A study of respiratory illnesses in infants and nitrogen dioxide exposure

Feasibility of a birth cohort study dedicated to assessing acute infections using symptom diaries and parental collection of biomaterials

Background

A birth cohort dedicated to studying infections in early childhood may be assisted by parental recording of symptoms on a daily basis and a collection of biomaterials. We aimed at testing the feasibility of this approach for use in a long-term study focusing on infections in children in Germany.

Methods

Parents of 1- to 3-year-old children (n = 75) were recruited in nursery schools. They were asked to complete a symptom diary on a daily basis and to take monthly and symptom-triggered nasal swabs and stool samples from their child over the study period of three months. Feasibility was measured by means of the return proportions of symptom diaries and bio samples; acceptance was assessed by a questionnaire delivered to participants at the end of the study.

Results

The majority of the participants filled in the symptom diary during the three months study for 75 or more days (77.3 %), and provided the monthly nasal swabs (62.7 %) and stool samples (65.3 %). The time needed for the tasks was acceptable for most participants (symptom diary: 92.3 %, nasal swabs: 98.5 %, stool samples: 100.0 %). In 64.3 % of the symptom-triggered nasal swabs, respiratory viruses were found compared to 55.5 % in throat swabs taken by health-care professionals within the “ARE surveillance Lower Saxony”, a special project by the Governmental Institute of Public Health of Lower Saxony to investigate causal pathogens for acute respiratory infections in children.

Conclusions

The parental assessment of symptoms and collection of biomaterials in a birth cohort dedicated to studying infections appears feasible in a middle class German population. The success of the study will depend on the ability to maintain these activities over a long time period.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-1189-0) contains supplementary material, which is available to authorized users.

Indoor air pollution and respiratory function of children in Ashok Vihar, Delhi: an exposure-response study

The objective of this study was to investigate the effects of indoor air pollution on respiratory function of children (aged 7-15 years). The study took place at Ashok Vihar, an urban locality in the northwest part of Delhi during the summer months of June and July 2004. The team did house visits. The questionnaire, administered at the house itself, asked about the history of smoking in the family, type of cooking fuel used, duration of cooking, ventilation and lighting at the cooking place, and other confounders. In total, 441 children (59% male, 41% female) between ages 7 and 15 years were considered for the study, and a detailed profile was collected. Clinical examination with special reference to respiratory system was done. Pulmonary function tests/peak expiratory flow rates of each child were measured. Indoor air pollutant (suspended particulate matter, SO(2), NO(2)) was measured, and the effect of these pollutants on the children's respiratory function was analyzed. The respiratory health profile suggests that children had cough, sputum production, shortness of breath, wheezing, common cold, and throat congestion. Indoor SO(2) , NO(2), and suspended particulate matter levels were high in houses where there was a family history of smoking. SO(2) level was significantly high according to occupancy per room. NO(2) and suspended particulate matter levels were significantly high in houses where children had respiratory problems. It is concluded that indoor air pollution had an association with respiratory function of children.

Airborne endotoxin is associated with respiratory illness in the first 2 years of life

To determine the influence of endotoxin on the incidence of acute respiratory illness during the first 2 years of life, we carried out a longitudinal follow-up study, beginning at birth, of 332 children born in Prince Edward Island, Canada. We measured 5-day averaged air endotoxin in the homes of children, whose parents provided information by daily symptom diaries and twice-monthly telephone contact for up to 2 years. Endotoxin concentration was 0.49 +/- 3.49 EU/m3 (geometric mean +/- geometric SD), and number of annualized illness episodes was 6.83 +/- 2.80 (mean +/- SD). A doubling of the air endotoxin concentration was associated with an increase of 0.32 illness episodes per year (p = 0.0003), adjusted for age, year of study, breast-feeding, environmental tobacco smoke, child care attendance, indoor temperature, and income. Indoor mold surface area and fungal ergosterol were not significantly associated with endotoxin. Airborne endotoxin appears to be a risk factor for clinically symptomatic respiratory illnesses during the first 2 years of life independent of indoor fungus.

