The association of ambient air pollution with twice daily peak expiratory flow rate measurements in children

A Review of Artificial Neural Network Models Applied to Predict Indoor Air Quality in Schools

BACKGROUND

Indoor air quality (IAQ) in schools can affect the performance and health of occupants, especially young children. Increased public attention on IAQ during the COVID-19 pandemic and bushfires have boosted the development and application of data-driven models, such as artificial neural networks (ANNs) that can be used to predict levels of pollutants and indoor exposures.

METHODS

This review summarises the types and sources of indoor air pollutants (IAP) and the indicators of IAQ. This is followed by a systematic evaluation of ANNs as predictive models of IAQ in schools, including predictive neural network algorithms and modelling processes. The methods for article selection and inclusion followed a systematic, four-step process: identification, screening, eligibility, and inclusion.

RESULTS

After screening and selection, nine predictive papers were included in this review. Traditional ANNs were used most frequently, while recurrent neural networks (RNNs) models analysed time-series issues such as IAQ better. Meanwhile, current prediction research mainly focused on using indoor PM2.5 and CO2 concentrations as output variables in schools and did not cover common air pollutants. Although studies have highlighted the impact of school building parameters and occupancy parameters on IAQ, it is difficult to incorporate them in predictive models.

CONCLUSIONS

This review presents the current state of IAQ predictive models and identifies the limitations and future research directions for schools.

Reductions in particulate matter concentrations resulting from air filtration: A randomized sham-controlled crossover study

One-hundred seventy-two households were recruited from regions with high outdoor air pollution (Fresno and Riverside, CA) to participate in a randomized, sham-controlled, cross-over study to determine the effectiveness of high-efficiency air filtration to reduce indoor particle exposures. In 129 households, stand-alone HEPA air cleaners were placed in a bedroom and in the main living area. In 43 households, high-efficiency MERV 16 filters were installed in central forced-air heating and cooling systems and the participating households were asked to run the system on a clean-air cycle for 15 min per hour. Participating households that completed the study received true air filtration for a year and sham air filtration for a year. Air pollution samples were collected at approximately 6-month intervals, with two measurements in each of the sham and true filtration periods. One week indoor and outdoor time-integrated samples were collected for measurement of PM2.5 , PM10 , and ultrafine particulate matter (UFP) measured as PM0.2 . Reflectance measurements were also made on the PM2.5 filters to estimate black carbon. True filtration significantly improved indoor air quality, with a 48% reduction in the geometric mean indoor PM0.2 and PM2.5 concentrations, and a 31% reduction in PM10 . Geometric mean concentrations of indoor/outdoor reflectance values, indicating fraction of particles of outdoor origin remaining indoors, decreased by 77%. Improvements in particle concentrations were greater with continuously operating stand-alone air cleaners than with intermittent central system filtration. Keeping windows closed and increased utilization of the filtration systems further improved indoor air quality.

Acute and 28-Day Repeated Inhalation Toxicity Study of Glycolic Acid in Male Sprague-Dawley Rats

BACKGROUND/AIM

The use of glycolic acid is present in a variety of consumer products, including medicines, cleaners, cosmetics, and paint strippers. It has recently led to concerns about toxicity from inhalation exposure. Herein, the pulmonary toxicity of glycolic acid was investigated in rats.

MATERIALS AND METHODS

We conducted acute (~458 mg/m³) and sub-acute (~49.5 mg/m³) inhalation tests to identify the potential toxicities of glycolic acid.

RESULTS

Inhalation exposure to glycolic acid in the acute and subacute inhalation tests did not cause any specific changes in clinical examinations, including body weight, organ weight, hematology, serum biochemistry, and histopathology. The polymorphonuclear neutrophils (PMNs) and inflammatory cytokines in Bronchoalveolar lavage fluid (BALF) increased in rats exposed to single and repeated inhalations. In the sub-acute test, the changes induced by glycolic acid were minor or returned to normal during the recovery period.

CONCLUSION

The No Observed Adverse Effect Concentration (NOAEC) for the nasal and pulmonary toxicity of glycolic acid was determined to be over 50 mg/m³ at the end of a 28-day inhalation test in male rats.

