Biomedical subjects

Jordi Sunyer

Publications and source records attributed to Jordi Sunyer.

At least 37 records · Page 2Linked to original sources

PubMed2005

Latitude, birth date, and allergy.

BACKGROUND: The space and time distribution of risk factors for allergic diseases may provide insights into disease mechanisms. Allergy is believed to vary by month of birth, but multinational studies taking into account latitude have not been conducted. METHODS AND FINDINGS: A questionnaire was distributed in 54 centres to a representative sample of 20- to 44-y-old men and women mainly in Europe but also including regions in North Africa, India, North America, Australia, and New Zealand. Data from 200,682 participants were analyzed. The median prevalence of allergic rhinitis was 22%, with a substantial variation across centres. Overall, allergic rhinitis decreased with geographical latitude, but there were many exceptions. No increase in prevalence during certain winters could be observed. Also, no altered risk by birth month was found, except borderline reduced risks in September and October. Effect estimates obtained by a multivariate analysis of total and specific IgE values in 18,085 individuals also excluded major birth month effects and confirmed the independent effect of language grouping. CONCLUSION: Neither time point of first exposure to certain allergens nor early infections during winter months seems to be a major factor for adult allergy. Although there might be effects of climate or environmental UV exposure by latitude, influences within language groups seem to be more important, reflecting so far unknown genetic or cultural risk factors.

Adult↗

PubMed2005

Lung function decline, chronic bronchitis, and occupational exposures in young adults.

RATIONALE: Occupational exposures to vapors, gas, dust, or fumes have been shown to be a risk factor of airway obstruction in cross-sectional studies in the general population. OBJECTIVES: Our aim was to study the relationships between specific occupations and occupational exposures during a 9-yr follow-up period and changes in lung function and symptoms of chronic bronchitis. METHODS: Subjects from the general population aged 20 to 45 yr were randomly selected in 1991-1993 within the European Community Respiratory Health Survey. Follow-up took place from 1998 to 2002 among 4,079 males and 4,461 females in 27 study centers. A total of 3,202 men and 3,279 women twice completed lung function measurements. Job history during follow-up was linked to a job exposure matrix and consequently translated into cumulative exposure estimates. MAIN RESULTS: Individuals exposed to dusts, gases, and fumes during the period of follow-up did not have a steeper decline of FEV1 than did individuals with consistently white-collar occupations without occupational exposures (relative change among men and women, + 1.4 and -3.1 ml/yr, respectively; p > 0.2), nor an increase of prevalence or incidence of airway obstruction defined as an FEV1/FVC ratio of less than 0.7. The incidence of chronic phlegm increased in men exposed to mineral dust (relative risk, 1.94 [1.29-2.91]) and gases and fumes (relative risk, 1.53 [0.99-2.36]), which was not modified by smoking. CONCLUSION: Occupational exposures to dusts, gases, and fumes occurring during the 1990s are associated with incidence of chronic bronchitis, although these did not impair lung function in a population of relatively young age.

Adult↗

PubMed2005

An increase in bronchial responsiveness is associated with continuing or restarting smoking.

RATIONALE: Bronchial responsiveness (BHR) has been found to be associated with smoking, atopy, and lower lung function in cross-sectional studies, but there is little information on determinants of change in adults. OBJECTIVES: To analyze change in bronchial responsiveness in an international longitudinal community study. METHODS: The study was performed in 3,993 participants in the European Community Respiratory Health Survey who had bronchial responsiveness measured in 1991-1993, when aged 20 to 44 yr, and in 1998-2002. MEASUREMENTS: Bronchial responsiveness was assessed by methacholine challenge. Serum samples were tested for total IgE, and for specific IgE to four common allergens. Smoking information was obtained from detailed administered questionnaires. Change in bronchial responsiveness was analyzed by change in IgE sensitization, smoking, and lung function, with tests of interaction terms with age and sex. MAIN RESULTS: Continuing and restarting smokers had increasing bronchial responsiveness, approximately equivalent to a mean reduction in PD20 of 0.68 and 0.75 doubling doses, respectively, over 10 yr, in addition to a small increase explained by decline in FEV1. No other risk factor for change in bronchial responsiveness was identified. CONCLUSIONS: Smoking is a risk factor for increasing bronchial responsiveness over and above the effect of decreasing lung function. Neither baseline IgE sensitization nor change in sensitization was shown to be a risk factor for increasing BHR, the latter possibly due to little overall increase or decrease in sensitization.

