© 2004 American Public Health Association
John D. Spengler is with the Environmental Science and Engineering Program, Harvard School of Public Health, Boston, Mass. Jouni J. K. Jaakkola is with the Institute of Occupational Health, The University of Birmingham, Edgbaston, United Kingdom. Helen Parise is with the Department of Mathematics and Statistics, Boston University, Boston. Boris A. Katsnelson, Larissa I. Privalova, and Anna A. Kosheleva are with the Ural Region Environmental Epidemiology Center, Ekaterinburg, Russia. Correspondence: Requests for reprints should be sent to John D. Spengler, PhD, Environmental Science and Engineering Program, Harvard School of Public Health, PO Box 15677, Landmark Ctr, Rm 406 W, 401 Park Dr, Boston, MA 02215 (e-mail: spengler{at}hsph.harvard.edu).
Objectives. We studied housing characteristics, parental factors, and respiratory health conditions in Russian children. Methods. We studied a population of 5951 children from 9 Russian cities, whose parents answered a questionnaire on their childrens respiratory health, home environment, and housing characteristics. The health outcomes were asthma conditions, current wheeze, dry cough, bronchitis, and respiratory allergy. Results. Respiratory allergy and dry cough increased in association with the home being adjacent to traffic. Consistent positive associations were observed between some health conditions and maternal smoking during pregnancy, many health conditions and lifetime exposure to environmental tobacco smoke (ETS), and nearly all health conditions and water damage and molds in the home. Conclusions. Vicinity to traffic, dampness, mold, and ETS are important determinants of childrens respiratory health in Russia.
Numerous studies have associated indoor housing factors with increased prevalence of respiratory symptoms in children as well as adults.14 Yet there are few studies from the Russian Federation or the former Soviet Union, where a large percentage of the population live in concrete apartment buildings, in which water and heat are supplied by district heating systems and gas is used for cooking. Furthermore, most Russian families benefit from a state health care system that provides pre- and postnatal care.5 It therefore behooves us to examine housing factors such as smoking, moisture, indoor combustion sources (e.g., gas cooking, tobacco use), and ventilation on the health of school-aged children living in contemporary Russian housing.
Study Population The study population comprised 5951 8- to 12-year-old children in 9 Russian cities. Eight cities of the Sverdlovsk Oblast region and the city of Cherepovets in the Vologda Oblast participated in the study. Cities were selected to participate in a cross-sectional study of air pollution and childrens health. In 4 cities, 2 areas were selected1 to represent a more polluted area and 1 a less polluted area; in 5 cities, only 1 area was included. Within each area, 1 or 2 elementary schools were selected for participation. The principals of the selected schools were informed about the study and agreed to participate. Teachers were given verbal and written instructions, questionnaires, envelopes, and forms to record questionnaire distribution and collection. Parents were invited to a parents night where teachers explained the study and the conditions of consent. Teachers were instructed not to urge parents to fill out the questionnaire, as compliance was strictly voluntary. Parents who wished to participate completed the questionnaire either in the classroom or at home, and returned it (via the child) to the teacher in a sealed envelope. There was a 98% response rate. The questionnaires, which were identified by identification number only, were reviewed by the field coordinators for quality assurance and for encoding written replies. The questionnaires were then sent to the Harvard School of Public Health for optical scanning using internal consistency checks to identify questionnaires requiring additional verification. The questionnaire had been modified from previous European and North American questionnaires, which originated from respiratory health questionnaires of the British Medical Research Council and the American Thoracic Society.6 The questionnaire was composed of the following: the childs personal characteristics; the childs respiratory health, presence of atopic diseases, and number of infections during the past year; parents education and job category (as an indicator of socioeconomic status); parents smoking habits as well as respiratory and allergic diseases; and details of the home environment and building characteristics. Details of health, housing characteristics, and socioeconomic factors were adjusted for the current Russian conditions.
Health Outcomes
Exposure Assessment Exposure assessment was based on questionnaire information on housing characteristics. Questions inquired about the age of the building, the type of construction, and its proximity to traffic. Apartment-related factors included heating and cooking methods, presence of ventilation, and geographic orientation and size. Respondents reported on smoking within the apartment, water damage, presence of mold, and the number of occupants. Ancillary information on cleaning frequency, parental occupational exposures to chemicals, and parental income, as well as variables related to nonrespiratory health outcomes, was collected. Density indicators were derived from information on apartment size and number of occupants.
