Outdoor air pollution and children's respiratory symptoms in the steel cities of New South Wales

Methodological issues in descriptive environmental epidemiology. The example of study Sentieri

BACKGROUND

Descriptive epidemiology identifies associations between environmental exposures and health effects that require results from methodologically stronger studies before causation can be considered.

OBJECTIVE

To critically review the methodology and results of Sentieri, a descripitive study on residence in areas with one or more industrial source of pollution.

METHODS

We systematically reviewed the literature quoted by Sentieri for the selection of health effects of nine types of pollution sources of a-priori interest. We also reviewed and meta-analyzed the results of the first report of Sentieri, that analyzed mortality in 44 polluted sites (PS), and 17 causes of deaths during 1995-2002.

RESULTS

Among 159 study results quoted by Sentieri, 23.9 % were supportive of an association between residence near a pollution source and a health effect, 30.2 % were partially supportive, 10.7 % were not supportive, and 35.2 % were not relevant. Among 653 standardized mortality ratios for associations between PS-specific pollution sources and causes of death, 14.4% were significantly above 1.02, and 9.0% were significantly below 0.98. Among 48 meta-analysis, seven were significantly above 1.0, including five on exposure to asbestos.

CONCLUSIONS

Sentieri exemplifies the limitations of descriptive environmental epidemiology studies, in which most hypotheses have limited prior support, most results do not show associations, data on potential confounders and other sources of bias are not available. Such studies tend to replicate well-known associations and occasionally can identify critical situations requiring more investigation, but cannot be used to infer causality either in general or in specific circumstances.

The Australian Child Health and Air Pollution Study (ACHAPS): A national population-based cross-sectional study of long-term exposure to outdoor air pollution, asthma, and lung function

Most studies of long-term air pollution exposure and children's respiratory health have been performed in urban locations with moderate pollution levels. We assessed the effect of outdoor nitrogen dioxide (NO₂), as a proxy for urban air pollution, on current asthma and lung function in Australia, a low-pollution setting. We undertook a national population-based cross-sectional study of children aged 7-11 years living in 12 Australian cities. We collected information on asthma symptoms from parents via questionnaire and measured children's lung function (forced expiratory volume in 1 s [FEV₁], forced vital capacity [FVC]) and fractional exhaled nitric oxide [Fe_NO]). We estimated recent NO₂ exposure (last 12 months) using monitors near each child's school, and used a satellite-based land-use regression (LUR) model to estimate NO₂ at each child's school and home. Our analysis comprised 2630 children, among whom the prevalence of current asthma was 14.9%. Mean (±SD) NO₂ exposure was 8.8 ppb (±3.2) and 8.8 ppb (±2.3) for monitor- and LUR-based estimates, respectively. Mean percent predicted post-bronchodilator FEV₁ and FVC were 101.7% (±10.5) and 98.8% (±10.5), respectively. The geometric mean Fe_NO concentration was 9.4 ppb (±7.1). An IQR increase in NO₂ (4.0 ppb) was significantly associated with increased odds of having current asthma; odds ratios (ORs) were 1.24 (95% CI: 1.08, 1.43) and 1.54 (95% CI: 1.26, 1.87) for monitor- and LUR-based estimates, respectively. Increased NO₂ exposure was significantly associated with decreased percent predicted FEV₁ (-1.35 percentage points [95% CI: -2.21, -0.49]) and FVC (-1.19 percentage points [95% CI: -2.04, -0.35], and an increase in Fe_NO of 71% (95% CI: 38%, 112%). Exposure to outdoor NO₂ was associated with adverse respiratory health effects in this population-based sample of Australian children. The relatively low NO₂ levels at which these effects were observed highlight the potential benefits of continuous exposure reduction.