Adult↗

PubMed2005

A case-crossover analysis of out-of-hospital coronary deaths and air pollution in Rome, Italy.

RATIONALE: Out-of-hospital coronary heart disease death is a major public health problem, but the association with air pollution is not well understood. OBJECTIVES: We evaluated the association between daily ambient air pollution levels (particle number concentration [PNC]--a proxy for ultrafine particles [diameter < 0.1 microm], mass of particles with diameter less than 10 microm [PM10]; CO, NO2, and O3) and the occurrence of fatal, nonhospitalized coronary events. METHODS: Subjects were 5,144 out-of-hospital fatalities (410-414, International Classification of Diseases-9; 1998-2000) who had been residents of Rome. Hospitalizations during the 3 yr before death were considered to identify comorbidities (e.g., diabetes, hypertension, heart failure, dysrhythmia, chronic obstructive pulmonary disease). Statistical analyses were performed using a case-crossover design. MEASUREMENTS AND MAIN RESULTS: The association with out-of-hospital coronary deaths was statistically significant for PNC, PM10, and CO. Air pollution on the day of death had the strongest effect (e.g., 7.6% increase [95% confidence interval, 2.0-13.6%]) for an interquartile range of PNC, 27,790 particles/cm3. The 65-74- and 75+-yr age groups were at higher risk than the 35-64-yr age group, and there was a suggestion of effect modification for people with hypertension and chronic obstructive pulmonary disease. CONCLUSIONS: Air pollutants originating from combustion processes, including ultrafine particles, are related to fatal, nonhospitalized coronary events. The effect is stronger among people over 65 years of age, but is not limited to a group with a specific comorbidity.

Aged↗

PubMed2005

Comparison of self-reported occupational exposure with a job exposure matrix in an international community-based study on asthma.

BACKGROUND: Self-reports are frequently used to assess occupational exposures in epidemiological studies on asthma, but the validity and influence of asthma status on performance is unclear. METHODS: Data on self-reported exposure to air pollutants were obtained for 16,752 randomly selected working individuals from 40 study centers, and compared to exposures obtained by a job exposure matrix (JEM). The influence of current asthma symptoms or medication was investigated. RESULTS: Specificity of self-reports amounted to 0.83 and 0.87, and sensitivity 0.48 and 0.42 for asthmatics and non-asthmatics, respectively, when compared with the JEM. Self-reported exposure, but not exposure assessed by the JEM, was more prevalent in areas with a higher community prevalence of asthma. CONCLUSIONS: The prevalence of self-reported occupational exposures seems to depend on asthmatic health status at both the individual and the community level. Associations between self-reports and asthma are likely to be biased, especially in pooled analyses combining different areas with varying prevalence rates of asthma.

Adult↗

PubMed2005

Breastfeeding and concentrations of HCB and p,p'-DDE at the age of 1 year.

Exposure to organochlorine compounds (OCs) occurs both in utero and through breastfeeding. Levels of hexachlorobenzene (HCB) in the cord serum of newborns from a population located in the vicinity of an electrochemical factory in Spain are among the highest ever reported. We aimed to assess the degree of breast milk contamination in this population and the subsequent exposure of children to these chemicals through breastfeeding. A birth cohort including 92 mother-infant pairs (84% of all births in the study area) was recruited between 1997 and 1999 in five neighboring villages. OCs were measured in cord serum, colostrum, breast milk, and children's serum at 13 months of age. Concentrations of OCs were detected and quantified in all colostrum and milk samples. The concentrations in mature milk were lower than those encountered in colostrum. At 13 months of age the highest concentration of OC was found for dichlorodiphenyl dichloroethane (p,p'-DDE), in contrast to what these children presented at birth, where HCB was the highest compound. Those infants who were breastfed had higher concentrations at the age of 1 than those who were formula fed (2.13 ng/mL of HCB among formula feeders vs 4.26 among breast feeders, and 1.95 of p,p'-DDE vs 6.00 (P<0.05)). Long-term breastfeeding leads to a dose-response increase of the concentrations in children's serum during the first year of life.

Air Pollutants↗

PubMed2005

Change in prevalence of IgE sensitization and mean total IgE with age and cohort.