The burden of pneumonia in children: an Asian perspective

Pneumonia results in two million deaths each year among children worldwide (20% of all child deaths), 70% of them in Africa and South-east Asia. Most countries in Africa and Asia record 2-10 times more children with pneumonia (7-40/100 annually) than in the USA. Apart from resource constraints and an overburdened health system, there is lack of uniformity in defining pneumonia. Most nations employ a WHO standard case management protocol using age-specific cut-offs for increased respiratory rates and chest in-drawing for a clinical definition of pneumonia. The limited data available on the causative organisms have identified Streptococcus pneumoniae, Haemophilus influenzae and viruses such as respiratory syncytial virus (RSV), influenza, para influenza and adenoviruses as the major pathogens. Measles infection increases pneumonia morbidity and mortality. Low birth weight, under-nutrition, hypovitaminosis A, zinc deficiency, lack of breastfeeding, air pollution (including environmental tobacco smoke) and over-crowding increase the risk for pneumonias in children. Standard case management protocols used for acute respiratory infections (ARIs) in these countries have brought down the disease burden but an improvement in the diagnostic algorithm is needed to appropriately recognise those with associated wheeze. Research is needed to find effective and affordable preventive strategies.

Indoor exposures to air pollutants and allergens in the homes of asthmatic children in inner-city Baltimore

This paper presents indoor air pollutant concentrations and allergen levels collected from the homes of 100 Baltimore city asthmatic children participating in an asthma intervention trial. Particulate matter (PM), NO2, and O3 samples were collected over 72 h in the child's sleeping room. Time-resolved PM was also assessed using a portable direct-reading nephelometer. Dust allergen samples were collected from the child's bedroom, the family room, and the kitchen. The mean PM10 concentration, 56.5+/-40.7 microg/m3, is 25% higher than the PM2.5 concentration (N=90), 45.1+/-37.5 microg/m3. PM concentrations measured using a nephelometer are consistent and highly correlated with gravimetric estimates. Smoking households' average PM2.5 and PM10 concentrations are 33-54 microg/m3 greater than those of nonsmoking houses, with each cigarette smoked adding 1.0 microm/m3 to indoor PM2.5 and PM10 concentrations. Large percentages of NO2 and O3 samples, 25% and 75%, respectively, were below the limit of detection. The mean NO2 indoor concentration is 31.6+/-40.2 ppb, while the mean indoor O3 concentration in the ozone season was 3.3+/-7.7 ppb. The levels of allergens are similar to those found in other inner cities. Results presented in this paper indicate that asthmatic children in Baltimore are exposed to elevated allergens and indoor air pollutants. Understanding this combined insult may help to explain the differential asthma burden between inner-city and non-inner-city children.

Effect of air pollution on pediatric respiratory emergency room visits and hospital admissions

In order to assess the effect of air pollution on pediatric respiratory morbidity, we carried out a time series study using daily levels of PM10, SO2, NO2, ozone, and CO and daily numbers of pediatric respiratory emergency room visits and hospital admissions at the Children's Institute of the University of Sao Paulo Medical School, from August 1996 to August 1997. In this period there were 43,635 hospital emergency room visits, 4534 of which were due to lower respiratory tract disease. The total number of hospital admissions was 6785, 1021 of which were due to lower respiratory tract infectious and/or obstructive diseases. The three health end-points under investigation were the daily number of emergency room visits due to lower respiratory tract diseases, hospital admissions due to pneumonia, and hospital admissions due to asthma or bronchiolitis. Generalized additive Poisson regression models were fitted, controlling for smooth functions of time, temperature and humidity, and an indicator of weekdays. NO2 was positively associated with all outcomes. Interquartile range increases (65.04 microg/m3) in NO2 moving averages were associated with an 18.4% increase (95% confidence interval, 95% CI = 12.5-24.3) in emergency room visits due to lower respiratory tract diseases (4-day moving average), a 17.6% increase (95% CI = 3.3-32.7) in hospital admissions due to pneumonia or bronchopneumonia (3-day moving average), and a 31.4% increase (95% CI = 7.2-55.7) in hospital admissions due to asthma or bronchiolitis (2-day moving average). The study showed that air pollution considerably affects children's respiratory morbidity, deserving attention from the health authorities.

