Effect of passive smoking, asthma, and respiratory infection on lung function in Australian children

Lung physiology and controlled exposure study design

Controlled human inhalation exposure ( CHIE) studies provide a unique opportunity to conduct formal experiments to examine the human health effects of airborne pollutants. Lung function, easily measured using spirometry, is a common physiological variable often utilized in these studies. By design, CHIE studies only induce mild and reversible acute effects, which may or may not predict adverse effects that may develop under chronic exposure conditions. There is substantial inter- and intra-individual variability in functional capacity and symptoms such as chest tightness and dyspnea, which are complex variables that are affected by individual perception, physiological lung impairment, and other variables (e.g., concomitant health conditions, and level of conditioning/fitness). Thus, the design of the CHIE study and physiological and environmental factors of study participants can affect each CHIE study's results. Researchers can address many of these critical issues in the problem formulation phase of CHIE studies, utilizing existing information on the expected effects of the substance of interest and possible modes of action. Thoughtful design and interpretation of CHIE studies will increase their utility for evaluating and setting environmental health policy.

Effects of second-hand smoking on lung functions in athlete and non-athlete school-aged children - observational study

Background

Second-hand smoking or environmental tobacco smoke is a critical health risk. Children are the most vulnerable to second-hand smoking because of their small bronchial ducts, less developed immunity, and low-physical activity.

Objectives

The purpose of this study was to ascertain the effects of second-hand smoking on lung functions in athlete and non-athlete school-aged children.

Methods

This observational study included forty-six school-aged children, their age was 8–15 years, assigned to three groups; 2 study groups and 1 control group (n=15). The study groups comprised of 16 football players, and of 15 cyclists. Lung functions were evaluated recording forced vital capacity, forced expiratory volume in 1 sec and peak expiratory flow using digital spirometer.

Results

All measures were recorded in definite values and the children were also classified into second-hand smoking (SH), or non-exposed to tobacco smoking (NE). The findings presented a significant increase (p<0.05) of the study groups in forced vital capacity, forced expiratory volume in 1 sec and peak expiratory flow solely for the non-exposed children. However, there were non-significant differences between the cyclists and football players or between the passive smoking children and non-exposed children in any of the two study groups (p>0.05).

Conclusion

The outcomes of this study suggest beneficial influences of the sports activity on the lung functions, without different influences of the cyclists and football players on the lung functions.

Pulmonary effects of active smoking and secondhand smoke exposure among adolescent students in Juárez, Mexico

BACKGROUND

Youth smoking trends among Latin American countries, including Mexico, are on the rise. Notably, although the high prevalence of smoking in teens has been well documented in the literature, few studies have evaluated the impact of smoking and secondhand smoke (SHS) exposure on their respiratory system.

OBJECTIVE

To investigate the effects of smoking and SHS exposure on the respiratory health and lung function among eighth-grade students in Juárez, Mexico.

METHODS

A cross-sectional study was undertaken on a sample of convenience. The study outcomes centered on evaluating 300 students' lung function by spirometry (forced expiratory volume in 1 second [FEV1], forced expiratory volume in 1 second/forced vital capacity ratio [FEV1/FVC], and forced mid-expiratory flow rate [FEF25%-75%]) and their respiratory health (smoking behavior and SHS exposure) by their self-reported responses to a standardized respiratory questionnaire. The study outcomes were compared among three distinct groups: 1) nonsmokers/nonexposed to SHS; 2) nonsmokers/exposed to SHS; and 3) smokers.

RESULTS

The majority of the study participants were 14 years old (85%), females (54%), who attended eighth grade in a public school setting (56%). Approximately, half reported being of low socioeconomic status (49%) and nonsmokers/exposed to SHS (49%). The lung function parameters of smokers were found to be lower (FEV1 =62.88±10.25; FEV1/FVC =83.50±14.15; and FEF25%-75% =66.35±12.55) than those recorded for the nonsmokers/exposed to SHS (FEV1 =69.41±11.35; FEV1/FVC =88.75±15.75; and FEF25%-75% =78.90±14.65) and significantly reduced when compared to the nonsmokers/nonexposed to SHS (FEV1 =79.14±13.61; FEV1/FVC =94.88±21.88; and FEF25%-75% =87.36±17.02) (P<0.001). Similarly, respiratory complaints were more prevalent among smokers and those exposed to SHS when compared to nonsmokers/nonexposed to SHS.

CONCLUSION

Our findings suggest that initiation of cigarette smoking and, to a lesser extent, exposure to SHS in adolescence leads to increased respiratory symptoms and reduction of pulmonary function test values. Public health initiatives that aim to prevent smoking initiation, assist in cessation, and lessen SHS exposure of adolescents need to be school-based and employed as early as middle school.

