The Tayside infant morbidity and mortality study: effect on health of using gas for cooking

SmokeHaz: Systematic Reviews and Meta-analyses of the Effects of Smoking on Respiratory Health

BACKGROUND

Smoking tobacco increases the risk of respiratory disease in adults and children, but communicating the magnitude of these effects in a scientific manner that is accessible and usable by the public and policymakers presents a challenge. We have therefore summarized scientific data on the impact of smoking on respiratory diseases to provide the content for a unique resource, SmokeHaz.

METHODS

We conducted systematic reviews and meta-analyses of longitudinal studies (published to 2013) identified from electronic databases, gray literature, and experts. Random effect meta-analyses were used to pool the findings.

RESULTS

We included 216 articles. Among adult smokers, we confirmed substantially increased risks of lung cancer (risk ratio (RR), 10.92; 95% CI, 8.28-14.40; 34 studies), COPD (RR, 4.01; 95% CI, 3.18-5.05; 22 studies), and asthma (RR, 1.61; 95% CI, 1.07-2.42; eight studies). Exposure to passive smoke significantly increased the risk of lung cancer in adult nonsmokers and increased the risks of asthma, wheeze, lower respiratory infections, and reduced lung function in children. Smoking significantly increased the risk of sleep apnea and asthma exacerbations in adult and pregnant populations, and active and passive smoking increased the risk of tuberculosis.

CONCLUSIONS

These findings have been translated into easily digestible content and published on the SmokeHaz website.

Parental and household smoking and the increased risk of bronchitis, bronchiolitis and other lower respiratory infections in infancy: systematic review and meta-analysis

BACKGROUND

Passive smoke exposure increases the risk of lower respiratory infection (LRI) in infants, but the extensive literature on this association has not been systematically reviewed for nearly ten years. The aim of this paper is to provide an updated systematic review and meta-analysis of studies of the association between passive smoking and LRI, and with diagnostic subcategories including bronchiolitis, in infants aged two years and under.

METHODS

We searched MEDLINE and EMBASE (to November 2010), reference lists from publications and abstracts from major conference proceedings to identify all relevant publications. Random effect pooled odds ratios (OR) with 95% confidence intervals (CI) were estimated.

RESULTS

We identified 60 studies suitable for inclusion in the meta-analysis. Smoking by either parent or other household members significantly increased the risk of LRI; odds ratios (OR) were 1.22 (95% CI 1.10 to 1.35) for paternal smoking, 1.62 (95% CI 1.38 to 1.89) if both parents smoked, and 1.54 (95% CI 1.40 to 1.69) for any household member smoking. Pre-natal maternal smoking (OR 1.24, 95% CI 1.11 to 1.38) had a weaker effect than post-natal smoking (OR 1.58, 95% CI 1.45 to 1.73). The strongest effect was on bronchiolitis, where the risk of any household smoking was increased by an OR of 2.51 (95% CI 1.96 to 3.21).

CONCLUSIONS

Passive smoking in the family home is a major influence on the risk of LRI in infants, and especially on bronchiolitis. Risk is particularly strong in relation to post-natal maternal smoking. Strategies to prevent passive smoke exposure in young children are an urgent public and child health priority.

Exposure to NO2 and nitrous acid and respiratory symptoms in the first year of life

BACKGROUND

Effects of nitrogen dioxide (NO2) on respiratory health have been the subject of extensive research. The outcomes of these studies were not consistent. Exposure to nitrous acid, which is a primary product of combustion, and is also formed when NO2 reacts with water, may play an important role in respiratory health. We estimate the independent effects of exposure to nitrogen dioxide and nitrous acid on respiratory symptoms during the first year of life.

METHODS

Nitrogen dioxide and nitrous acid concentrations were measured once (1996-1998) in the homes of 768 infants who were at risk for developing asthma. Infants were living in southern New England. The frequency of respiratory symptoms in these children was recorded during the first year of life.

RESULTS

Infants living in homes with an NO2 concentration exceeding 17.4 ppb (highest quartile) had a higher frequency of days with wheeze (rate ratio = 2.2; 95% confidence interval = 1.4-3.4), persistent cough (1.8; 1.2-2.7), and shortness of breath (3.1; 1.8-5.6) when compared with infants in homes that had NO2 concentrations lower than 5.1 ppb (lowest quartile), controlling for nitrous acid concentration. Nitrous acid exposure was not independently associated with respiratory symptoms.

