Another reason for including asthma on the list of potential health risks posed by secondhand tobacco smoke, especially for non-smokers, has been uncovered. Furthermore, the practice of using ozone to remove the smell of tobacco smoke from indoor environments, including hotel rooms and the interiors of vehicles, is probably a bad idea.
A new study by researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab) 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.
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, a study, also 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. Until now, however, in terms of forming ultrafine particles, there have been no studies on 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 that is released back to indoor air for a period of months after smoking ceased. Ozone is a common urban pollutant that infiltrates from outdoor air through ventilation that has been linked to health problems, including asthma and respiratory ailments.
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."
While the findings in this study support recommendations from the California EPA and the Air Resources Board that discourage the use of ozone-generating "air purifiers," which among other applications, have been used for the removal of tobacco odors, 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, "In addition, 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 new link between asthma and exposure to secondhand and thirdhand smoke."
Secondary organic aerosol formation from ozone-initiated reactions with nicotine and secondhand tobacco smoke.
Mohamad Sleiman, Hugo Destaillats, Jared D. Smith, Chen-Lin Liu, Musahid Ahmed, Kevin R. Wilson and Lara A. Gundel
Atmospheric Environment, 2010; DOI: 10.1016/j.atmosenv.2010.07.023
Link to Atmospheric Environ abstract