Detrimental effects of tobacco smoke exposure during development on postnatal lung function and asthma

Exposure to environmental tobacco smoke (ETS) during fetal development and early postnatal life is perhaps the most ubiquitous and hazardous of children's environmental exposures. The developing lung is highly susceptible to ETS. A large body of literature links both prenatal maternal smoking and children's ETS exposure to decreased lung growth. This review summarizes the state of the knowledge, including both human epidemiology and laboratory animal experiments, linking ETS, lung development, and respiratory outcomes. Important issues discussed include lung development and lung function and asthma in relation to ETS exposure during critical windows of growth. Prenatal exposure to ETS is associated with impaired lung function and increased risk of developing asthma, whereas postnatal exposure mainly acts to trigger respiratory symptoms and asthma attacks, but it also plays an important role in the occurrence of asthma in children. This review provides evidence that avoidance of ETS exposure both before and after birth is beneficial to long-term respiratory health, because airway function in later life is believed to be largely determined by lung development occurring in utero and in early infancy.

Effects of passive smoking on lung function in children

BACKGROUND

Passive smoking can have significant effects on lung function with reductions in forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and forced mid-expiratory flow rate (FEF25-75%) of between 5 and 10%.

METHODS

Fifty non-smoking children aged 6-15 years, who had no history of asthma or atopy and no parental history of atopy, were assessed with respect to their lung functions (FEV1, FEV1/FVC, FEF25-75%).

RESULTS

Thirty-three of these children were being exposed to environmental tobacco smoke inside their homes, while 17 children were not exposed. In the 'passive smoker' group the FEV1, FEV1/FVC and FEF25-75% values were found to be significantly lower than the non-smoker control group's values (P = 0.0080, 0.0228 and 0.0003, respectively). The decrease in FEF25-75% was significantly correlated inversely with the number of cigarettes smoked per day (P = 0.0261).

CONCLUSION

There is sufficient evidence to support the notion that environmental tobacco smoke is a serious health burden for children. Considering that recent studies suggest that up to 70% of children grow up in homes with at least one smoker, every effort should be made to reduce these children's exposure to environmental tobacco smoke and to give them a chance to grow up in a more healthy environment.

Impact of respiratory illness on expiratory flow rates in normal, asthmatic, and allergic children

We examined the effects of current respiratory illness (RI) on pulmonary function (PF) in 1,103 subjects who underwent spirometry at schools twice within a 4-month period. Before spirometry, subjects were asked if they had a "cold or other chest illness" during the previous month, and if so, whether they had fully recovered. Those who had not recovered were considered to have an RI. We found that children without RI at their first PF test who reported RI on retest had significantly lower forced expiratory volume in 1 sec (FEV(1)) (-0.8%), peak expiratory flow rate (PEFR) (-2.2%), forced expiratory flow between 25-75% of vital capacity (FEF(25-75)) (-3.5%), and forced expiratory flow at 75% of vital capacity (FEF(75)) (-5.1%) than those without RI on both test and retest. Restriction of subjects to those without a history of doctor-diagnosed asthma did not appreciably change these findings. Children with hay fever had significantly larger RI-associated decreases for FEV(1), FEF(25-75), and FEF(75), but not PEFR, than those without hay fever. Among asthmatic subjects, those with active asthma had larger RI-associated decreases in FEF(25-75) and FEF(75), but not PEFR, than those without asthma. There was limited evidence that small airway losses were greater in children less than 12.5 years old. We conclude that RI in children who are well enough to attend school may reduce expiratory flow rates. These effects are greater for children with active asthma or hay fever than in those without, and may be inversely related to age.

Spirometric reference values in Estonian schoolchildren

This study was conducted to describe the relationship between anthropometric parameters and lung function in Estonian children, to determine the reference values for spirometry, and to compare these results with other data sets. The results are based on 1170 healthy non-smoking children (643 girls and 527 boys), aged 6-18 years. The spiroanalyser Pneumoscreen II (Jaeger) was used to register dynamic lung parameters. Natural logarithmic values of lung volumes, standing or sitting height and age were used in the final regression model. Prediction equations for forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), peak expiratory flow, forced expiratory flows when 50 and 75% of FVC has been exhaled, and mean forced expiratory flow over the middle 50% of the FVC for both sexes are presented. In comparison with recent data from European children the reference values were close for FVC, the differences were bigger for FEV1 and forced expiratory flows, especially in taller children.

