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Ozone and Nicotine Can Form Ultrafine Particulates; Asthma Hazard

A new study by researchers at Lawrence Berkeley National Laboratory's (Berkeley Lab) Environmental Energy Technologies Division (EETD) shows that ozone can react with the nicotine in secondhand smoke to form ultrafine particles that may become a bigger threat to asthma sufferers than nicotine itself. These ultrafine particles also become major components of thirdhand smoke—the residue from tobacco smoke that persists long after a cigarette or cigar has been extinguished.

Smoking Machine

Measuring the emissions of ultrafine particles. (Photo by Roy Kaltschmidt, Berkeley Lab Public Affairs)

A new study at Berkeley Lab shows that ozone can react with the nicotine in secondhand tobacco smoke to form ultrafine particles that may become a bigger threat to asthma sufferers than nicotine itself.

"Our study reveals that nicotine can react with ozone to form secondary organic aerosols that are less than 100 nanometers in diameter and become a source of thirdhand smoke," says Mohamad Sleiman, a chemist with the Indoor Environment Department of EETD, who led this research.

"Because of their size and high surface area to volume ratio, ultrafine particles have the capacity to carry and deposit potentially harmful organic chemicals deep into the lower respiratory tract where they promote oxidative stress," Sleiman says. "It's been well established by others that the elderly and the very young are at greatest risk."

The study's results have been reported in Atmospheric Environment in a paper titled "Secondary organic aerosol formation from ozone-initiated reactions with nicotine and secondhand tobacco smoke." Hugo Destaillats and Lara Gundel, also with EETD's Indoor Environment Department, co-authored the paper with Sleiman, as did Chemical Dynamics Group researchers Jared Smith, Chen-Lin Liu, Musahid Ahmed, and Kevin Wilson, of Berkeley Lab's Chemical Sciences Division. The study was conducted under a grant from the University of California's Tobacco-Related Disease Research Program.

The dangers of mainstream and secondhand tobacco smoke, which contain several thousand chemical toxins distributed as particles or gases, have been well documented. This past February, another study, spearheaded by Sleiman, Destaillats, and Gundel, revealed the potential health hazards posed by thirdhand tobacco smoke, which was shown to react with nitrous acid, a common indoor air pollutant, to produce dangerous carcinogens. This is the first study to show that ultrafine particles form from the reaction of nicotine with ozone.

Released as a vapor by the burning of tobacco, nicotine is a strong and persistent adsorbent onto indoor surfaces. It is released back to indoor air for a period of months after smoking has ceased. Ozone is a common pollutant that infiltrates from outdoor air through ventilation. It has been linked to health problems, including asthma and respiratory ailments.

Advanced Light Source: Chemical Dynamics Beamline

(From left) Musahid Ahmed, Lara Gundel, Kevin Wilson, and Mohamad Sleiman at the Chemical Dynamics beamline of Berkeley Lab's Advanced Light Source. (Photo by Roy Kaltschmidt, Berkeley Lab Public Affairs)

Says co-author Gundel, "Not only did we find that nicotine from secondhand smoke reacts with ozone to make ultrafine particles—a new and stunning development—but we also found that several oxidized products of ozone and nicotine have higher values on the asthma hazard index than nicotine itself."

Says co-author Destaillats, "In our previous study, we found that carcinogens were formed on indoor surfaces, which can lead to exposures that are likely to be dominated by dermal uptake and dust ingestion. This study suggests a different exposure pathway to aged secondhand or thirdhand smoke through the formation and inhalation of ultrafine particles. Also, our group had previously described the formation of secondary organic aerosols in reaction of indoor ozone with terpenoids, commonly present in household products. But this is the first time that nicotine has been tagged as a potential candidate to form ultrafine particles or aerosols through a reaction with ozone."

To identify the products formed when nicotine in secondhand smoke reacts with ozone, Sleiman and his co-authors utilized the unique capabilities of Berkeley Lab's Advanced Light Source (ALS), a premier source of X-ray and ultraviolet light for scientific research. Working at ALS Beamline 9.0., which is optimized for the study of chemical dynamics using vacuum ultraviolet (VUV) light and features an aerosol chemistry experimental station, the researchers found new chemical compounds forming within one hour after the start of the reaction.

"The tunable VUV light of Beamline 9.0.2's custom-built VUV aerosol mass spectrometer minimized the fragmentation of organic molecules and enabled us to chemically characterize the secondhand smoke and identify individual constituents of secondary organic aerosols," says Sleiman. "The identification of multifunctional compounds, such as carbonyls and amines, present in the ultrafine particles, made it possible for us to estimate the Asthma Hazard Index for these compounds."

This study supports recommendations from the California EPA and the Air Resources Board that discourage the use of ozone-generating "air purifiers" that have been used to remove tobacco odors. However, the Berkeley Lab researchers caution that the levels of both ozone and nicotine in their study were at the high end of typical indoor conditions.

Says Sleiman, "We need to do further investigations to verify that the formation of ultrafine particles occurs under a range of real world conditions. However, given the high levels of nicotine measured indoors when smoking takes place regularly and the significant yield of ultrafine particles formation in our study, our findings suggest a new link between asthma and exposure to secondhand and thirdhand smoke."

—Lynn Yarris

 

For more information, contact:

  • Hugo Destaillats
  • (510) 486-5897

Additional information:

Berkeley Lab's Indoor Environment Department and its researchers.

Chemical Dynamics Beamline at the Advanced Light Source.

The Advanced Light Source at LBNL.

For more information on the University of California's Tobacco-Related Disease Research Program (TRDRP) visit the website or contact Kamlesh Asotra at or (510) 287-3366.

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