Environment and health in contaminated sites: the case of Taranto, Italy

The National Environmental Remediation programme in Italy includes sites with documented contamination and associated potential health impacts (National Priority Contaminated Sites-NPCSs). SENTIERI Project, an extensive investigation of mortality in 44 NPCSs, considered the area of Taranto, a NPCS where a number of polluting sources are present. Health indicators available at municipality level were analyzed, that is, mortality (2003-2009), mortality time trend (1980-2008), and cancer incidence (2006-2007). In addition, the cohort of individuals living in the area was followed up to evaluate mortality (1998-2008) and morbidity (1998-2010) by district of residence. The results of the study consistently showed excess risks for a number of causes of death in both genders, among them: all causes, all cancers, lung cancer, and cardiovascular and respiratory diseases, both acute and chronic. An increased infant mortality was also observed from the time trends analysis. Mortality/morbidity excesses were detected in residents living in districts near the industrial area, for several disorders including cancer, cardiovascular, and respiratory diseases. These coherent findings from different epidemiological approaches corroborate the need to promptly proceed with environmental cleanup interventions. Most diseases showing an increase in Taranto NPCS have a multifactorial etiology, and preventive measures of proven efficacy (e.g., smoking cessation and cardiovascular risk reduction programs, breast cancer screening) should be planned. The study results and public health actions are to be communicated objectively and transparently so that a climate of confidence and trust between citizens and public institutions is maintained.

Short-term risk of hospitalization for asthma or bronchiolitis in children living near an aluminum smelter

Few studies have measured the effect of short-term exposure to industrial emissions on the respiratory health of children. Here we estimate the risk of hospitalization for asthma and bronchiolitis in young children associated with their recent exposure to emissions from an aluminum smelter. We used a case-crossover design to assess the risk of hospitalization, February 1999-December 2008, in relation to short-term variation in levels of exposure among children 0-4 years old living less than 7.5 km from the smelter. The percentage of hours per day that the residence of a hospitalized child was in the shadow of winds crossing the smelter was used to estimate the effect of wind-borne emissions on case and crossover days. Community-wide pollutant exposure was estimated through daily mean and daily maximum SO2 and PM2.5 concentrations measured at a fixed monitoring site near the smelter. Odds ratios (OR) were estimated using conditional logistic regressions. The risk of same-day hospitalization for asthma or bronchiolitis increased with the percentage of hours in a day that a child's residence was downwind of the smelter. For children aged 2-4 years, the OR was 1.27 (95% CI=1.03-1.56; n=103 hospitalizations), for an interquartile range (IQR) of 21% of hours being downwind. In this age group, the OR with PM2.5 daily mean levels was slightly smaller than with the hours downwind (OR: 1.22 for an IQR of 15.7 μg/m(3), 95% CI=1.03-1.44; n=94 hospitalizations). Trends were observed between hospitalizations and levels of SO2 for children 2-4 years old. Increasing short-term exposure to emissions from a Quebec aluminum smelter was associated with an increased risk of hospitalization for asthma and bronchiolitis in young children who live nearby. Estimating exposure through records of wind direction allows for the integration of exposure to all pollutants carried from the smelter stack.

ECONOMIC BENEFITS OF REDUCING PARTICULATE AND SULFATE EMISSIONS FROM THE CEMENT INDUSTRY IN LEBANON

The cement industry constitutes a major source of air pollution and its environmental impacts have historically raised considerable public concern. This paper presents a health-based economic assessment of reducing particulate and sulfate emissions from a cement industrial complex. The economic valuation of the potential decrease in mortality and morbidity rates due to emissions reduction was conducted using a human capital approach and a cost of illness approach, respectively.

Mechanism of asthmatic exacerbation by ambient air pollution particles

In the previous two to three decades, the prevalence of asthma has risen in numerous countries of the world. Correlating with this elevated prevalence of asthma, societies have observed increased air pollution from specific sources. Studies have implicated certain pollutants in asthmatic exacerbation. Particulate matter (PM) is the pollutant most frequently identified with worsening of this airway disease. PM is a temporally and spatially shifting suspension of solids and liquids originating from both natural and anthropogenic sources. Exposures to elevated levels of PM have been associated with asthmatic exacerbations by employing a diverse array of end points, including respiratory symptoms, use of medication, medical visits, emergency room visits, hospital admissions and pulmonary function decrements. Pertinent to worsening of asthma by ambient air PM, there are other particle-associated exposures that similarly precipitate asthmatic exacerbations. These include traffic-associated pollutants, diesel exhaust, emissions from gas and wood stoves, burning of biomass and environmental tobacco smoke. It is widely accepted that the biological effects exerted by all particle exposures result from oxidative stress. This stimulates cell signaling, transcription factor activation and mediator release in the respiratory tract, culminating in inflammation. Other postulated mechanisms for asthmatic exacerbation following PM exposure include an impact on the incidence of infections and adjuvant effects.