CONCLUSIONS

Among infants at risk for developing asthma, the frequency of reported respiratory symptoms in the first year of life was associated with levels of NO2 not currently considered to be harmful.

Assessment of personal and community-level exposures to particulate matter among children with asthma in Detroit, Michigan, as part of Community Action Against Asthma (CAAA)

We report on the research conducted by the Community Action Against Asthma (CAAA) in Detroit, Michigan, to evaluate personal and community-level exposures to particulate matter (PM) among children with asthma living in an urban environment. CAAA is a community-based participatory research collaboration among academia, health agencies, and community-based organizations. CAAA investigates the effects of environmental exposures on the residents of Detroit through a participatory process that engages participants from the affected communities in all aspects of the design and conduct of the research; disseminates the results to all parties involved; and uses the research results to design, in collaboration with all partners, interventions to reduce the identified environmental exposures. The CAAA PM exposure assessment includes four seasonal measurement campaigns each year that are conducted for a 2-week duration each season. In each seasonal measurement period, daily ambient measurements of PM2.5 and PM10 (particulate matter with a mass median aerodynamic diameter less than 2.5 microm and 10 microm, respectively) are collected at two elementary schools in the eastside and southwest communities of Detroit. Concurrently, indoor measurements of PM2.5 and PM10 are made at the schools as well as inside the homes of a subset of 20 children with asthma. Daily personal exposure measurements of PM10 are also collected for these 20 children with asthma. Results from the first five seasonal assessment periods reveal that mean personal PM10 (68.4 39.2 microg/m(3)) and indoor home PM10 (52.2 30.6 microg/m(3)) exposures are significantly greater (p < 0.05) than the outdoor PM10 concentrations (25.8 11.8 microg/m(3)). The same was also found for PM2.5 (indoor PM2.5 = 34.4 21.7 microg/m(3); outdoor PM2.5 = 15.6 8.2 microg/m(3)). In addition, significant differences (p < 0.05) in community-level exposure to both PM10 and PM2.5 are observed between the two Detroit communities (southwest PM10 = 28.9 14.4 microg/m(3)), PM2.5 = 17.0 9.3 microg/m(3); eastside PM10 = 23.8 12.1 microg/m(3), PM2.5 = 15.5 9.0 microg/m(3). The increased levels in the southwest Detroit community are likely due to the proximity to heavy industrial pollutant point sources and interstate motorways. Trace element characterization of filter samples collected over the 2-year period will allow a more complete assessment of the PM components. When combined with other project measures, including concurrent seasonal twice-daily peak expiratory flow and forced expiratory volume at 1 sec and daily asthma symptom and medication dairies for 300 children with asthma living in the two Detroit communities, these data will allow not only investigations into the sources of PM in the Detroit airshed with regard to PM exposure assessment but also the role of air pollutants in exacerbation of childhood asthma.

Nitrogen dioxide exposure from domestic gas cooking and airway response in asthmatic women

BACKGROUND

Previous studies have not found a consistent association between exposure to domestic cooking using gas appliances and exacerbation of asthma. We investigated the immediate airflow response to acute exposure from single episodes of gas cooking, and peak airflow variability from continued exposure to repeated episodes of gas cooking in a group of non-smoking asthmatic women.

METHODS

Sixteen adult non-smoking women with mild to severe persistent asthma were studied. The acute short term level of nitrogen dioxide (NO2) during gas cooking episodes and the mean exposure to NO2 from repeated gas cooking episodes were measured over a 2 week period, as well as proxy measures of frequency of cooking on each day and the length of time spent cooking each day. Their asthma status was monitored using peak expiratory flow rates (PEFR) before and after cooking, 2 week self-recorded serial readings of PEFR, respiratory symptom severity score, and use of rescue bronchodilators for acute asthma attacks.

RESULTS

Cooking was significantly associated with an immediate mean fall in PEFR of 3.4% (p=0.015, paired t test). The acute short term NO2 level during cooking was significantly correlated with the fall in PEFR (r=–0.579; p=0.019). The frequency of cooking over a 2 week period was positively correlated with the mean exposure to NO2(r=0.529; p=0.042). Continued exposure to NO2 over a 2 week period was associated significantly with increased frequency of rescue bronchodilator usage for asthma attacks (r=0.597; p=0.031). However, it was negatively associated with PEFR variability (r=–0.512; p=0.051) and respiratory symptom severity score (r= –0.567; p=0.043), probably due to the masking effects of bronchodilator treatment.