The global DNA and RNA methylation and their reversal in lung under different concentration exposure of ambient air particulate matter in mice

Particulate matter (PM) in air pollution is a pervasive risk factor in pulmonary diseases that are always associated with gene expression level alterations in many specific-genes. DNA methylation (5-methylcytosine [5mC]) and RNA methylation (N6-methyladenine [6 mA]) influence the gene expression from transcription and post-transcription level, and the DNA hydroxymethylation (5-hydroxymethylcytosine [5hmC]) is the oxidized form of 5mC. In the present study, the levels of global 5mC, 5hmC and 6 mA of lungs in experimental mice were investigated. We divided the animals into 3 groups randomly, the group 1 was exposed to heavy PM for 24 h in the unfiltered chamber, the group 2 was exposed to filtered air in the filtered chamber, and the group 3 was 10 of the mice in the group 1 after 24 h exposure and then being moved to the filtered chamber for further 120 h exposure. The morphology of lungs showed that acute PM exposure impaired the structure of pulmonary alveolus. Meanwhile, the global level of DNA methylation was decreased, and DNA hydroxymethylation and RNA methylation levels were increased in lungs after PM exposure for only 24 h. Very notably, after being exposed in purified air for 120 h, the pulmonary morphology, the global levels of DNA methylation, DNA hydroxymethylation and RNA methylation of lungs were all reversed. The present study clearly demonstrated the alteration of DNA and RNA methylation after acute heavy PM exposure and emphasized the reversal of the symptoms caused by PM exposure after the air purification, which provided us a new idea for the intervention of the adverse health effects from air pollution. CAPSULE: Acute PM exposure resulted in reduced global DNA methylation and increased global DNA hydroxymethylcytosine and RNA methylation, and air purification reversed these alterations.

A panel study of airborne particulate matter composition versus concentration: Potential for inflammatory response and impaired pulmonary function in children

BACKGROUND

The relationship between airborne particulate matter (PM) and pulmonary function in children has not been consistent among studies, potentially owing to differences in the inflammatory response to PM, based on PM types and sources. The objective of this study was to investigate the effect of airborne PM on pulmonary function in schoolchildren and its potential for an inflammatory response.

METHODS

Daily morning peak expiratory flow (PEF) was measured in 339 schoolchildren in February 2015. Interleukin (IL)-8 production was assessed in THP1 cells stimulated by airborne PM collected every day during the study period, and these IL-8 concentrations are described as the daily IL-8 levels. A linear mixed model was used to estimate the association between PEF values and the daily levels of suspended PM (SPM), PM diameters smaller than 2.5 μm (PM_2.5), and IL-8.

RESULTS

The daily IL-8 levels were significantly associated with those of SPM and PM_2.5. A 0.83 μg/mL increase in IL-8 levels was significantly associated with a -1.07 L/min (95% confidence interval, -2.05 to -0.08) decrease in PEF. A 12.0 μg/m³ increase in SPM and a 10.0 μg/m³ increase in PM_2.5 were associated with a -1.36 L/min (-2.93 to 0.22) and -1.72 L/min (-3.82 to 0.36) decreases in PEF, respectively. There were no significant relationships between PEF, SPM, and PM_2.5.

CONCLUSIONS

These findings suggest that the effects of airborne PM on pulmonary function in schoolchildren might depend more on the pro-inflammatory response than the mass concentration of the PM.

Lifetime Exposure to Ambient Pollution and Lung Function in Children

RATIONALE

Few studies have examined associations between exposure to air pollution and childhood lung function after implementation of strict air quality regulations in the 1990s.

OBJECTIVES

To assess traffic-related pollution exposure and childhood lung function.

METHODS

We geocoded addresses for 614 mother-child pairs enrolled during pregnancy in the Boston area 1999-2002 and followed them until a mid-childhood visit (median age, 7.7). We calculated the proximity of the home to the nearest major roadway. We estimated first year of life, lifetime, and prior-year exposure to particulate matter with a diameter smaller than 2.5 μm (PM2.5) by a hybrid model using satellite-derived aerosol optical depth, and to black carbon (BC) by a land-use regression model.