Air quality and chronic disease: why action on climate change is also good for health

There is increasing evidence that air pollution contributes to the burden of chronic disease and premature mortality, particularly from cardiovascular and respiratory causes. Action now urgently required to mitigate climate change has the potential co-benefit of improving air quality and reducing the chronic disease burden. Fossil fuel combustion, primarily from motor vehicles and energy generation, is a major contributor to anthropogenic climate change and air pollution-related health conditions. Action to reduce greenhouse gas emissions by improving energy efficiency, departing from carbon-intensive energy generation, facilitating mass transit and active transport options, also has the potential for significant public health benefits.

Industrial air pollution and children's respiratory health: a natural experiment in Călăraşi

BACKGROUND

In 1993-1997, we described a high incidence of wheezing in children living near the iron, steel, and coke factory of Călăraşi (Romania). In 1998, the factory was closed.

OBJECTIVE

To investigate the influence of closing the factory on the incidence of wheezing in children living near the factory.

METHODS

We used this natural experiment to compare wheezing occurrence in children below age 2 in an area near the factory and in a village 10 km from the factory (Roseţi). We studied three birth cohorts: those 2 years old before the closing of the factory (group 1), those born before the closing and returning 2 after the closing (group 2), those born after the closing (group 3).

RESULTS

The relative risk (95% CI) of having at least one episode of wheezing during the first life-year was 0.51 (0.30-0.85) in group 3 versus group 1, and 0.95 (0.64-1.40) for group 2 versus group 1. After adjusting for possible confounders, the incidence dropped in Călăraşi (odds ratio [OR] 0.38, 95% CI 0.19-0.76), while it increased in Roseţi (OR 8.36, 95% CI 1.84-38.0). Results for the 2-year incidence were similar.

CONCLUSION

Industrial air pollution by the factory was the main risk factor for wheezing during the first life-years of the children of Călăraşi. Closing the factory resulted in a significant decrease in wheezing incidence rates, which still remained higher than in a nearby village.

Air pollution: a threat to the health of our children

BACKGROUND/METHODS

Current air pollution levels pose a threat to the health of children starting from conception. The scientific evidence is presented for mortality, morbidity, and sub-clinical effects. The first section deals with exposure data, the following sections with the evidence of health effects from epidemiology and toxicology leading to recommendations.

RESULTS

Improved air quality reduces the number of infants' deaths as well as disease and pain.

CONCLUSIONS

Medical doctors have a responsibility to know the facts and to advise their patients. Doctors when visiting their patients' homes should be aware of the possibly grave impact of the indoor environment for the respiratory health of their patients. They should recognize and advise the parents on problems associated with environmental tobacco smoke, poor ventilation, mould growth, and maintenance of heating installations. With regard to outdoor air pollution, doctors could serve as role models and also advise their patients and parents on environmentally friendly behaviour. Such behaviour not only calls for personal commitment but also for the right infrastructure to be provided (e.g. public transport, district heating). Doctors should be proactive in the community and in their country as advocates for a healthier environment for our children.

Prevalence of respiratory symptoms in children and air quality by village in rural Indonesia

AIM

This study compared prevalence of respiratory symptoms in three Indonesian villages and related this to air quality.

METHODS

We interviewed caregivers of 382 children, using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire, and monitored air quality during the survey period.

RESULTS

Respiratory symptom prevalence was highest in Kerinci (40.5%), followed by SP7 (33.3%) and Pelalawan (19.8%). Compared with Pelalawan, adjusted odds ratios were 3.17 (95% confidence interval, 1.43-7.07) for Kerinci, and 2.03 (1.04-3.96) for SP7. Ambient air quality levels were highest in Kerinci for PM10 and hydrocarbon (means: 102.9 microg/m3, 10.5 microg/m3), followed by SP7 (73.7 microg/m3, 6.3 microg/m3) and Pelalawan (26.1 microg/m3, 4.7 microg/m3).

CONCLUSIONS

The higher prevalence of respiratory symptoms in Kerinci and SP7 could be the result of higher PM10 and hydrocarbon levels in these locations.