CONCLUSIONS

Acute short term exposure to NO2 from single episodes of gas cooking is associated with immediate airflow limitation. Continued exposure from repeated episodes of gas cooking in asthmatic women is associated with greater use of rescue bronchodilators.

Nitrogen dioxide exposure from domestic gas cooking and airway response in asthmatic women

BACKGROUND

Previous studies have not found a consistent association between exposure to domestic cooking using gas appliances and exacerbation of asthma. We investigated the immediate airflow response to acute exposure from single episodes of gas cooking, and peak airflow variability from continued exposure to repeated episodes of gas cooking in a group of non-smoking asthmatic women.

METHODS

Sixteen adult non-smoking women with mild to severe persistent asthma were studied. The acute short term level of nitrogen dioxide (NO2) during gas cooking episodes and the mean exposure to NO2 from repeated gas cooking episodes were measured over a 2 week period, as well as proxy measures of frequency of cooking on each day and the length of time spent cooking each day. Their asthma status was monitored using peak expiratory flow rates (PEFR) before and after cooking, 2 week self-recorded serial readings of PEFR, respiratory symptom severity score, and use of rescue bronchodilators for acute asthma attacks.

RESULTS

Cooking was significantly associated with an immediate mean fall in PEFR of 3.4% (p=0.015, paired t test). The acute short term NO2 level during cooking was significantly correlated with the fall in PEFR (r=-0.579; p=0.019). The frequency of cooking over a 2 week period was positively correlated with the mean exposure to NO2 (r=0.529; p=0.042). Continued exposure to NO2 over a 2 week period was associated significantly with increased frequency of rescue bronchodilator usage for asthma attacks (r=0.597; p=0.031). However, it was negatively associated with PEFR variability (r=-0.512; p=0.051) and respiratory symptom severity score (r= -0.567; p=0.043), probably due to the masking effects of bronchodilator treatment.

CONCLUSIONS

Acute short term exposure to NO2 from single episodes of gas cooking is associated with immediate airflow limitation. Continued exposure from repeated episodes of gas cooking in asthmatic women is associated with greater use of rescue bronchodilators.

Nitrogen dioxide exposure assessment and cough among preschool children

The association between exposure to ambient air nitrogen dioxide and cough was evaluated in a panel study among 162 children aged 3-6 y. The weekly average nitrogen dioxide exposure was assessed with Palmes-tube measurements in three ways: (1) personally, (2) outside day-care centers, and (3) inside day-care centers. Ambient air nitrogen dioxide concentrations were obtained from the local network that monitored air quality. The parents recorded cough episodes daily in a diary. The risk of cough increased significantly (relative risk = 3.63; 95% confidence interval = 1.41, 9.30) in the highest personal nitrogen dioxide exposure category in winter, and a nonsignificant positive trend was noted for the other assessment groups. In spring, risk increased nonsignificantly in all exposure-assessment groups, except for the fixed-site monitoring assessment. It is important that investigators select an exposure-assessment method sufficiently accurate to reflect the effective pollutant dose in subjects.

[Epidemiology of respiratory allergy in children]

Epidemiology of paediatric respiratory allergic disorders allows the approach to causal and preventive risk factors by studying groups or sub groups of children in different locations and under different conditions. This is, however, complicated by the lack of consensus on disease definitions, which renders comparisons between studies difficult. Atopy is usually defined by the presence of positive skin tests (wheal size of at least a mean diameter > or = 3 mm), by the presence of specific IgE, or by the presence of increased total IgE (> or = 100 UI/mL). Infantile asthma is not well defined, complicated by the high prevalence of bronchiolitis; one thus questions between wheezing or wheezy bronchitis. Prevalence is high: among early wheezers, two populations will be defined by the medium term evolution: transient wheezers and persistent wheezers. Risk factors for these two conditions are different. Childhood asthma may be defined by the diagnosis of asthma (specific but fairly non-sensitive), by asthmatic symptoms (wheezing, waking by an attack of shortness of breath) (sensitive but not very specific), or by the combination of symptoms and airway hyperresponsiveness. The ISAAC study has standardised a questionnaire to assess the prevalence of asthma. The preliminary results show that there are wide variations across the world. The prevalence is low in Africa and Asia, intermediate in Europe, and high in Anglo-Saxon countries. The prevalence of asthma has gradually increased over the past 20 years in developed countries. Asthma and atopy are closely associated in children. Risk factors are genetic, associated with sex and environmental factors. Among these, allergic sensitisation is associated with the degree of exposure to allergens. Westernization of way of life is associated with increased prevalence of atopy, allergic rhinitis and asthma. Atopy seems inversely correlated to certain infections. Passive smoking is clearly associated with early wheezing. This and atmospheric pollution aggravate childhood asthma. However, the inducing role of pollution on asthma is still controversial.