Covariates Used for Adjustment
Statistical Methods
The response rate across schools varied from 96% to 99% and averaged 98% overall. Half of the buildings/homes were constructed within the past 20 years, and 70% of the buildings were concrete high-rises. Eighty-five percent of the respondents lived in single-family apartments, of which 50% were smaller than 40 m2. Seventy-four percent of the children shared a bedroom. District heating plants provided heat and hot water requirements for 95% of the apartments/homes. Only 5% had a combustion heat source within their home. Gas was the cooking fuel for 80% of the homes, and 73% had no mechanical means of venting exhaust. Only 5% of the housing units had gas water heaters. Sixty percent of the respondents reported that their apartments did not face roadways. Almost 60% of the families reported having a furry pet at home. Toxic substance exposures of parents at the workplace were reported for 21.7% of the children, and 1.9% had parents with the potential for bringing toxic material home as they did not change their clothes at their workplace. Cleaning of homes was infrequent; nearly 80% said they cleaned less than once per month, with only 3.2% cleaning weekly. Water damage was reported for 22.4% of the living units, and 10.4% reported water damage within the past 12 months. The appearance or detection of molds within the past 12 months occurred in 10% of the homes. A small percentage of mothers (4.2%) admitted smoking during pregnancy. Environmental tobacco smoke (ETS) exposure at home at various stages of the childs lifeless than 2 years of age, 2 to 6 years of age, and currentlyoccurred for 45%, 51%, and 46% of the children, respectively. Additional variables were derived from smoking responses, occupancy, and size of the living unit. Exposure to ETS sometime during the childs life occurred for 63% of the children. We hypothesized that internal sources of air pollution, including airborne pathogens, might result in higher concentrations that vary inversely to volume of the residence or directly with crowding factors, based on occupant density. The area of the residence was separated by quartiles as a proxy for volume. The number of children and total number of occupants were divided by reported floor area and divided into quartiles to create 2 indicators of crowding.
The ORs for housing conditions are shown in Table 2
Those reporting a self-defined medium exposure to traffic outside their residence had higher prevalence of both respiratory allergy and eye irritation (nonsignificant). However, the cough and phlegm symptoms showed a significant positive association with traffic, with an apparent trend from light to medium traffic. Health outcomes were examined for internal heating, gas cooking, gas water heaters, and whether or not exhaust ventilation made any difference in response rates. Only 12 families had unvented gas water heaters, so these results were not reported. Although gas cooking and a combustion heating device were positively associated with increased symptoms, none reached significance. Having some form of exhaust ventilation reduced the risk for respiratory allergy and dry cough, but only the latter was significant (OR = 0.77 [95% CI = 0.64, 0.93]). For completeness, we examined other symptoms for the influence of combustion and exhaust ventilation and found that doctordiagnosed asthma and current asthma had a significant positive association with gas cooking. The adjusted ORs were 2.28 (95% CI = 1.04, 5.01) for current asthma and 2.12 (95% CI = 1.09, 4.11) for doctor-diagnosed asthma. Although the severity of asthma and the various wheeze-related outcomes all had positive adjusted ORs, none were significant at the 95% CI.
In examining all smoking variables, we found for the most part that all adjusted ORs across all outcomes showed positive associations with smoking exposure variables. Current dry cough showed significant associations, as did ever cough, persistent cough, and persistent dry cough. Experiencing a respiratory tract infection within the past year was associated with ETS exposure sometime in the childs life but not necessarily with current smoking in the home. Doctor-diagnosed bronchitis was strongly associated with lifetime ETS exposure (OR = 1.26 [95% CI = 1.10, 1.44]), but not for bronchitis within the past year. Table 3
The housing conditions with the strongest and most consistent associations with health outcomes were reported moisture (water damage) and the presence of molds on surfaces. Table 4
Having any furry pet was strongly protective for respiratory allergy (OR = 0.61 [95% CI = 0.50, 0.74]) but less so for severe wheezing (OR = 0.84 [95% CI = 0.74, 1.01]) and current bronchitis (OR = 0.86 [95% CI = 0.67, 1.00]). Having a furry pet was strongly negatively associated with current asthma (OR = 0.40 [95% CI = 0.25, 0.64]), whereas having a cat was specifically associated with higher rates of doctor-diagnosed asthma (OR = 3.29 [95% CI = 1.01, 10.72]) but not with asthma symptoms (OR = 1.06 [95% CI = 0.78, 1.44]). Examining the relationship between parental exposures to toxic material at work and their childrens symptoms yielded interesting results. Even though only about 2% of the responding parents had workplace exposures, there were significant associations with dry cough (OR = 2.35 [95% CI = 1.54, 3.59]), persistent dry cough (OR = 2.18 [95% CI = 1.05, 4.55], and severe wheezing (OR = 1.76 [95% CI = 1.03, 3.02]). Reported frequency of house cleaning revealed no consistent or significant relationships.