MEASUREMENTS AND MAIN RESULTS

Residential proximity to roadway and prior-year and lifetime PM2.5 and BC exposure were all associated with lower FVC. Associations with FEV1 were also negative and proportionally similar. Pollution exposures were not associated with the FEV1/FVC ratio or bronchodilator response. Compared with distances greater than or equal to 400 m, living less than 100 m from a major roadway was associated with lower FVC (-98.6 ml; -176.3 to -21.0). Each 2 μg/m(3) increment in prior-year PM2.5 was associated with lower FVC (-21.8 ml; -43.9 to 0.2) and higher odds of FEV1 less than 80% predicted (1.41; 1.03-1.93). Each 0.2 μg/m(3) increment in prior-year BC was associated with a 38.9 ml (-70.4 to -7.3) lower FVC.

CONCLUSIONS

Estimates of long-term exposure to ambient pollution, including proximity to major roadway, PM2.5, and BC (a traffic-related PM2.5 constituent), were associated with lower lung function in this Boston-area cohort of children with relatively low pollution exposures.

Variation in the Effect of Particulate Matter on Pulmonary Function in Schoolchildren in Western Japan and Its Relation with Interleukin-8

This study aimed to investigate the effects of particulate matter (PM) on pulmonary function in schoolchildren, as well as the relationships of these effects with interleukin-8. Morning peak expiratory flow (PEF) was measured daily in 399 children during April-May 2012, and in 384 of these children during March-May 2013. PEF's association with the daily levels of suspended particulate matter (SPM) and PM < 2.5 mm (PM2.5) was estimated using a linear mixed model. Interleukin-8 promoter activity was assessed in THP-G8 cells stimulated by fallen PM collected at Tottori University Hospital during four periods (two in 2012 and two in 2013). An increase of 14.0 mg/m³ in SPM led to PEF changes of -2.16 L/min in 2012 and -0.81 L/min in 2013, respectively. An increment of 10.7 mg/m³ in PM2.5 was associated with PEF changes of -2.58 L/min in 2012 and -0.55 L/min in 2013, respectively. These associations were only significant in 2012. Interleukin-8 promoter activity was significantly higher in both periods of 2012 than in 2013. There was a significant association between pulmonary function in schoolchildren and daily levels of SPM and PM2.5, but this association may differ depending on the PM's ability to elicit interleukin-8 production.

Acidic environment augments FcεRI-mediated production of IL-6 and IL-13 in mast cells

Although blood pH is maintained in a narrow range of around pH 7.4 in living organisms, inflammatory loci are characterized by acidic conditions. Mast cells tend to reside close to the surface of the body in areas such as the mucosa and skin where they may be exposed to exogenous acids, and they play an important role in immune responses. However, little is known about the effects of extracellular acidification on the functions of mast cell. Here, we found that extracellular acidification increased the dinitrophenyl-conjugated human serum albumin (DNP-HSA)-induced production of interleukin (IL)-6 and IL-13 in MC/9 cells or bone marrow-derived mouse mast cells sensitized with anti-DNP IgE. Extracellular acidification also inhibited migration of MC/9 cells toward DNP-HSA. In addition, acidic pH stimulated antigen-induced activation of p38 mitogen-activated protein kinase (MAPK) and protein kinase B (Akt). These findings suggest that extracellular acidification augmented antigen/IgE-induced and FcεRI-mediated production of IL-6 and IL-13 in mast cells, and that this was associated with the enhancement of p38 MAPK and Akt activation.

Longitudinal effects of air pollution on exhaled nitric oxide: the Children's Health Study

OBJECTIVES

To assess the effects of long-term variations in ambient air pollutants on longitudinal changes in exhaled nitric oxide (FeNO), a potentially useful biomarker of eosinophilic airway inflammation, based on data from the southern California Children's Health Study.

METHODS

Based on a cohort of 1211 schoolchildren from eight Southern California communities with FeNO measurements in 2006-2007 and 2007-2008, regression models adjusted for short-term effects of air pollution were fitted to assess the association between changes in annual long-term exposures and changes in FeNO.