Determinants of nitrogen dioxide concentrations in indoor ice skating rinks

OBJECTIVES

The combination of poor ventilation and fuel-powered ice resurfacers has resulted in elevated nitrogen dioxide (NO2) concentrations in many indoor ice skating rinks. This study examined the factors influencing concentrations and the effects of various engineering controls in ice rinks with different resurfacer fuels.

METHODS

Indoor NO2 concentrations were measured in 19 enclosed ice skating rinks over 3 winters by means of passive samplers, with 1-week average measurements during the first winter pilot study and single-day working-hour measurements in the final 2 winters. Personal exposures to drivers also were assessed during the last winter.

RESULTS

Rinks in which propane-fueled resurfacers were used had a daily mean indoor NO2 concentration of 206 ppb, compared with 132 ppb for gasoline-fueled and 37 ppb for electric-powered resurfacers. Engineering controls, such as increased ventilation and resurfacer tuning, reduced NO2 concentrations by 65% on average, but outcomes varied widely, and concentrations increased in subsequent months.

CONCLUSIONS

Electric ice resurfacers, increased ventilation, or emission control systems are recommended to protect the health of workers and patrons, with surveillance programs proposed to track implementation and maintain an observer effect.

Indoor environmental risk factors and childhood asthma: a case-control study in a subtropical area

This study examined the relation between indoor environmental factors and childhood asthma in a subtropical area. A hospital-based case-control study was performed in Kaohsiung, Taiwan, between July of 1995 and June of 1996. Eighty-six children seen in the out-patient clinic of our university hospital and who had a first-time diagnosis of asthma made by a pediatrician were the test group; 86 control subjects were selected from children attending the Childhood Orthopaedic Clinic in the same hospital and who had no previous diagnosis of asthma or asthma symptoms and no history of physician confirmed atopic diseases. The control subjects were matched with test case children on the basis of gender and age. Information was obtained from parents using a structured questionnaire. Of the many indoor environmental factors included in this study, only home dampness showed an association with asthma (adjusted odds ratio=1.77; 95% confidence intervals, 1.24-2.53). We conclude that dampness in the home is a new public health risk factor related to asthma in subtropical areas.

Childhood asthma and the indoor environment in a subtropical area

STUDY OBJECTIVES

The objective of this study is to examine the relationship between indoor environmental factors and childhood asthma in a subtropical area.

DESIGN

A case-control study was performed using participants of a prevalence survey that included 165 schoolchildren with asthma and 165 age- and gender-matched control subjects.

SETTING

The study was confined to 4,164 schoolchildren aged 6 to 12 years attending eight primary schools in Kaohsiung County rural municipalities who participated in a prevalence study concerning the health effects of the indoor environment.

PARTICIPANTS

Cases (n=165) were defined as children with current asthma confirmed by a physician. Control subjects (n=165) were selected from the same school and class and matched for age and gender, and they did not have a previous diagnosis of asthma, history of physician-confirmed atopic diseases, persistent wheezing, cough, or phlegm, or reported chest illness, pneumonia, or bronchitis.

MEASUREMENTS AND RESULTS

Information regarding the home environment was obtained using a structured written questionnaire, completed by the parents of the children. Of the many indoor environmental factors included in this study, only home dampness showed an association with asthma (odds ratio=2.65).

CONCLUSIONS

We conclude that dampness in the home is a new public health issue in subtropical areas.

Effects of indoor environmental factors on respiratory health of children in a subtropical climate

This study was conducted to determine whether indoor environmental factors affected respiratory symptoms in 4164 primary school children in Kaohsiung rural areas of Taiwan. Information on respiratory health symptoms and characteristics of the housing was obtained using a written questionnaire, completed by the parents of children. Multiple logistic regression analysis examined the relationship between respiratory health symptoms (cough, wheezing, bronchitis, asthma, and allergic rhinitis) and housing factors. Home dampness was significantly associated with all respiratory health symptoms. Incense burning and mosquito repellant burning showed effects on the reporting of coughing symptoms. No apparent associations were found with the other indoor factors included in this study or respiratory health symptoms. We conclude that dampness in the home has a pronounced effects on respiratory health symptoms and is a new public health issue in subtropical areas.

