paper.

Chimney smoke is cited as a culprit. Newly Detected Air Pollutant Mimics Damaging Effects Of Cigarette Smoke
"A previously unrecognized group of air pollutants could have effects remarkably similar to harmful substances found in tobacco smoke, according to a new report. Inhaling those pollutants exposes the average person up to 300 times more free radicals daily than from smoking one cigarette, the researchers added, noting that the study could help explain why nonsmokers develop tobacco-related diseases like lung cancer."

Great find. University of Louisiana is where the science was done showing wood smoke is chemically active in the body 40 times longer than tobacco smoke.

Good find Woodnyet!
"Particulate pollution is the most important contaminant in our air. ...we know that when particle levels go up, people die. " (Joel Schwartz, Ph.D., Harvard School of Public Health, E Magazine, Sept./Oct. 2002)
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