RESULTS

Increases in annual average concentrations of 24-h average NO2 and PM2.5 (scaled to the IQR of 1.8 ppb and 2.4 μg/m(3), respectively) were associated with a 2.29 ppb (CI 0.36 to 4.21; p=0.02) and a 4.94 ppb (CI 1.44 to 8.47; p=0.005) increase in FeNO, respectively, after adjustments for short-term effects of the respective pollutants. In contrast, changes in annual averages of PM10 and O3 were not significantly associated with changes in FeNO. These findings did not differ significantly by asthma status.

CONCLUSIONS

Changes in annual average exposure to current levels of ambient air pollutants are significantly associated with changes in FeNO levels in children, independent of short-term exposures and asthma status. Use of this biomarker in population-based epidemiological research has great potential for assessing the impact of changing real world mixtures of ambient air pollutants on children's respiratory health.

Variations in peak expiratory flow measurements associated to air pollution and allergic sensitization in children in Sao Paulo, Brazil

BACKGROUND

In the last 20 years, there has been an increase in the incidence of allergic respiratory diseases worldwide and exposure to air pollution has been discussed as one of the factors associated with this increase. The objective of this study was to investigate the effects of air pollution on peak expiratory flow (PEF) and FEV1 in children with and without allergic sensitization.

METHODS

Ninety-six children were followed from April to July, 2004 with spirometry measurements. They were tested for allergic sensitization (IgE, skin prick test, eosinophilia) and asked about allergic symptoms. Air pollution, temperature, and relative humidity data were available.

RESULTS

Decrements in PEF were observed with previous 24-hr average exposure to air pollution, as well as with 3-10-day average exposure and were associated mainly with PM(10), NO(2), and O(3) in all three categories of allergic sensitization. Even though allergic sensitized children tended to present larger decrements in the PEF measurements they were not statistically different from the non-allergic sensitized. Decrements in FEV1 were observed mainly with previous 24-hr average exposure and 3-day moving average.

CONCLUSIONS

Decrements in PEF associated with air pollution were observed in children independent from their allergic sensitization status. Their daily exposure to air pollution can be responsible for a chronic inflammatory process that might impair their lung growth and later their lung function in adulthood.

Active and uncontrolled asthma among children exposed to air stack emissions of sulphur dioxide from petroleum refineries in Montreal, Quebec: a cross-sectional study

BACKGROUND

Little attention has been devoted to the effects on children's respiratory health of exposure to sulphur dioxide (SO2) in ambient air from local industrial emissions. Most studies on the effects of SO(2) have assessed its impact as part of the regional ambient air pollutant mix.

OBJECTIVE

To examine the association between exposure to stack emissions of SO(2) from petroleum refineries located in Montreal's (Quebec) east-end industrial complex and the prevalence of active asthma and poor asthma control among children living nearby.

METHODS

The present cross-sectional study used data from a respiratory health survey of Montreal children six months to 12 years of age conducted in 2006. Of 7964 eligible households that completed the survey, 842 children between six months and 12 years of age lived in an area impacted by refinery emissions. Ambient SO(2) exposure levels were estimated using dispersion modelling. Log-binomial regression models were used to estimate crude and adjusted prevalence ratios (PRs) and 95% CIs for the association between yearly school and residential SO(2) exposure estimates and asthma outcomes. Adjustments were made for child's age, sex, parental history of atopy and tobacco smoke exposure at home.

RESULTS

The adjusted PR for the association between active asthma and SO(2) levels was 1.14 (95% CI 0.94 to 1.39) per interquartile range increase in modelled annual SO(2). The effect on poor asthma control was greater (PR=1.39 per interquartile range increase in modelled SO(2) [95% CI 1.00 to 1.94]).

CONCLUSIONS

Results of the present study suggest a relationship between exposure to refinery stack emissions of SO(2) and the prevalence of active and poor asthma control in children who live and attend school in proximity to refineries.