Estimation of occupational and nonoccupational nitrogen dioxide exposure for Korean taxi drivers using a microenvironmental model

Occupational and nonoccupational personal nitrogen dioxide (NO(2)) exposures were measured using passive samplers for 31 taxi drivers in Asan and Chunan, Korea. Exposures were also estimated using a microenvironmental time-weighted average model based on indoor, outdoor and inside the taxi area measurements. Mean NO(2) indoor and outdoor concentrations inside and outside the taxi drivers' houses were 24.7+/-10.7 and 23.3+/-8.3 ppb, respectively, with a mean indoor to outdoor NO(2) ratio of 1.1. Mean personal NO(2) exposure of taxi drivers was 30.3+/-9.7 ppb. Personal NO(2) exposures for drivers were more strongly correlated with interior vehicle NO(2) levels (r = 0.89) rather than indoor residential NO(2) levels (r = 0.74) or outdoor NO(2) levels (r = 0.71). The main source of NO(2) exposure for taxi drivers was considered to be occupational driving. Interestingly, the NO(2) exposures for drivers' using LPG-fueled vehicles (26.3+/-1.3 ppb) were significantly lower than those (38.1+/-1.3 ppb) using diesel-fueled vehicle (P <0.01). Since drivers spent most of their time inside their vehicle and indoors at home, a microenvironmental model was used to estimate the personal NO(2) exposure with indoor and outdoor NO(2) levels of the residence, and interior vehicle NO(2) levels (P <0.001). Some subpopulations, such as professional drivers, might be exposed to high NO(2) levels because they drive diesel-using vehicles outdoors in Korea.

Tendência secular da doença respiratória na infância na cidade de São Paulo (1984-1996)

OBJETIVO: Estimar a prevalência e a distribuição social da doença respiratória na infância, estabelecer a tendência secular dessa enfermidade e analisar sua determinação, com base nos dados coletados por dois inquéritos domiciliares realizados na cidade de São Paulo, SP, em 1984/85 e em 1995/96. MÉTODOS: Os inquéritos estudaram amostras probabilísticas da população residente na cidade com idades entre zero e 59 meses (1.016 em 1984/85 e 1.280 em 1995/96). Nos dois inquéritos estimou-se a prevalência instantânea da doença respiratória alta (acima da epiglote) e da doença respiratória baixa com e sem chiado à ausculta pulmonar. A ocorrência da doença respiratória foi aferida por exames clínicos realizados em dias aleatórios, nos próprios domicílios das crianças, por médicos pediatras devidamente treinados e padronizados quanto ao diagnóstico da doença. Os exames clínicos incluíam a anamnese do dia, antecedentes de doença respiratória e o exame físico completo da criança, incluindo inspeção da orofaringe, otoscopia e ausculta pulmonar. Nos dois inquéritos, os exames foram distribuídos ao longo de um período de cerca de 12 meses, de modo a garantir uma varredura uniforme das várias áreas da cidade ao longo das quatro estações. O estudo da distribuição social da doença respiratória levou em conta tercis da renda familiar per capita em cada um dos inquéritos. A estratégia analítica para estudar os determinantes da evolução da prevalência da doença na população empregou modelos hierárquicos de causalidade, análises multivariadas de regressão e procedimentos análogos aos utilizados para calcular riscos atribuíveis populacionais. RESULTADOS/CONCLUSÕES: Houve entre os inquéritos aumentos expressivos na prevalência instantânea da doença respiratória alta (de 22,2% para 38,8%) e da doença respiratória baixa sem e com chiado (de 6,0% para 10,0% e de 0,8% para 2,8%, respectivamente). No caso da doença alta e da doença baixa sem chiado, o aumento é generalizado nos vários estratos sociais, o que não altera, no período, a situação discretamente menos favorável dos estratos de menor renda. No caso da doença baixa com chiado, o aumento se restringe aos estratos de renda baixa e intermediária, sendo particularmente intenso no estrato de menor renda, o que determina o surgimento de uma forte relação inversa entre a doença e a renda familiar. Mudanças positivas em determinantes distais das doenças respiratórias (renda familiar e escolaridade materna) e em variáveis relacionadas à salubridade das moradias justificariam declínio modesto e não aumento das doenças respiratórias na cidade. O aumento na freqüência a creches, observado no período, poderia contrabalançar o efeito positivo das melhorias em variáveis socioeconômicas e ambientais, mas não seria suficiente para justificar o aumento das doenças respiratórias na cidade.