Consistent with similar health surveys conducted in the United States and Europe, conditions of mold and dampness in living areas are strongly associated with increased respiratory symptoms. In an examination of all published literature, a Nordic scientific review panel concluded that the presence of dampness in a home increased the reporting of cough, wheeze, and respiratory symptoms by 40% over a reference population.3 The risk appears to be similar for Russian housing. However, the prevalence of moisture and mold in the housing stock is approximately half of the prevalence reported for surveys done in the United States and Canada.7,8 Jacob et al.9 showed that high counts of Cladosporium and Aspergillus spores in house dust were associated with increased risk of allergic sensitization. Their results suggest that higher spore counts, particularly in the winter, are likely to increase the prevalence of allergic symptoms in children. Cook and Strachan10 conducted pooled analysis of ORs for parental smoking on asthma, wheeze, chronic cough, chronic phlegm, and shortness of breath symptoms in children exposed to ETS. Our Russian results for ever cough, persistent cough, dry cough, and persistent dry cough are similar to the pooled ORs for cough (OR = 1.35 [95% CI = 1.13, 1.62]). Also, our findings for phlegm were similar to the pooled ORs of 1.31 (95% CI = 1.08, 1.59). Asthma and wheeze, although both significantly associated with parental smoking in the pooled analysis, were not significantly associated with any measure of ETS exposure over the childs life. Gilliland et al.11 reported that in utero exposure to maternal smoking without subsequent postnatal ETS exposure significantly increased the association with doctor-diagnosed asthma, asthma symptoms, and asthma severity later in a childs life, as well as most of the wheezing outcomes. Our ORs for asthma and wheeze outcomes were all positively associated with smoking during pregnancy (approximately 2.0) but did not reach P < 0.05 significance. Given the lack of specificity to the smoking questions asked in this survey, it is not possible to ascertain the separate influence of maternal versus paternal smoking or even age-related responses seen in other studies. Gilliland et al.11 similarly showed that current and previous ETS exposure was not associated with asthma prevalence but was consistently associated with various wheezing variables. Apelberg et al.12 performed a meta-analysis of the studies on the effect of early exposure to household pets on the development of asthma and asthma-related symptoms. Inappropriate time sequence of the exposure and outcome information, typical for cross-sectional studies, was an important source of heterogeneity and an indication of potential selection bias. In studies ensuring a meaningful temporal relation between exposure and outcome, the pooled risk estimates for both asthma (fixed-effects OR = 1.11 [95% CI = 0.98, 1.25]; P = 0.04) and wheeze (OR = 1.19 [95% CI = 1.05, 1.35]; P = 0.03) indicated a small effect. However, the effect was limited to studies with a median study population age greater than 6 years. In younger children, the effect appeared protective for wheezing (OR = 0.80 [95% CI = 0.59, 1.08]; P = 0.38). The authors concluded that the observed lower risk among exposed compared to unexposed young children is consistent with a protective effect in this age group, but could also be explained by selection bias. In a prospective study of asthma incidence in adolescents, McConnell et al.13 reported a relative risk of 1.6 (95% CI = 1.0, 2.5) for having a furry pet at home. The present study was cross-sectional and did not inquire precisely when the pet had been present. Therefore, the negative associations between the presence of pets and the risk of asthma and allergies could be a result of either avoidance or removal of pets in families with children allergic to respiratory allergens and with asthma problems. Exposure to nitrogen dioxide (NO2) from gas cooking is a common experience for the majority of children in this survey. From studies that measured NO2 indoors, it can be inferred that concentrations will be higher in the absence of exhaust vents. Yet examining possible interactive effects for cooking fuel and ventilation offered no evidence for increased association with the inferred exposure gradient (e.g., not using gas but having ventilation versus having gas but not having ventilation). Garrett et al.14 reported that gas stoves increased the risk of respiratory symptoms in children (OR = 2.3 [95% CI = 1.0, 5.2]), whereas the association with direct measures of NO2 was marginal. Shima and Adachi15 reported that the prevalence of bronchitis wheeze and asthma significantly increased with indoor NO2 exposures among girls but not among boys. They also showed that wheeze and asthma incidence were associated with outdoor NO2 but not indoor NO2. Examining the effects of NO2 from gas heaters in school rooms, Pilotto et al.16 found significant increases in sore throats, colds, and absences from school when hourly peak exposures exceeded 80 ppb compared with background levels of 20 ppb. In a large study of respiratory infections among 1000 infants in Albuquerque, New Mexico, Samet et al.17 found no associations for either gas stove or NO2 levels measured in the kitchen or the childs bedroom. This study of Russian schoolchildren and housing factors poses some interesting observations for further investigation. Only 40% of the respondents reported either light or medium traffic outside their homes/apartments. Persistent cough, phlegm, and dry cough, as well as the prevalence of severe upper respiratory infection in children, were positively associated with medium traffic loadings compared with not living along any roadways. Clustered apartment complexes removed from roadways