Effects of air pollution on respiratory parameters during the wheat-residue burning in Patiala

Effects of pollution produced by wheat-residue burning on respiratory parameters of healthy inhabitants were investigated for two consecutive wheat cultivation periods (February-July in 2007 and 2008) at Patiala city of Punjab, India. A total of 51 selected subjects of the age group 13-53 were selected from five sites of Patiala for pulmonary function tests (PFTs), including force vital capacity (FVC), force expiratory volume in one second (FEV(1)), peak expiratory flow (PEF) and force expiratory flow between 25 to 75% of FVC (FEF(25-75%)) using a spirometer. High volume samplers (HVS) and an Andersen cascade impactor were also used to measure the concentration of suspended particulate matter (SPM) and particulate matter (PM) of size less than 10 mum. PFTs show significant decrease and particulate matter shows a significant increase during the burning period of wheat residue. Decrease in FVC and FEV(1) did not recover even after completion of the exhaustive burning period this is a more serious concern then PEF and FEF(25-75%). The results showed that the public exposure to relatively high levels of pollutants during the exhaustive burning period of wheat residue influences the PFTs of even healthy inhabitants.

Critical considerations in evaluating scientific evidence of health effects of ambient ozone: a conference report

The U.S. Environmental Protection Agency (EPA), under the authority of the Clean Air Act (CAA), is required to promulgate National Ambient Air Quality Standards (NAAQSs) for criteria air pollutants, including ozone. Each NAAQS includes a primary health-based standard and a secondary or welfare-based standard. This paper considers only the science used for revision of the primary standard for ozone in 2008. This paper summarizes deliberations of a small group of scientists who met in June 2007 to review the scientific information informing the EPA Administrator's proposed revision of the 1997 standard. The Panel recognized that there is no scientific methodology that, in the absence of judgment, can define the precise numerical level, related averaging time, and statistical form of the NAAQS. The selection of these elements of the NAAQS involves policy judgments that should be informed by scientific information and analyses. Thus, the Panel members did not feel it appropriate to offer either their individual or collective judgment on the specific numerical level of the NAAQS for ozone. The Panel deliberations focused on the scientific data available on the health effects of exposure to ambient concentrations of ozone, controlled ozone exposure studies with human volunteers, long-term epidemiological studies, time- series epidemiological studies, human panel studies, and toxicological investigations. The deliberations also dealt with the issue of background levels of ozone of nonanthropogenic origin and issues involved with conducting formal risk assessments of the health impacts of current and prospective levels of ambient ozone. The scientific issues that were central to the EPA Administrator's 2008 revision of the NAAQS for ozone will undoubtedly also be critical to the next review of the ozone standard. That review should begin very soon if it is to be completed within the 5-year cycle specified in the CAA. It is hoped that this Report will stimulate discussion of these scientific issues, conduct of additional research, and conduct of new analyses that will provide an improved scientific basis for the policy judgment that will have to be made by a future EPA Administrator in considering potential revision of the ozone standard.

Acute respiratory health effects of air pollution on children with asthma in US inner cities

BACKGROUND

Children with asthma in inner-city communities may be particularly vulnerable to adverse effects of air pollution because of their airways disease and exposure to relatively high levels of motor vehicle emissions.

OBJECTIVE

To investigate the association between fluctuations in outdoor air pollution and asthma morbidity among inner-city children with asthma.

METHODS

We analyzed data from 861 children with persistent asthma in 7 US urban communities who performed 2-week periods of twice-daily pulmonary function testing every 6 months for 2 years. Asthma symptom data were collected every 2 months. Daily pollution measurements were obtained from the Aerometric Information Retrieval System. The relationship of lung function and symptoms to fluctuations in pollutant concentrations was examined by using mixed models.

RESULTS

Almost all pollutant concentrations measured were below the National Ambient Air Quality Standards. In single-pollutant models, higher 5-day average concentrations of NO2, sulfur dioxide, and particles smaller than 2.5 microm were associated with significantly lower pulmonary function. Higher pollutant levels were independently associated with reduced lung function in a 3-pollutant model. Higher concentrations of NO2 and particles smaller than 2.5 microm were associated with asthma-related missed school days, and higher NO2 concentrations were associated with asthma symptoms.

CONCLUSION

Among inner-city children with asthma, short-term increases in air pollutant concentrations below the National Ambient Air Quality Standards were associated with adverse respiratory health effects. The associations with NO2 suggest that motor vehicle emissions may be causing excess morbidity in this population.