Front-door concentrations and personal exposures of Danish children to nitrogen dioxide

The aims of the study were to evaluate the front-door concentration of traffic exhaust fumes as a surrogate for the personal exposure of children and to study factors in the behavior and the environment of children that affect their personal exposure to nitrogen dioxide (NO(2)). The exposure to NO(2) of 103 children living in Copenhagen and 101 children living in rural areas of Denmark was studied by measuring average concentrations over 1 week with diffusive badge samplers placed outside the front door of the home, inside the child's bedroom, and on each child. Detailed information about the activities of the children involving potential exposure to NO(2) was noted in diaries. The results indicated that the front-door concentration of traffic pollution might be used to classify the personal exposure of urban children, although misclassification would be introduced. Multiple regression analysis showed several factors that affected the personal NO(2) exposure of the children independently, including the front-door concentration, the bedroom concentration, time spent outdoors, gas appliances used at home, passive smoking, and burning candles.

Damp housing conditions and respiratory symptoms in primary school children

There is evidence that indoor air pollution contributes to the development of respiratory symptoms. This study examined the relationships between dampness in houses and respiratory symptoms in 4,164 primary school children in the subtropical rural areas of the Kaohsiung region, Taiwan. Dampness in homes was assessed by questionnaires that reported 1) general dampness, 2) mold or mildew inside the home, or 3) flooding (appearance of standing water within the home, water damage, or leaks of water into the building). Evidence for upper and lower respiratory symptoms were also collected by questionnaires. Recorded symptoms included cough, wheezing, pneumonia, bronchitis, and asthma. Degrees of dampness were reported as 12.2%, 30.1%, and 43.4%, respectively by the parents or guardians of the study population. The prevalence of respiratory symptoms was consistently higher in homes with indications of dampness than in non-damp homes. After adjustments for potential confounders, selected respiratory symptoms among the childhood population were significantly higher in damp than non-damp homes, with the exception of pneumonia. We conclude that dampness in the home is a strong predictor of and risk factor for respiratory symptoms and constitutes a significant public health problem in subtropical area.

Association of respiratory symptoms and lung function in young adults with use of domestic gas appliances

BACKGROUND

There is evidence from some studies that people living in homes with gas stoves and other unvented gas appliances experience more respiratory symptoms than those who use other fuels for cooking and heating, but other studies have found no such association. We have investigated whether the use of gas appliances is associated with an increased risk of respiratory symptoms and whether sensitisation to common environmental allergens modifies any such association.

METHODS

A stratified random sample of 15,000 adults aged 20-44 years, living in three towns in East Anglia, UK, were sent a questionnaire on asthma and hayfever. From those who responded, a random sample of 1864 were invited to complete an extended questionnaire that included questions on use of gas appliances, to give blood samples for measurements of total IgE and specific IgE to common allergens, and to undergo tests of respiratory function, 659 women and 500 men agreed to an interview. The association of the use of gas appliances with respiratory symptoms, total IgE, specific IgE, and respiratory function was assessed by logistic and multiple regression models.

FINDINGS

Women who reported they mainly used gas for cooking had an increased risk of several asthma-like symptoms during the past 12 months including wheeze (odds ratio 2.07 [95% CI 1.41-3.05]), waking with shortness of breath (2.32 [1.25-4.34]), and asthma attacks (2.60 [1.20 -5.6]). Gas cooking increased the risk of symptoms more in women who were atopic than in non-atopic women but the difference did not reach significance (p . 0.05). Women who used a gas stove or had an open gas fire had reduced lung function (forced expiratory volume in 1 s [FEV1]) and increased airways obstruction (FEV1 as a percentage of forced vital capacity) compared with women who did not. These associations were not observed in men.

INTERPRETATION

In East Anglia, the use of gas cooking is significantly associated with subjective and objective markers of respiratory morbidity in women but not in men. Women may be more susceptible than men to the products of gas combustion or they may have greater exposure to high concentrations of these products because they cook more frequently than men.