are common in many Russian cities; it is a situation unlike that of any study reporting associations with asthma and respiratory symptoms for children living close to heavily traveled roads. In US, Western European, and Japanese studies, the reference group always has approximate exposure to some road traffic.15,1824 In this Russian study, none of the asthma or wheeze variables showed an association with subjective reporting of traffic exposure. Nevertheless, the possible association of vehicle exhaust on chronic cough and phlegm cannot be dismissed. Just 1.9% of the children had 1 or both parents reporting occupational contact with potentially toxic substances and not leaving their work clothes at the job site. Another 19.75% had parents who might be exposed but leave their clothing at work. Consistently positive associations were found for wheezing (severe and current) and most of the coughs (persistent dry cough, dry cough, usual cough) as well as asthma-like symptoms and general atopy. These observations suggest that compounds may be carried home on clothing or absorbed in fibers of clothing, leading to children being exposed at home. Many metallurgical and chemical production facilities are located in Cherepovets and throughout Sverdlovsk Oblast. It is likely that some parents are heavily exposed to potentially irritating or toxic materials at work. Although doctor-diagnosed asthma rates for Russian children were substantially lower than rates children are currently experiencing in the West, the rates are consistent with reports from former Soviet Bloc countries. Jedrychowski et al.25 reported doctor-diagnosed asthma among 1129 9-year-old children living in Krakow, Poland, as 1.9% for girls and 2.4% for boys in 1995. The International Study of Asthma and Allergies in Childhood showed that the variation in the prevalence of asthma and selfreported asthma symptoms between different countries is striking.26 In these comparisons the prevalences of all the studied indices of asthma were lower in Eastern than in Western Europe. Corresponding figures for asthma symptoms from video questionnaires were 2% in Russia and between 12% and 20% in the United Kingdom, the United States, Canada, New Zealand, and Australia. Differences in access to health care, diagnostic practice, and environmental and dietary factors are plausible explanations for the large variation in the prevalences of asthma between Russia and Western Europe/North America. Rates for other conditions and symptoms in Russian children are comparable to rates reported from studies conducted in the United States. In the Harvard 24 Cities Study of air pollution and childrens health in 24 North American towns,27 33% of the children reported some atopy. The reporting of current asthma symptoms within the past year ranged from 3% to 11% of the children across 24 communities, with persistent wheeze ranging from 4% to 12%. For Russian children, asthma-like symptoms were 10%, with a higher rate of current wheeze (13.4%). Chronic cough in the 24 Cities Study ranged from 4% to 9%, which is consistent with the 5.5% noted in our study. Parents reported chronic bronchitis in the past year at rates of 3% to 10% across the 24 Cities Study, and a rate of 8.3% for our Russian children. The respiratory symptoms in children associated with ETS exposure, water damage, and presence of molds in the Russian housing study were consistent with reports on housing conditions in many other countries. Russian housing is characterized by large, concrete high-rise structures. Apartments are similar in layout and size, and are served by district hot water for heating and gas for cooking; mechanical ventilation and air conditioning is a rarity. Our study reporting prevalences of conditions and associated health symptoms provides important insights that are applicable to millions of children living in similar housing.
This study was supported by a World Bank loan to the Russian Federation and administered under the environmental epidemiology component of the Centre for Preparation and Implementation of International Projects on Technical Assistance, managed by Vladislav Furman, PhD, with assistance from Victor Kislitsin, PhD, and Natalia Lebedeva, MD, DSc. Analyses were partially supported by the National Institute of Environmental Health Sciences (NIEHS) Center for Environmental Health at the Harvard School of Public Health (grant ES000002); the contents of our analyses are solely the responsibility of the authors and do not necessarily represent the official views of the NIEHS. We thank the parents who gave their time to complete questionnaires and the teachers who distributed and efficiently collected the surveys. We are indebted to our colleagues in the Ural Region Environmental Epidemiology Center, who, under the direction of Sergey Kuzmin, MD, DSc, conducted a successful comprehensive study of air pollution and childrens health in 9 Russian cities. The advice and contributions of Olga Malykh, MD, CSc, Boris Nikonov, MD, DSc, and Vladimir Gurvitch, MD, CSc, were greatly appreciated. Haluk Ozkaynak, PhD, and Thomas Dumyahn, MS, both of the Harvard School of Public Health at the time of the study, contributed substantially to the design and management of the environmental epidemiology assistance program with Russia.
Human Participant Protection
Contributors J. D. Spengler designed the study and led the analysis and the writing of the article. J. J. K. Jaakkola helped design and oversee the study and analysis, and participated in the writing of the article. H. Parise and A. A. Kosheleva analyzed the data. B. A. Katsnelson and L. I. Privalova helped design and conduct the study, managed staff, checked records, and participated in data analysis. Accepted for publication April 16, 2003.
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