BACKGROUND: Cross-sectional studies show that the prevalence of IgE sensitization is lower in older age groups than younger age groups. This could reflect either a decrease in sensitization with aging or a higher prevalence of sensitization in more recent birth cohorts. OBJECTIVE: To assess change in IgE sensitization and mean total IgE in young adults as they age. METHODS: Serum specific IgE to common allergens and total IgE were measured on 2 occasions about 9 years apart in 6371 young adults living in 28 centers, mainly in Western Europe, who took part in the European Community Respiratory Health Survey II. Outcomes were analyzed by using generalized estimating equations, and adjustments were made for differences between laboratory measures on the 2 occasions. RESULTS: Overall, there was no net change in the prevalence of sensitization to at least 1 of house dust mite, grass, or cat (net change per 10 years of follow-up, -0.1%; 95% CI, -1.7% to 1.5%), although there was a fall in mean total IgE (ratio of geometric mean total IgE, 0.86; 95% CI, 0.79 to 0.93). There was evidence that sensitization to at least 1 allergen was higher in more recent cohorts, and this was largely explained by a higher prevalence of sensitization to grass. CONCLUSION: The disease burden associated with IgE sensitization in adults, and particularly with IgE sensitization to grass, is likely to continue to increase for some time despite current evidence that the increase in allergy seen in children may have ceased.

Adult↗

PubMed2005

Aerosol particle number concentration measurements in five European cities using TSI-3022 condensation particle counter over a three-year period during health effects of air pollution on susceptible subpopulations.

In this study, long-term aerosol particle total number concentration measurements in five metropolitan areas across Europe are presented. The measurements have been carried out in Augsburg, Barcelona, Helsinki, Rome, and Stockholm using the same instrument, a condensation particle counter (TSI model 3022). The results show that in all of the studied cities, the winter concentrations are higher than the summer concentrations. In Helsinki and in Stockholm, winter concentrations are higher by a factor of two and in Augsburg almost by a factor of three compared with summer months. The winter maximum of the monthly average concentrations in these cities is between 10,000 cm(-3) and 20,000 cm(-3), whereas the summer min is approximately 5000-6000 cm(-3). In Rome and in Barcelona, the winters are more polluted compared with summers by as much as a factor of 4-10. The winter maximum in both Rome and Barcelona is close to 100,000 cm(-3), whereas the summer minimum is > 10,000 cm(-3). During the weekdays the maximum of the hourly average concentrations in all of the cities is detected during the morning hours between 7 and 10 a.m. The evening maxima were present in Barcelona, Rome, and Augsburg, but these were not as pronounced as the morning ones. The daily maxima in Helsinki and Stockholm are close or even lower than the daily minima in the more polluted cities. The concentrations between these two groups of cities are different with a factor of about five during the whole day. The study pointed out the influence of the selection of the measurement site and the configuration of the sampling line on the observed concentrations.

Aerosols↗

PubMed2005

Smoking habit, respiratory symptoms and lung function in young adults.

BACKGROUND: Smoking is the primary cause of deterioration in forced expiratory volume (FEV(1)) and the development of chronic obstructive lung disease. This study assessed the independent association of smoking with respiratory symptoms and lung function in young adults who took part in the European Community Respiratory Health Survey (ECRHS-I). METHODS: Cross-sectional multi-centre survey of a general population of young adults aged 20(44 years in the ECRHS(I conducted in five Spanish centres. Several groups were created in an exclusive and descendent manner from the subjects who completed the questionnaire in accordance with how they had answered the questions: asthma-related symptoms; chronic bronchitis symptoms; minor respiratory symptoms; chronic cough; and no respiratory symptoms. Among a subset of the population, forced spirometry tests were performed. Linear and logistical regression models were used to assess the relationship of smoking in the presence of symptoms and its impact on lung function, adjusted by other important variables. RESULTS: The prevalence of respiratory symptoms was higher among smokers. After adjusting for geographical area, total IgE, age, sex, and FEV(1), smoking was associated with an increased risk of chronic bronchitis and other respiratory symptoms. These risks increased with increasing number of cigarettes smoked per day. A deterioration of FEV(1) and the FEV(1)/FVC ratio was also directly associated with the number of cigarettes smoked per day. CONCLUSION: Even among young adults, smoking confers a high risk of developing a number of respiratory symptoms and the deterioration of the ventilatory function.

Adult↗

PubMed2005

Estimating the exposure-response relationships between particulate matter and mortality within the APHEA multicity project.