Associations between criteria air pollutants and asthma

The evidence that asthma is increasing in prevalence is becoming increasingly compelling. This trend has been demonstrated not only in the United States, but also in the United Kingdom, New Zealand, Australia, and several other Western countries. In the United States, the increase is largest in the group under 18 years of age. There is mounting evidence that certain environmental air pollutants are involved in exacerbating asthma. This is based primarily on epidemiologic studies and more recent clinical studies. The U.S. Clean Air Act of 1970 provides special consideration to the class of outdoor air pollutants referred to as criteria pollutants, including O3, sulfur dioxide (SO2), particulate matter (PM), NOx, CO, and Pb. Standards for these pollutants are set by the U.S. Environmental Protection Agency with particular concern for populations at risk. Current evidence suggests that asthmatics are more sensitive to the effects of O3, SO2, PM, and NO2, and are therefore at risk. High SO2 and particulate concentrations have been associated with short-term increases in morbidity and mortality in the general population during dramatic air pollution episodes in the past. Controlled exposure studies have clearly shown that asthmatics are sensitive to low levels of SO2. Exercising asthmatics exposed to SO2 develop bronchoconstriction within minutes, even at levels of 0.25 ppm. Responses are modified by air temperature, humidity, and exercise level. Recent epidemiologic studies have suggested that exposure to PM is strongly associated with morbidity and mortality in the general population and that hospital admissions for bronchitis and asthma were associated with PM10 levels. In controlled clinical studies, asthmatics appear to be no more reactive to aerosols than healthy subjects. Consequently, it is difficult to attribute the increased mortality observed in epidemiologic studies to specific effects demonstrated in controlled human studies. Epidemiologic studies of hospital admissions for asthma have implicated O3 as contributing to the exacerbation of asthma; however, most study designs could not separate the O3 effects from the concomitant effects of acid aerosols and SO2. Controlled human clinical studies have suggested that asthmatics have similar changes in spirometry and airway reactivity in response to O3 exposure compared to healthy adults. However, a possible role of O3 in worsening atopic asthma has recently been suggested in studies combining allergen challenge following exposure to O3. Attempts at identification of factors that predispose asthmatics to responsiveness to NO2 has produced inconsistent results and requires further investigation. In summary, asthmatics have been shown to be a sensitive subpopulation relative to several of the criteria pollutants. Further research linking epidemiologic, clinical, and toxicologic approaches is required to better understand and characterize the risk of exposing asthmatics to these pollutants.

The prevalence of respiratory symptoms in South Australian preschool children. II. Factors associated with indoor air quality

OBJECTIVE

This study investigated the relationship between indoor air quality and the prevalence of respiratory symptoms in South Australian preschool children.

METHODOLOGY

Data were collected from 14,124 families with a child aged 4 years 3 months to 5 years of age. This sample represents 73% of the targeted State preschool population. At the time of a routine preschool health check, parents completed a questionnaire regarding: their child's respiratory health and place of residence (postcode), parental smoking, type of fuel used for cooking and heating and method used for home cooling.

RESULTS

For preschool children residing in the greater Adelaide region, logistic regression analyses found that having a natural gas stove compared to an electric stove was significantly associated with increased prevalence rates for: (i) asthma (odds ratio [OR] 1.24); (ii) wheezing in the preceding 12 months (OR 1.16); excessive colds (OR 1.14); and hay fever (OR 1.13). The use of a liquid petroleum gas stove compared to an electric stove was not associated with any respiratory symptoms. The use of a flueless gas heater compared to other forms of heating was significantly associated with increased prevalence rates for dry cough (OR 1.26), ever having wheezed (OR 1.15) and wheezing in the preceding 12 months (OR 1.18). The use of a wood fire/heater compared to other forms of heating was significantly associated with a reduced prevalence rate for dry cough (OR 0.84) and ever having wheezed (OR 0.82). Parental smoking was significantly associated with increased prevalence rates for bronchitis (OR 1.21) and ever having wheezed (OR 1.24). The form of home cooling used was not associated with prevalence rates, after accounting for geographic location. Socio-economic status (postcode level) was not generally associated with prevalence rates.

CONCLUSIONS

These results suggest that respiratory symptom prevalence is related to the fuel used for cooking and heating and parental smoking. Prospective investigation regarding indoor air quality and respiratory symptoms is required.