Indoor air pollution in developing countries and acute lower respiratory infections in children

BACKGROUND

A critical review was conducted of the quantitative literature linking indoor air pollution from household use of biomass fuels with acute respiratory infections in young children, which is focused on, but not confined to, acute lower respiratory infection and pneumonia in children under two years in less developed countries. Biomass in the form of wood, crop residues, and animal dung is used in more than two fifths of the world's households as the principal fuel.

METHODS

Medline and other electronic databases were used, but it was also necessary to secure literature from colleagues in less developed countries where not all publications are yet internationally indexed.

RESULTS

The studies of indoor air pollution from household biomass fuels are reasonably consistent and, as a group, show a strong significant increase in risk for exposed young children compared with those living in households using cleaner fuels or being otherwise less exposed. Not all studies were able to adjust for confounders, but most of those that did so found that strong and significant risks remained.

CONCLUSIONS

It seems that the relative risks are likely to be significant for the exposures considered here. Since acute lower respiratory infection is the chief cause of death in children in less developed countries, and exacts a larger burden of disease than any other disease category for the world population, even small additional risks due to such a ubiquitous exposure as air pollution have important public health implications. In the case of indoor air pollution in households using biomass fuels, the risks also seem to be fairly strong, presumably because of the high daily concentrations of pollutants found in such settings and the large amount of time young children spend with their mothers doing household cooking. Given the large vulnerable populations at risk, there is an urgent need to conduct randomised trials to increase confidence in the cause-effect relationship, to quantify the risk more precisely, to determine the degree of reduction in exposure required to significantly improve health, and to establish the effectiveness of interventions.

Indoor nitrogen dioxide in homes along trunk roads with heavy traffic

OBJECTIVES

To assess the distribution of indoor nitrogen dioxide (NO2) concentrations in homes located in differing environments, and to investigate the influence of factors such as automobile exhaust on the indoor environment.

METHODS

The concentrations of indoor NO2 over 24 hours were measured in both the heating and non-heating periods in homes of pupils from nine elementary schools in Chiba, Japan. Information on factors that could influence indoor environments was collected by questionnaire.

RESULTS

Indoor NO2 concentrations during the heating period were higher in homes with unvented heaters than in homes with vented heaters, although the concentrations varied greatly among homes primarily because of the type of heating device used. During the non-heating period, indoor NO2 concentrations were significantly higher in homes adjacent to trunk roads than in homes located in other areas. Multiple regression analysis showed that indoor NO2 concentrations were associated with atmospheric NO2 in homes with vented heaters during the heating period, and in homes in areas other than on the roadside during the non-heating period. In areas other than the roadside, cigarette smoking in indoor environments also significantly contributed to indoor NO2. The average concentrations of indoor NO2 in the homes of pupils attending each school were significantly related to the atmospheric NO2 in areas other than the roadside. However, the relation between indoor and atmospheric NO2 concentrations was not significant in roadside areas.

CONCLUSIONS

These findings suggest that indoor NO2 concentrations are related to the atmospheric NO2 and type of heating appliances, and are also affected by automobile exhaust in homes located in roadside areas.

Nitrogen dioxide, the oxides of nitrogen, and infants' health symptoms. ALSPAC Study Team. Avon Longitudinal Study of Pregnancy and Childhood