Circulating neutrophil CD14 expression and the inverse association of ambient particulate matter on lung function in asthmatic children

BACKGROUND

Identifying baseline inflammatory biomarkers that predict susceptibility to size-specific particulate matter (PM) independent of gaseous pollutants could help us better identify asthmatic subpopulations at increased risk for the adverse health effects of PM.

OBJECTIVE

To evaluate whether the association between lung function and exposure to ambient levels of PM less than 2.5 microm in diameter (PM2.5) (fine) and 10 to 2.5 microm in diameter (PM(10-2.5)) (coarse) in children with persistent asthma differed across baseline measures of inflammation and innate immune activation.

METHODS

We performed a panel study on a local population of 16 children with persistent asthma and evaluated daily pulmonary function (percentage of predicted peak expiratory flow and forced expiratory volume in 1 second) while concurrently measuring daily PM2.5 and PM(10-2.5) exposure from a central site in Chapel Hill, North Carolina. The children underwent a baseline medical evaluation that included assessment of several immunoinflammatory biomarkers in peripheral blood.

RESULTS

Children without measurable CD14 expression on circulating neutrophils had significantly reduced pulmonary function (forced expiratory volume in 1 second and peak expiratory flow) with each interquartile range (IQR) increase in PM2.5 (IQR = 8.5 microg/m3) and PM(10-2.5) (IQR = 4.1 microg/m3) concentration, unlike children with measurable CD14 expression (P < .001 for interaction).

CONCLUSIONS

Asthmatic children with muted surface expression of CD14 on circulating neutrophils may have a decreased capacity to respond to bacterial components of PM.

Fine particles, a major threat to children

BACKGROUND

There is a growing body of evidence for serious health consequences of exposure to ambient air pollution. The general question of who is susceptible is one of the most important gaps in current knowledge regarding particulate matter (PM)-related health effects. Who is susceptible depends on the specific health endpoint being evaluated and the level and length of exposure. Here, we restrict the review on the impact of fine particle exposure on children's health to the following outcomes: infant death, lung function, respiratory symptoms and reproductive outcomes.

METHODS

This is a strategic review of children's susceptibility to ambient fine particles and characteristics of infant and children which underlie their increased susceptibility to PM.

RESULTS

Ambient fine PM is associated with intra-uterine growth retardation, infant mortality; it is associated with impaired lung function and increased respiratory symptoms, particularly in asthmatics. Concerning infant mortality, exposure to PM is strongly and consistently associated with postneonatal respiratory mortality and less consistently with sudden infant death syndrome. Although most of the studies reported adverse effects for this health outcome, the evidence is weaker than for infant death. Exposure to fine PM has been associated with impaired lung function and lung function growth. Most of the studies reported increased prevalence of symptom with increased exposure to fine PM.

CONCLUSION

Fine PM is a major threat to children, because of their higher exposure to PM compared to adults, the immature state of the lung in childhood and also of the immune function at birth. The first months of life might be a period of particular sensitivity. Although the mechanisms of air pollution effects have not yet been completely understood, pregnant women, infants and children need specific protection against exposure to fine particles.

Effects of winter air pollution on pulmonary function of school children in Shenyang, China

To assess the effects of air pollution associated with coal heating in winter on pulmonary function of school children, pulmonary function tests (FVC, FEV(1.0), PEF, FEF(75)) of 332 children in Shenyang, located in the northeast of China, were done four times between October 2001 and June 2002. The collected airborne particulate matter (PM) was analyzed for the concentrations of total suspended particles (TSP), PM of less than 7 microm in aerodynamic diameter (PM(7)), and PM of less than 2.1 microm (PM(2.1)). All four pulmonary function tests were completed in 244 school children. The airborne PM concentration was higher in April 2002 (end of heating) than in October 2001 (prior to heating). All four pulmonary function indices, adjusted for age and height, were significantly lower in April 2002 than in October 2001; the FEV(1.0) was lower in boys (0.233l, 95% CI: 0.167-0.299l) and girls (0.222l, 95% CI: 0.165-0.280l). The decrease continued to be significant in June 2002 compared to October 2001. The decreases in FEV and FEV(1.0) were also significantly associated with airborne PM concentration, which had a delayed effect on pulmonary function. An increase from the 25th to the 75th percentile of TSP, PM(7) and PM(2.1) was associated with a delayed decrease in FEV(1.0); 0.059l (95% CI: 0.020-0.106l), 0.095l (95% CI: 0.057-0.139l) and 0.110l (95% CI: 0.072-0.147l) in boys, and 0.066l (95% CI: 0.026-0.106l), 0.101l (95% CI: 0.063-0.139l) and 0.114l (95% CI: 0.080-0.152l) in girls, respectively. Our findings show that airborne PM might have a subacute effect on pulmonary function in children in Shenyang, and that PM(7) and PM(2.1) have more adverse effects on pulmonary function than TSP. The effects of airborne PM appear to be prolonged.