Several studies have reported significant health effects of air pollution even at low levels of air pollutants, but in most of theses studies linear nonthreshold relations were assumed. We investigated the exposure-response association between ambient particles and mortality in the 22 European cities participating in the APHEA (Air Pollution and Health--A European Approach) project, which is the largest available European database. We estimated the exposure-response curves using regression spline models with two knots and then combined the individual city estimates of the spline to get an overall exposure-response relationship. To further explore the heterogeneity in the observed city-specific exposure-response associations, we investigated several city descriptive variables as potential effect modifiers that could alter the shape of the curve. We conclude that the association between ambient particles and mortality in the cities included in the present analysis, and in the range of the pollutant common in all analyzed cities, could be adequately estimated using the linear model. Our results confirm those previously reported in Europe and the United States. The heterogeneity found in the different city-specific relations reflects real effect modification, which can be explained partly by factors characterizing the air pollution mix, climate, and the health of the population.

Air Pollutants↗

PubMed2005

Prenatal dichlorodiphenyldichloroethylene (DDE) and asthma in children.

Prevalence of asthma increases with increasing dichlorodiphenyldichloroethylene (DDE) levels. However, the effect of early-life exposure, the fundamental window of exposure, is unknown. We assessed the association between prenatal DDE and other organochlorine compounds, and atopy and asthma during infancy. All women presenting for antenatal care in Menorca (Spain) over 12 months starting in mid-1997 were invited to take part in a longitudinal study; 482 children were subsequently enrolled, and 468 (97.1%) provided complete outcome data up to the fourth year of study. Prenatal exposure of organochlorine compounds was measured in cord serum in 405 (83%) children. Asthma was defined on the basis of wheezing at 4 years of age, persistent wheezing, or doctor-diagnosed asthma. We measured specific immunoglobulin-E (IgE) against house dust mite, cat, and grass in sera extracted at 4 years of age. DDE (median = 1.03 ng/mL) was detected in all children, as well as hexachlorobenzene (0.68 ng/mL) and polychlorobiphenyls (0.69 ng/mL). Wheezing at 4 years of age increased with DDE concentration, particularly at the highest quartile [9% in the lowest quartile (< 0.57 ng/mL) vs. 19% in the highest quartile (1.90 ng/mL); relative risk = 2.63 (95% confidence interval 1.19-4.69), adjusting for maternal asthma, breast-feeding, education, social class, or other organochlorines]. The association was not modified by IgE sensitization and occurred with the same strength among nonatopic subjects and among those with persistent wheezing or diagnosed asthma. DDE was not associated with atopy alone. Prenatal exposure to DDE residues may contribute to development of asthma.

Antigens↗

PubMed2005

Radiologically recognized pleural changes in nonpneumoconiotic silica-exposed coal miners.

OBJECTIVES: Whether nonpneumoconiotic silica-exposed coal miners develop radiologically recognizable pleural changes was studied. METHODS: In a retrospective follow-up study, the oldest and the most recent chest X-rays of 765 workers with a profusion category lower than 1/0 according to the International Labour Office were read. RESULTS: Altogether 720 (94.1%) workers had no abnormalities, and 45 (5.9%) showed some pleural alteration in the first X-ray. In 43 (6%) of the 720 with no initial abnormalities, some pleural change was detected in the last X-ray. There was a statistical difference (P = 0.022) according to silica exposure category [low: 5 (2.4%); medium: 8 (6%); high: 30 (8%)]. The relative risk for any pleural alteration was significantly increased in relation to the silica-exposed group [medium: odds ratio (OR) 5.72, 95% confidence interval (95% CI) 1.4-23.5, P = 0.016; high: OR 7.62, 95% CI 2.1-27.2, P = 0.002] and to rib alterations (OR 3.74, 95% CI 1.4-9.7, P = 0.007). In 19 (2.6%) workers with no alterations initially, a costophrenic sinus alteration was detected later. Again the silica exposure categories [low: 1 (0.5%); medium: 3 (2.2%); high: 15 (4.2%)] differed significantly (P = 0.033). The relative risk of costophrenic sinus obliteration was significantly increased in relation to the silica-exposed group [medium: OR 8.59, 95% CI 0.7-113, P = 0.102; high: OR 16.44, 95% CI 1.5-177, P = 0.021]. The appearance of two costophrenic sinus obliterations and the disappearance of four were detected in the last chest X-ray of the 45 workers with some pleural alteration initially. CONCLUSIONS: Costophrenic sinus obliteration can be found in nonpneumoconiotic silica-exposed coal miners and seems to be associated with silica exposure intensity.