Predictive validity of the Readiness to Change Questionnaire

Following the development of the Readiness to Change Questionnaire described by Rollnick et al., this article reports on the predictive validity of the questionnaire among a sample of 174 male excessive drinkers identified by screening on wards of general hospitals. Relationships between patients' "stage of change" derived from questionnaires administered prior to discharge from hospital and changes in drinking behaviour at 8 weeks and 6 months follow-up are analysed. Allocated stage of change provided statistically significant relationships with drinking outcome. Multiple regression analysis showed that stage of change remained a significant predictor of changes in alcohol consumption when other possible predictors were taken into account. Two methods for allocating stage of change on the basis of questionnaire responses for use in different circumstances, a "quick" and a "refined" method, are described.

Nitrogen dioxide and respiratory illnesses in infants

Nitrogen dioxide is an oxidant gas that contaminates outdoor air and indoor air in homes with unvented gas appliances. A prospective cohort study was carried out to test the hypothesis that residential exposure to NO2 increases incidence and severity of respiratory illnesses during the first 18 months of life. A cohort of 1,205 healthy infants from homes without smokers was enrolled. The daily occurrence of respiratory symptoms and illnesses was reported by the mothers every 2 wk. Illnesses with wheezing or wet cough were classified as lower respiratory tract. Indoor NO2 concentrations were serially measured with passive samplers place in the subjects' bedrooms. In stratified analyses, illness incidence rates did not consistently increase with exposure to NO2 or stove type. In multivariate analyses that adjusted for potential confounding factors, odds ratios were not significantly elevated for current or lagged NO2 exposures, or stove type. Illness duration, a measure of illness severity, was not associated with NO2 exposure. The findings can be extended to homes with gas stoves in regions of the United States where the outdoor air is not heavily polluted by NO2.

Housing in early life and later mortality

STUDY OBJECTIVES

The aim was to examine the influence of domestic crowding and household amenities in early life on later mortality from all causes and specifically from stomach cancer, chronic obstructive pulmonary disease, and rheumatic heart disease.

DESIGN

This was a retrospective cohort study of people whose houses had been surveyed in 1936 and whose household size was known from the 1939 census. Subjects were followed through the National Health Service Central Register from 1951 to 1989.

SETTING

The housing survey had been carried out in the midland town of Chesterfield.

SUBJECTS

Subjects comprised 8138 men and women born after 1900.

RESULTS

A total of 2929 deaths were observed during the follow up period. All causes mortality in the full cohort was not consistently related to any of the housing variables examined, but among subjects who were still children at the time of the housing survey, death rates were higher in those whose houses were crowded or lacked a hot water tap. No associations could be shown between stomach cancer and domestic crowding or food storage facilities; chronic obstructive pulmonary disease and domestic crowding or use of gas for cooking; or rheumatic heart disease and domestic crowding. There were few deaths from these causes, however, in subjects who were children at the time of housing survey.

CONCLUSIONS

The findings suggest that the housing of young adults in Chesterfield during the 1930s had little effect on their later mortality. Further follow up of the cohort is needed before firm conclusions can be drawn about the influence of housing at younger ages.

Indoor nitrogen dioxide and childhood respiratory illness

Nitrogen dioxide is produced from the combustion of fossil fuels and as an emission from gas-fired appliances, and is also a component of tobacco smoke. Nitrogen dioxide has been shown in experimental animals to be toxic to the respiratory tract. A n number of recent studies have suggested that children exposed to significant levels of nitrogen dioxide in the home may be more susceptible to respiratory illness than children exposed to normal ambient levels. Respiratory illness is a major cause of morbidity in children everywhere. Here, we review the available evidence of this association and explore methodological issues in measurement of nitrogen dioxide exposure--misclassification of subjects, symptom bias and confounding. It has recently been shown that some New South Wales school rooms, where unflued gas heaters are often used as a source of warmth, have nitrogen dioxide levels which are above recommended ambient levels for outside air. This has underlined the need for setting standards for indoor levels of various pollutants, and cohort studies are suggested, to include personal monitoring and prospective data collection techniques.