Symptoms of asthma: comparison of a parent-completed retrospective questionnaire with a prospective daily symptom diary

In a study of the effects of indoor air pollution on the respiratory health of children in Newcastle, Australia, parental reports of symptoms experienced by children over the previous 12 months were compared with a prospective record of symptoms of cough and wheeze. Parents of 390 children aged 8-11 years completed a questionnaire about child and family respiratory health, which was used to assign children to one of four symptom groups: Wheeze (two or more attacks of wheezing in the last 12 months), Chest-Colds (two or more chest-colds in the last 12 months without wheezing), Cough Alone (a dry cough at night, without a cold or chest infection, that lasted for more than 2 weeks), or Control (none). A balanced sample of children (n=139) was invited to participate further by completing lung function tests, atopy testing, and keeping a daily diary of peak expiratory flow (PEF) and symptoms of cough and wheeze over a 7-week period. Valid data for the daily diary were provided by 66/85 (77.6%) of participants who commenced this stage (47.5% of the 139 invited to participate). The Wheeze group reported significantly more subsequent wheeze (median 16.8% of days) than the other three groups (median 0% of days). Parent reports of asthma-like symptoms over the previous 12 months were consistent with the subsequent experience of symptoms recorded in a daily diary.

Airway eosinophilia is associated with wheeze but is uncommon in children with persistent cough and frequent chest colds

The role of eosinophilic airway inflammation in the variant asthma syndromes of cough and chest colds is not well defined. We tested the hypothesis that children with persistent cough and chest colds have increased sputum eosinophils, similar to those with wheeze. The parents of 390 primary school children completed a symptoms questionnaire. Children with wheeze (n = 28), cough (n = 12), recurrent chest colds (n = 17), and no symptoms (control subjects, n = 26), underwent allergy skin prick tests, spirometry, hypertonic saline inhalation challenge, and sputum induction, and then completed a peak expiratory flow (PEF) and symptoms diary over a 2-mo period. Children with wheeze had significantly reduced PEF (p = 0.001) and higher sputum eosinophils when compared with the cough, chest cold, and control groups (3.1% versus 0.5%, 0%, 0%; p = 0.03). The prevalence of eosinophilic bronchitis (sputum eosinophils > 2.5%) was 45% in the wheeze group, which was significantly higher than the control group (9.35%, p = 0.04). Eosinophilic bronchitis was present in two children with cough (20%) and two with chest colds (15%, p > 0.05 versus control). In these groups, eosinophilic bronchitis was not associated with airway hyperresponsiveness (AHR) to hypertonic saline (p > 0.05). Children with cough and chest colds reported greater exposure to environmental tobacco smoke. In conclusion, this community-based survey of children with chronic respiratory symptoms has shown that wheeze is a good discriminator for the presence of eosinophilic bronchitis, and that persistent cough and recurrent chest colds without wheeze should not be considered a variant of asthma. Eosinophilic bronchitis did occur in a significant minority of these "variant asthma" syndromes.

Acute asthma exacerbations and air pollutants in children living in Belfast, Northern Ireland

The incidence of childhood asthma, a common condition, is on the rise worldwide. Despite reductions in the emission of urban smoke, traffic pollution is now a major worldwide problem. Belfast, Northern Ireland, is an old industrial city with major pollution problems. In this study, the authors investigated the rates of acute asthma admissions to Belfast's major children's emergency department. The admissions were studied, relative to day-to-day fluctuations in thoracic particulate matter, sulfur dioxide, nitrogen dioxide, nitric oxide, oxides of nitrogen, ozone, carbon monoxide, benzene, temperature, and rainfall. Daily admissions for acute asthma at the emergency department of the Royal Belfast Hospital and average daily pollution were recorded for the 3-yr period between January 1, 1993, and December 31, 1995. The authors used Poisson regression to assess independent association(s). Individually, small associations were seen for thoracic particulate matter (relative risk = 1.10), sulfur dioxide (relative risk = 1.09), nitrogen dioxide (relative risk = 1.11), nitric oxide (relative risk = 1.07), oxides of nitrogen (relative risk = 1.10), carbon monoxide (relative risk = 1.07), and benzene (1.14); no associations were noted between meteorological factors (temperature and rainfall) or ozone and asthma emergency-department admissions. The authors adjusted for the aforementioned parameters, and benzene level was the only variable associated independently with asthma emergency-department admissions in children. Benzene may be a more reliable method of measuring exposure to vehicle exhaust emissions than measurements of other pollutants.

Fever without apparent source on clinical examination, lower respiratory infections in children, and enterovirus infections

This section focuses on issues in infectious disease that are commonly encountered in pediatric office practice. McCarthy discusses recent literature regarding the evaluation and management of acute fevers without apparent source on clinical examination in infants and children and the evaluation of children with prolonged fevers of unknown origin. Klig reviews recent literature about lower respiratory tract infection in children. Finally, Kennedy and Kahn discuss recent developments in infectious diseases pertinent to office practice.