Adult↗

PubMed2004

Socioeconomic status and asthma prevalence in young adults: the European Community Respiratory Health Survey.

The authors assessed the association between asthma prevalence and socioeconomic status at both the individual and center levels simultaneously.by using data from 32 centers in 15 countries. Included were 10,971 subjects aged 20-44 years selected from the general population and interviewed in 1991-1992. Socioeconomic status at both the individual and aggregated levels was measured on the basis of occupation and educational level. Associations were assessed by using multilevel models adjusted for age, sex, body mass index, parental asthma, childhood respiratory infections, presence of immunoglobulin E to common allergens, rhinitis, smoking, and occupational exposure to irritants. Asthma prevalence was higher in lower socioeconomic groups, whether defined by educational level (odds ratio for finishing full-time studies-<16 vs. >19 years = 1.28, 95% confidence interval: 1.00, 1.64) or social class (odds ratio for semiskilled and unskilled manual workers vs. professional/managerial = 1.51, 95% confidence interval: 1.20, 1.90), regardless of atopic status. The relation was consistent between centers. Irrespective of individual socioeconomic status, subjects living in areas in which educational levels were lower had a higher risk of asthma (p < 0.05). This center-level association partially explained geographic differences in asthma prevalence, but considerable heterogeneity still remained. The authors concluded that community influences of living in a low-educational area are associated with asthma, independently of subjects' own educational level and social class.

Adult↗

PubMed2004

A prospective study of Fel d1 and Der p1 exposure in infancy and childhood wheezing.

The impact of domestic exposure to cat allergen (Fel d1) and house dust mite (Der p1) on wheezing from birth to the age of 4 years was investigated in a multicenter prospective birth cohort; 1,611 mothers were recruited before delivery in Ashford, England, and Barcelona and Menorca, Spain. Exposures were gathered via dust sample collection at children's home in their first year of life. Families provided complete outcome data (wheezing status in all 4 years) for 1,289 children. Domestic allergen levels varied substantially between centers. Six hundred three (47%) children never wheezed during their first 4 years of life. Der p1 did not correlate with any type of wheezing outcome. Fel d1 significantly increased the risk of wheezing in 3- and 4-year-olds in comparison to 1-year-olds. Distinct risk profiles were found for wheezing at different ages. Multivariate analysis revealed an interaction between Fel d1 and maternal asthma among children who wheeze in Year 4 (relative risk = 2.77; 95% confidence interval = 1.19-6.46). Our data support the idea that several patterns of wheezing with different risk profiles exist among young children. The effect of Fel d1 exposure varied according to age and maternal asthma.

Animals↗

PubMed2004

Geographic variations in the effect of atopy on asthma in the European Community Respiratory Health Study.

BACKGROUND: Atopy has long been related to asthma. The prevalences of both atopy and asthma have shown substantial variation. OBJECTIVE: We sought to assess geographic variations in the fraction of asthma attributable to IgE sensitization to specific allergens in the European Community Respiratory Health Survey. METHODS: A cross-sectional study was undertaken during the years 1991 and 1992 on 13,558 individuals in 36 centers in 16 countries. Asthma was defined in several ways, variously incorporating reported symptoms, bronchial responsiveness to methacholine, and physician diagnosis. Specific IgE against house dust mite (Dermatophagoides pteronyssinus), cat, timothy grass, Cladosporium herbarum , and a local allergen (birch, Parietaria judaica , or ragweed) were measured. RESULTS: The overall attributable fraction (AF) of asthma symptoms caused by atopy was 30% but varied widely between centers, ranging from 4% to 61%. The overall AF increased to 43% when asthma was based on wheezing and bronchial responsiveness, to 45% with a physician diagnosis of asthma, and to 48% when the patient reported more than 12 attacks in the last year. Between centers, the AF for atopy was significantly correlated with the prevalence of atopy among the asthmatic patients ( r = 0.91) and with the sensitization to house dust mite ( r = 0.64), as well as with the prevalence of asthma among atopic individuals ( r = 0.43) and the prevalence of asthma among nonatopic individuals ( r = -0.51). CONCLUSION: The effect of atopy on the prevalence of asthma varies widely between centers, probably because of variations in factors related to the expression of asthma and to the prevalence of sensitization, particularly to house dust mite.

Allergens↗

PubMed2004

Relations between respiratory symptoms and spirometric values in young adults: the European community respiratory health study.