Chemical composition of atmospheric aerosol (PM10) at a semi-arid urban site: influence of terrestrial sources

Atmospheric aerosol (PM(10)) measurements were made at a regional representative semi-arid urban site, Tirupati, India over one-year period i.e. from October, 2001 to September, 2002. The samples were collected on polyflex filters, and analyzed for the major water-soluble ions - F, Cl, NO(3), SO(4), Na, NH(4), K, Ca and Mg, employing ion chromatograph. The average mass of PM(10) is found to be 32.75 mug/m(3) with a total water-soluble aerosol load (total anion + total cation) of 13.56 mug/m(3). Composition of aerosol showed higher concentration of SO(4) followed by Na, Ca and NO(3). Very good correlation is observed between crustal ions Ca and Mg (r=0.82) as well as between crustal and acidic ions; Ca and SO(4) (r=0.75) and NO(3) (r=0.67) and Mg and NO(3) (r=0.78) and SO(4) (r=0.73), suggest that the ionic composition was influenced by local terrestrial sources. The presence of SO(4) and NO(3) may be due to re-suspension of soil particles (formation by heterogeneous oxidation). Ca, Mg and Na are mainly soil derived ones. Correlation matrix with meteorological factors, as well as seasonal distribution of PM(10) and its ionic components present a clear trend of higher concentrations during summer due to greater particle release and lowering atmospheric levels during the rainy season due to washout effect. ANOVA results showed the significant variation of composition from season to season. Paired comparisons (DMRT) revealed the occurrence of significant difference in pairs of mean concentration from season to season except within monsoon i.e. between S-W and N-E monsoon.

Air pollution and respiratory status in asthmatic children: hints for a locally based preventive strategy. AIRE study

Respiratory health effects of short-term exposure to ambient air pollution have been examined in 120 'asthma-like' school-aged children in some areas of Emilia-Romagna (urban-industrial and rural area). They kept a daily diary, through 12 weeks, for respiratory symptoms, PEF measurements, drug consumption and daily activity. The average daily concentrations of air pollutants in the same period (TSP, NO2, CO, PM2.5) were higher in the industrial than the rural area. Asthma was diagnosed in 77% of cases, 85% of subjects took medical treatments for respiratory disease in the last year and 90% used medicine for respiratory diseases. Significantly lower variations in PEF, between morning and evening, were observed in the rural area, considering only the asthmatic or cough subsets of children. Symptom prevalence was higher in the urban-industrial area than the rural area; the most frequent symptoms were cough, phlegm and stuffed nose. The two area populations are homogeneous in individual features, family susceptibility, passive smoking exposure and atopy. The differences observed in the frequency of daily reported symptoms could be attributed to external situations like the different reported exposures to pollutants. Although most analyses revealed non-significant associations, panel analysis showed a significant statistical risk for the cough and phlegm group by an increase of 10 microg of TSP (RR 1.0017, 95% CI: 1.0002-1.0033) in the entire group. In the urban-industrial panel we observed a significant association between cough and phlegm together and PM2.5 (RR 1.0044, 95% CI: 1.0011-1.0077). The results of this investigation should be used in orienting local political decisions.