Airway responsiveness in early infancy predicts asthma, lung function, and respiratory symptoms by school age

Asthma is the most common chronic childhood disease in developed nations. Little is known about the relationship between airway responsiveness in infancy and the development of asthma later in life. The relationship of airway responsiveness at 1 mo with asthma, atopy, lower respiratory symptoms, and lung function at 6 yr of age was investigated prospectively in 95 white children from a randomly ascertained birth cohort. Baseline spirometry, airway responsiveness to histamine, and skin reactivity to common allergens were assessed at the age of 1 mo and 6 yr. Total serum immunoglobulin E (IgE) was measured from cord blood and at 6 yr. Blood eosinophil counts were measured at 6 yr only. Family, symptom, and exposure histories at both time points were derived from questionnaire data. Independently of the other factors assessed, increased airway responsiveness at 1 mo was significantly associated with the following parameters measured at six yr: decreased FEV(1) (p < 0.001); decreased FVC (p < 0.001); physician-diagnosed asthma (p < 0.001); and lower respiratory tract symptoms (p < 0.05). None of the other physiologic factors measured in infancy showed such consistent associations with important clinical and physiologic outcomes at age 6. These data suggest that airway responsiveness in early life defines a functional state that is associated with abnormal airway function, lower respiratory symptoms, and the emergence of asthma by 6 yr of age.

Effects of in utero and environmental tobacco smoke exposure on lung function in boys and girls with and without asthma

To investigate whether the effects of in utero exposure to maternal smoking and environmental tobacco smoke (ETS) exposure on lung function vary by sex or asthma status, we examined medical history and tobacco smoke exposure data for 5,263 participants in the Children's Health Study. At study enrollment, parents or guardians of each subject completed a questionnaire, and lung function was measured spirometrically with maximum forced expiratory flow-volume maneuvers. To assess the in utero effects of maternal smoking and ETS exposure on lung function, we used regression splines that accounted for the nonlinear relationship between pulmonary function, height, and age. In utero exposure to maternal smoking was independently associated with deficits in lung function that were larger for children with asthma. Boys and girls with a history of in utero exposure to maternal smoking showed deficits in maximum midexpiratory flow (MMEF) and a decrease in the FEV(1)/FVC ratio. As compared with children without asthma, boys with asthma had significantly larger deficits from in utero exposure in FVC, MMEF, and FEV(1)/FVC, and girls with asthma had larger decreases in FEV(1)/FVC. The effect of ETS exposure varied by children's gender and asthma status. Deficits in flows associated with current ETS exposure were present in children with and without asthma but were significant only among children without asthma. Past ETS exposure was associated with reduced FEV(1), MMEF, and FEV(1)/FVC among boys with asthma. In contrast, past ETS exposure was associated with decreased flow rates in girls without asthma. In summary, both in utero exposure to maternal smoking and ETS exposure were associated with persistent deficits in lung function. The effects of in utero exposure were greatest among children with asthma.

Respiratory effects of environmental tobacco smoke in a panel study of asthmatic and symptomatic children

The effect of environmental tobacco smoke (ETS) on respiratory health was investigated among 7- to 12-yr-old children with asthmatic (n = 74) or cough (n = 95) symptoms. For 3 mo the children measured their peak expiratory flow rate (PEFR) every morning and evening, and kept a daily diary of respiratory symptoms. They also noted daily whether they had used respiratory medication and whether someone had smoked inside their home. Eleven percent of the asthmatic children and 14% of the children with cough had exposure to ETS at home during the study. In multiple regression and analyses controlling for potential confounders, any exposure to ETS during the study was associated with a reduction of 42 L/min (95% confidence interval [CI]: 10 to 74 L/min) in morning and 41 L/min (95% CI: 8 to 74 L/min) in evening PEFR among asthmatic children. Among these children, a dose-dependent increase in the effect of ETS was also seen. Daily variation in ETS exposure was only weakly (-9.2 L/min; 95% CI: 2.9 to 21.2 L/min) associated with PEFR, but the previous day's ETS exposure was a risk factor for bronchodilator use (relative risk [RR]: 10.3; 95% CI: 1.3 to 83.7), as well as for cough (RR: 12.4; 95% CI: 2.4 to 63.3) and phlegm production (RR: 7. 8; 95% CI: 1.4 to 41.7), on any given day. Among children with cough only, there was only a weak suggestion of any possible ETS effect. In conclusion, we found that exposure to ETS was associated with a decline in peak flow and increases in respiratory symptoms and use of bronchodilator drugs among asthmatic children.