Airways and air pollution in childhood: state of the art

Correlations between ambient pollutants and health effects, such as observed in SIDS, may in reality be to a larger extent the result of indoor sources. These distinctions between indoor and outdoor sources, while important, do not detract from the overall conclusion that pollution affects the airway in children directly and indirectly. Much still needs to be learned about the permanence of these effects, the mechanism by which the effect is mediated, and the conditions under which some of these effects are maximal. Two approaches seem particularly suited to shed further light on these issues. First, identification of biological markers for exposure to pollutants will yield both more accurate measures of exposure to pollutants and information about health consequences. Second, newer modeling techniques promise to predict health outcomes under a variety of environmental conditions. Shumway et al., for instance, describe a promising model predicting an increase in mortality due to ambient pollutants in the Los Angeles Basin with higher levels under extremes of temperature, especially during cold spells. Time series and factor analyses may further our knowledge as well. In the near future, large cohort studies should begin to reveal the cumulative effects of air pollution on the respiratory system, especially in relation to active smoking. Finally, studies in Black children are virtually unavailable. Given their high risk for respiratory illnesses, such studies are sorely needed.

Respiratory health effects of the indoor environment in a population of Dutch children

The effect of indoor exposure to nitrogen dioxide on respiratory health was studied over a period of 2 yr in a population of nonsmoking Dutch children 6 to 12 yr of age. Lung function was measured at the schools, and information on respiratory symptoms was collected from a self-administered questionnaire completed by the parents of the children. Nitrogen dioxide was measured in the homes of all children with Palmes' diffusion tubes. In addition, information on smoking and dampness in the home was collected by questionnaire. There was no relationship between exposure to nitrogen dioxide in the home and respiratory symptoms. Respiratory symptoms were found to be associated with exposure to tobacco smoke and home dampness. There was a weak, negative association between maximal midexpiratory flow (MMEF) and exposure to nitrogen dioxide. FEV1, peak expiratory flow, and MMEF were all negatively associated with exposure to tobacco smoke. Home dampness was not associated with pulmonary function. Lung function growth, measured over a period of 2 yr, was not consistently associated with any of the indoor exposure variables. The development of respiratory symptoms over time was not associated with indoor exposure to nitrogen dioxide. There was a significant association between exposure to environmental tobacco smoke in the home and the development of wheeze. There was also a significant association between home dampness and the development of cough.

Impedance tympanometry and the home environment in seven-year-old children

The distribution of tympanogram types among 872 seven-year-old children from a random population sample was related to 14 features of the home environment reported by parents in a questionnaire. Parental smoking was an important determinant of middle ear underpressure and effusion, and accounted for much of the associations observed with dampness, crowding and rented accommodation. Gas cooking was associated with a higher prevalence of effusion, but a lower prevalence of underpressure; this may deserve further study. After adjustment for seasonal variation, tenure and household smokers, the weekly mean temperature in the bedrooms of 34 children with Type B tympanograms was 18.2 degrees C, compared to 17.9 degrees C for 190 children with Type A tympanograms. The equivalent figures for bedroom relative humidity were 51.8 per cent and 52.7 per cent. It is unlikely that heating or ventilation of the home is an important determinant of middle ear effusion and underpressure in this age-group.

Housing and health: Indoor air quality

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Damp housing and childhood asthma: validation of reporting of symptoms

The relations among parental reports of respiratory symptoms, bronchospasm measured after exercise, and the presence of visible fungal mould in the home was assessed in a population sample of 7 year old children (n = 873). Wheeze in the past year was the symptom most closely associated with reported dampness and particularly with mould. The unadjusted odds ratio relating mould and wheeze was 3.70 (95% confidence interval 2.22 to 6.15), and after adjustment for housing tenure, number of people per room, number of smokers in the household, and gas cooking this remained highly significant (odds ratio 3.00 (1.72 to 5.25)). The reduction in forced expiratory volume in one second after six minutes of free running was used to validate reporting of wheeze. At all levels of measured bronchial lability wheeze was reported more commonly in the children from homes with mould. There was no significant difference in the degree of bronchospasm measured among children from homes with and without mould. Awareness of dampness or mould in the home may be a determinant of parental reporting of symptoms and may account for much of the observed association between mould and respiratory symptoms.

Association of infant alimentary and respiratory illness with parental smoking and other environmental factors

The incidences of alimentary and respiratory illnesses were observed during the first year of life in 1565 infants born in Tayside during 1980. Significant correlations (p less than 0.05) were found between each of these outcomes and parental smoking, maternal age, social class, method of infant feeding, and heating fuels. Multiple logistic regression indicated a significant independent effect of parental smoking was related separately to alimentary and to respiratory outcomes, the relative risks being of similar strength.