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09-08-2011 | General practice | Article

Air cleaners fail to prevent exposure to secondhand smoke


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MedWire News: High-efficiency air cleaners do not fully reduce the effects of second-hand smoke, say US researchers.

Arlene Butz (Johns Hopkins University, Baltimore, Maryland) and colleagues found that the use of a high-efficiency air cleaner did not reduce air nicotine levels and failed to counter the adverse effects of second-hand smoke, despite reducing indoor particulate matter (PM) and lowering the rate of daytime asthma symptoms.

The data, from a study of asthmatic children living with smokers, show that the reduced indoor PM levels are still not sufficient to meet standards for air quality, state the researchers in the Archives of Pediatric and Adolescent Medicine journal.

Despite warnings about the risks, 40-67% of inner-city children with asthma in the USA live with a smoker, writes the team. While total home smoking bans are the ideal, implementing such bans is difficult, especially in multi-unit housing complexes where other families might also smoke.

Past studies have shown that air cleaners can reduce air nicotine levels. Therefore, Butz and colleagues conducted a randomized controlled study to determine if an air cleaner, along with educational interventions promoting smoking bans, could reduce indoor air pollution levels.

In total, 115 children with asthma, who were residing with a smoker, were included in the study. The children assigned to the air cleaner treatment arm received a high-efficiency particle air (HEPA) cleaner in the home and bedroom.

Compared with homes that did not receive a HEPA cleaner (control group), those receiving an air cleaner and an air cleaner plus education had significantly lower fine and coarse PM levels after 6 months.

Mean PM2.5 concentrations declined by 19.9 µg/m3 and 16.1 µg/m3 in the air cleaner and air cleaner plus education group, respectively.

Despite these reductions, however, the PM concentrations still exceeded the Environmental Protection Agency's 24-hour daily standards for outdoor air quality.

Moreover, they exceeded levels observed in smoke-free homes.

In addition, the air cleaner failed to reduce measurements of air nicotine or urine cotinine concentrations.

On a more positive note, families who received the HEPA filter reported an increased in the number of days free from asthma symptoms when compared with controls; 1.36 symptom-free days more every 2 weeks, or approximately 33 days per year.

By MedWire Reporters

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