Smoking and pediatric respiratory health

Many children are exposed to smoking both prenatally and postnatally. Prenatal exposure to mainstream smoke from the mother and even to environmental tobacco smoke (ETS) from the mother in utero has been shown to change fetal lung development and cause airflow obstruction and airway hyperresponsiveness. Children exposed to ETS postnatally have more symptoms of cough, wheeze, respiratory illnesses, decreases in lung function, and increases in airway responsiveness. Smoke exposure is associated with the early development of asthma, increased severity of asthma, and the development of allergy. Finally smoke exposure is associated with sudden infant death and airway obstruction. This article reviews the spectrum of effects of cigarette smoke exposure on the respiratory health of infants and children and highlights basic science research exploring the mechanisms of these effects.

[Effects of environmental tobacco smoke on lower respiratory system of children under 5 years of age]

OBJECTIVE

To determine the effects of second-hand smoke in the respiratory system of children under 5 years old.

METHODS

A cross sectional study of a total of 1,104 children under 5 years old. Information about respiratory symptoms and illness, family history of respiratory diseases, smoking habits of household members and housing conditions were assessed by home interviews with the children's parents.

RESULTS

We studied 546 boys and 558 girls. Among 611 children exposed to second-hand smoke, 82% had respiratory problems (odds ratio = 1.64; 95% confidence interval: 1.21-2.20). Children whose parents were smokers at the time of the survey were more likely to experience wheezing than children of nonsmoking parents (odds ratio = 1.66; 95% confidence interval: 1.21-2.27), shortness of breath (odds ratio = 1.91; 95% confidence interval: 1. 36-2.67), morning and day time or night coughs (odds ratio = 1.58; 95% confidence interval: 1.09-2.28). The odds ratio for asthma, bronchitis and pneumonia was greater for children exposed to second-hand smoke (odds ratio = 1.60; 95% confidence interval: 1. 11-2.31).

CONCLUSIONS

Maternal smoking, paternal smoking, family history of respiratory diseases, and housing conditions are considered risk factors for respiratory diseases in children.

Health effects of passive smoking. 9. Parental smoking and spirometric indices in children

BACKGROUND

A systematic quantitative review was conducted of the evidence relating parental smoking to spirometric indices in children.

METHODS

An electronic search of the Embase and Medline databases was completed in April 1997 and identified 692 articles from which we included four studies in neonates, 42 cross-sectional studies in school aged children (22 were included in a meta-analysis), and six longitudinal studies of lung function development.

RESULTS

In a pooled analyses of 21 surveys of school aged children the percentage reduction in forced expiratory volume in one second (FEV1) in children exposed to parental smoking compared with those not exposed was 1.4% (95% CI 1.0 to 1.9). Effects were greater on mid expiratory flow rates (5.0% reduction, 95% CI 3.3 to 6.6) and end expiratory flow rates (4.3% reduction, 95% CI 3.1 to 5.5). Adjustment for potential confounding variables had little effect on the estimates. A number of studies reported clear evidence of exposure response. Where exposure was explicitly identified it was usually maternal smoking. Two studies in neonates have reported effects of prenatal exposure to maternal smoking. Of five cross sectional studies that compared effects of perinatal exposure (retrospectively assessed) with current exposure to maternal smoking in later childhood, the three largest concluded that the major effect was in utero or neonatal exposure. Longitudinal studies suggest a small effect of current exposure on growth in lung function, but with some heterogeneity between studies.

CONCLUSIONS

Maternal smoking is associated with small but statistically significant deficits in FEV1 and other spirometric indices in school aged children. This is almost certainly a causal relationship. Much of the effect may be due to maternal smoking during pregnancy.

Parental smoking, bronchial reactivity and peak flow variability in children

BACKGROUND

A systematic quantitative review was conducted of the evidence relating environmental tobacco smoke to bronchial hyperresponsiveness (BHR) during childhood.

METHODS

Twenty-nine relevant studies were identified after consideration of 1593 articles selected by electronic search of the Embase and Medline databases using keywords relevant to passive smoking in children. The search was completed in April 1997.

RESULTS

Of 19 studies using challenge tests in children of school age, 10 (5759 children) could be summarised as the odds ratio of being bronchial hyperreactive in children exposed to environmental tobacco smoke compared with those not exposed. The pooled odds ratio for maternal smoking was 1.29 (95% confidence limits 1.10 to 1.50) with no evidence of heterogeneity between studies. However, in five further studies of 3531 children providing some evidence, but not odds ratios, none were statistically significant. A further four studies on 5233 children have collected data but are not published. In contrast, all four studies of circadian variation in peak expiratory flow found increased variation in children exposed to environmental tobacco smoke.

CONCLUSIONS

A clear effect of exposure to environmental tobacco smoke on BHR in the general population has not been established. While the meta-analysis suggests a small but real increase in BHR in school aged children, it seems likely that this estimate is biased upwards due to publication bias. In contrast, limited evidence suggests greater variation in peak expiratory flow in children of smoking parents.