We aim to assess whether respiratory symptoms are associated with lung function in young adults, and whether any such relation is similar in those with asthma, in men and women, and in different countries. Study participants (aged 20-44 years) were randomly selected from the general population in 35 centres in 15 countries as part of the European Community Respiratory Health Study. In all, 12,541 subjects (47%) completed a respiratory symptoms questionnaire and spirometry, metacholine challenge and immunoglobulin E tests. Indicators of diagnosed asthma showed the largest association with airways obstruction (FEV1--maximal 1-s forced expiratory volume/forced vital capacity--FVC < 70%), followed by symptoms of wheezing or shortness of breath, in both genders. Among the 96% of subjects whose FEV1/FVC ratios were greater or equal to 70%, wheezing or shortness of breath was associated with lower FEV1 levels (-211 ml in men and -169 ml in women (P < 0.01)), independent of diagnosed asthma, smoking, atopy or bronchial responsiveness. This association was not explained by a lower FVC. Symptoms of chronic bronchial mucus hypersecretion (chronic phlegm) were unrelated to both airways obstruction and FEV1 levels. Findings were homogeneous across all centres. These results suggest that lung diseases that cause wheezing are generally associated with impaired lung function.

Adult↗

PubMed2004

Evaluation of specific occupational asthma risks in a community-based study with special reference to single and multiple exposures.

OBJECTIVES: To compare two job exposure matrices (JEMs) for the evaluation of asthma risks related to specific occupational exposures in a community-based study. METHODS: A questionnaire on self-reported asthma, respiratory symptoms and current occupation was sent to the participants of the European Community Respiratory Health Survey in five areas in Spain. Both an asthma-specific JEM, including expert judgment steps and a general JEM, were applied to occupational codes. Risks of current asthma symptoms and wheeze in the last year associated with the obtained exposure estimates were evaluated. Correlations between specific exposures were investigated using explanatory factor analysis. RESULTS: Occupational exposures to the high-molecular-weight (MW) agents flour dust, enzymes, mites and animal-derived proteins as obtained by the asthma-specific JEM were positively associated with asthma outcomes. The effect of additional expert judgment steps was limited. High exposures to biological dust assessed by the general JEM without expert judgment was also associated with asthma. Many of the exposed individuals worked in environments with multiple exposures. CONCLUSIONS: Asthma risks associated with occupational exposures to specific high-MW agents could be identified from a population-based study using an asthma-specific JEM. Application of JEMs can be a useful tool to estimate asthma risks attributable to specific occupational exposures in the general population. However, these specific exposure risks should be interpreted in connection with the whole of concomitant exposures constituting the work environment.

Adult↗

PubMed2004

Nitrogen dioxide is not associated with respiratory infection during the first year of life.

BACKGROUND: Nitrogen dioxide (NO(2)) has been related to respiratory infections in experimental studies but its role remains controversial in general population studies of children. We aim to assess the association between indoor NO(2) and lower respiratory tract infections (LRTI) during the first year of life in a multicentre prospective cohort study. METHODS: Children (n = 1611) were recruited prior to birth for the Asthma Multicentre Infants Cohort Study (AMICS). Three concurrent cohorts (Ashford, Kent [UK]; Barcelona city, and Menorca Island [Spain]) followed the same research protocol. NO(2) was measured with passive diffusion tubes placed in the living room for 2 weeks when infants were approximately 3 months old. Doctor-diagnosed LRTI during the first year of life (as well as antibiotic use) were measured by questionnaire, and in Ashford validated by the examination of clinical records. In Barcelona, direct measurements using nasopharyngeal lavage and cultures within a continuous surveillance system were done. RESULTS: The cumulative rates of LRTI (39% in Ashford, 28% in Barcelona, and 45% in Menorca) were unrelated to NO(2) levels (corresponding medians 6, 46, and 12 ppb, respectively) in all three centres (all odds ratios being around 1). Similarly, the rates of LRTI in Barcelona measured with the continuous record showed no association with NO(2) (all rate ratios being below 1). In addition, there was no association between rate of antibiotics courses per year per child (2.4 in Ashford, 1.7 in Barcelona, 0.9 in Menorca) and NO(2) levels. CONCLUSIONS: Indoor NO(2) at current levels does not seem to be involved in increasing respiratory infections by itself in infants, suggesting that the effects observed in studies on outdoor air are probably due to other copollutants.

Air Pollutants↗