Intended for healthcare professionals


Effect of counselling mothers on their children's exposure to environmental tobacco smoke: randomised controlled trial

BMJ 2000; 321 doi: (Published 05 August 2000) Cite this as: BMJ 2000;321:337
  1. Melbourne F Hovell (behepi{at}, professora,
  2. Joy M Zakarian, senior research associatea,
  3. Georg E Matt, professora,
  4. C Richard Hofstetter, professora,
  5. J Thomas Bernert, supervisory research chemistb,
  6. James Pirkle, assistant director for scienceb
  1. a Center for Behavioral Epidemiology and Community Health (C-BEACH), Graduate School of Public Health, San Diego State University, San Diego, CA 92182, USA
  2. b Centers for Disease Control and Prevention, National Center for Environmental Health, Division of Laboratory Sciences, Atlanta, GA 30341-3724, USA
  1. Correspondence to: M F Hovell
  • Accepted 3 August 2000


Objective: To test the efficacy of behavioural counselling for smoking mothers in reducing young children's exposure to environmental tobacco smoke.

Design: Randomised double blind controlled trial.

Setting: Low income homes in San Diego county, California.

Participants: 108 ethnically diverse mothers who exposed their children (aged <4 years) to tobacco smoke in the home.

Intervention: Mothers were given seven counselling sessions over three months.

Main outcome measures: Children's reported exposure to environmental tobacco smoke from mothers in the home and from all sources; children's cotinine concentrations in urine.

Results: Mothers' reports of children's exposure to their smoke in the home declined in the counselled group from 27.30 cigarettes/week at baseline, to 4.47 at three months, to 3.66 at 12 months and in the controls from 24.56, to 12.08, to 8.38. The differences between the groups by time were significant (P=0.002). Reported exposure to smoke from all sources showed similar declines, with significant differences between groups by time (P=0.008). At 12 months, the reported exposure in the counselled group was 41.2% that of controls for mothers' smoke (95% confidence interval 34.2% to 48.3%) and was 45.7% (38.4% to 53.0%) that of controls for all sources of smoke. Children's mean urine cotinine concentrations decreased slightly in the counselled group from 10.93 ng/ml at baseline to 10.47 ng/ml at 12 months but increased in the controls from 9.43 ng/ml to 17.47 ng/ml (differences between groups by time P=0.008). At 12 months the cotinine concentration in the counselled group was 55.6% (48.2% to 63.0%) that of controls.

Conclusions: Counselling was effective in reducing children's exposure to environmental tobacco smoke. Similar counselling in medical and social services might protect millions of children from environmental tobacco smoke in their homes.


  • Funding This research was supported by Grant No 027946 SFP awarded to MFH from the Robert Wood Johnson Foundation Smoke-Free Families Program, and by discretionary funds from the Center for Behavioral Epidemiology and Community Health.

  • Competing interests None declared.

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