In this cross-sectional postal study, the authors measured nitrogen dioxide levels inside infants' bedrooms and outside their homes. During the 2-wk monitoring period, the authors investigated the association between nitrogen dioxide levels and 20 infant symptoms. The subjects were 1,200 women who had infants aged 3-12 mo. Median levels of indoor and outdoor nitrogen dioxide were 6.8 and 12.6 ppb, respectively. Environmental factors that were associated significantly with indoor levels were gas cooking, cigarette smoking, reported traffic levels, and presence of a kerosene heater; use of a cooker hood was associated negatively with indoor nitrogen dioxide levels. There was no evidence for any short-term significant association between prevalence of respiratory symptoms and nitrogen dioxide levels. Diarrhea, the only symptom associated significantly and positively with indoor nitrogen dioxide levels, had unadjusted and adjusted odds ratios of 1.48 (95% confidence interval: 1.13, 1.95) and 1.38 (1.11, 1.70), respectively. This association is discussed in terms of a proposed mechanism with nitric oxide. No association between a gas cooker in the home and diarrhea was found. The association between diarrhea and nitrogen dioxide level might have been a chance finding; the authors investigated 20 symptoms, and at least 1 was expected to be significant at the .05 level. The finding, however, was similar to that reported in a previous study in which a gas cooker was a proxy for nitrogen dioxide exposure.

Effects of nitrogen dioxide on respiratory tract clearance in the ferret

During growth and development, young children are periodically exposed to relatively high concentrations of various air contaminants, including tobacco smoke and environmental pollutants generated by fossil fuel use. The effects of these exposures on respiratory function and lung development are difficult to determine because of interindividual variation and lack of accurate dosimetry. To provide information on the effects of chronic exposure to a common indoor and outdoor pollutant during lung development, a study was performed to assess the effects of exposure to two concentrations of nitrogen dioxide (NO2; 0.5 or 10 ppm) on tracer particle clearance from the airways of ferrets exposed during postnatal respiratory tract development. Separate groups of ferrets were exposed nose-only to the test atmospheres or clean air 4 h/d, 5 d/wk, for either 8 or 15 wk. Those animals exposed for 8 wk were subsequently housed in a filtered air environment until the particle clearance measurements commenced at 3 wk prior to the end of the 15-wk exposure protocol. Radiolabeled (51Cr) tracer particles were deposited in the respiratory tract of all animals by inhalation, and the clearance rates from the head and thoracic regions were separately monitored for 18 d. No significant effects of the NO2 exposure on head airways clearance were seen. In contrast, the rates of particle clearance from the thorax of both the 8- and 15-wk groups exposed to 10 ppm NO2 were significantly reduced, and did not differ from each other. Thoracic clearance was also reduced in animals exposed to 0.5 ppm, but the rate was not significantly different from that of the clean air exposed controls. These results show that NO2 at moderate concentrations caused highly significant changes in the deep lung of the juvenile ferret, and suggest that impairment of the clearance function may be only slowly recovered after chronic exposure.

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.

Comparability of parent reports of respiratory illnesses with clinical diagnoses in infants

In a cohort study of respiratory illnesses from birth through age 18 months, the investigators assessed the occurrence of illness by telephone reports of respiratory symptoms. To assess the comparability of illness events based on symptom reports with usual clinical modalities, a nurse practitioner examined children during illnesses, and office and clinic records of outpatient visits were reviewed. Respiratory illnesses were defined as symptom episodes of at least 2 days; lower respiratory illnesses included at least 1 day of either wet cough or wheeze. This report is based on 10,771 illnesses in the 1,315 subjects enrolled. Runny or stuffy nose was reported for most (93%) illnesses, wet cough in 33%, and wheeze in 6%. In comparison with the diagnoses made by a nurse practitioner, parent report of wet cough or wheeze was sensitive (93.4%) for detecting lower respiratory illnesses, but nonspecific with specificity of only 24.2%. The majority of the false-positive lower respiratory illnesses had the symptom of wet cough. The comparison of parent reports with outpatient records provided similar findings. Standardized reporting of respiratory illnesses can be achieved with a telephone surveillance system but classification of specific illnesses from the surveillance information may differ from diagnoses made by clinicians.

Effect of chronic exposure to NO2 in the developing ferret lung

The effect of chronic exposure to low (0.5 ppm) and high (10 ppm) concentrations of NO2 on the development of the ferret lung was studied in animals exposed 4 h/day, 5 days/week from age 6 weeks through 20 weeks. Morphometric analysis showed significant changes in alveolar dimensions at both concentrations, compared to air-exposed controls. Thickened alveolar walls, increased cellularity and collagen deposition, increased lung size and the appearance of lesions indicative of oxidant damage indicate that even low concentrations of this gas during lung development may have adverse consequences for adult lung function.