Acid stress in the pathology of asthma

Although alteration of airway pH may serve an innate host defense capacity, it also is implicated in the pathophysiology of obstructive airway diseases. Acid-induced asthma appears in association with gastroesophageal reflux after accidental inhalation of acid (fog, pollution, and workplace exposure) and in the presence of altered airway pH homeostasis. Endogenous and exogenous exposures to acids evoke cough, bronchoconstriction, airway hyperreactivity, microvascular leakage, and heightened production of mucous, fluid, and nitric oxide. Abnormal acidity of the airways is reflected in exhaled breath assays. The intimate mechanisms of acid-induced airway obstruction are dependent on activation of capsaicin-sensitive sensory nerves. Protons activate these nerves with the subsequent release of tachykinins (major mediators of this pathway) that, in conjunction with kinins, nitric oxide, oxygen radicals, and proteases, modulate diverse aspects of airway dysfunction and inflammation. The recognition that acid stress might initiate or exacerbate airway obstructive symptomatology has prompted the consideration of new therapies targeting pH homeostasis.

Acute effects of urban ambient air pollution on respiratory symptoms, asthma medication use, and doctor visits for asthma in a cohort of Australian children

We enrolled a cohort of primary school children with a history of wheeze (n=148) in an 11-month longitudinal study to examine the relationship between ambient air pollution and respiratory morbidity. We obtained daily air pollution (ozone, particulate matter less than 10 microm, and nitrogen dioxide), meteorological, and pollen data. One hundred twenty-five children remained in the final analysis. We used logistic regression models to determine associations between air pollution and respiratory symptoms, asthma medication use, and doctor visits for asthma. There were no associations between ambient ozone concentrations and respiratory symptoms, asthma medication use, and doctor visits for asthma. There was, however, an association between PM(10) concentrations and doctor visits for asthma (RR=1.11, 95% CI=1.04-1.19) and between NO(2) concentration and wet cough (RR=1.05, 95% CI=1.003-1.10) in single-pollutant models. The associations remained significant in multipollutant models. There was no consistent evidence that children with wheeze, positive histamine challenge, and doctor diagnosis of asthma reacted differently to air pollution from children with wheeze and doctor diagnosis of asthma and children with wheeze only. There were significant associations between PM(10) levels and doctor visits for asthma and an association between NO(2) levels and the prevalence of wet cough. We were, however, unable to demonstrate that current levels of ambient air pollution in western Sydney have a coherent range of adverse health effects on children with a history of wheezing.

Particulate air pollution and panel studies in children: a systematic review

BACKGROUND

Panel studies have been used to investigate the short term effects of outdoor particulate air pollution across a wide range of environmental settings.

AIMS

To systematically review the results of such studies in children, estimate summary measures of effect, and investigate potential sources of heterogeneity.

METHODS

Studies were identified by searching electronic databases to June 2002, including those where outcomes and particulate level measurements were made at least daily for > or =8 weeks, and analysed using an appropriate regression model. Study results were compared using forest plots, and fixed and random effects summary effect estimates obtained. Publication bias was considered using a funnel plot.

RESULTS

Twenty two studies were identified, all except two reporting PM10 (24 hour mean) >50 microg x m(-3). Reported effects of PM10 on PEF were widely spread and smaller than those for PM2.5 (fixed effects summary: -0.012 v -0.063 l x min(-1) per microg x m(-3) rise). A similar pattern was evident for symptoms. Random effects models produced larger estimates. Overall, in between-study comparisons, panels of children with diagnosed asthma or pre-existing respiratory symptoms appeared less affected by PM10 levels than those without, and effect estimates were larger where studies were conducted in higher ozone conditions. Larger PM10 effect estimates were obtained from studies using generalised estimating equations to model autocorrelation and where results were derived by pooling subject specific regression coefficients. A funnel plot of PM10 results for PEF was markedly asymmetrical.

CONCLUSIONS

The majority of identified studies indicate an adverse effect of particulate air pollution that is greater for PM2.5 than PM10. However, results show considerable heterogeneity and there is evidence consistent with publication bias, so limited confidence may be placed on summary estimates of effect. The possibility of interaction between particle and ozone effects merits further investigation, as does variability due to analytical differences that alter the interpretation of final estimates.

Acute effect of sulphur dioxide from a power plant on pulmonary function of children, Thailand

BACKGROUND

Epidemiological studies have shown reversible declines of lung function in response to air pollution, but research on the independent effect of short-term exposure to ambient sulphur dioxide (SO2) on pulmonary function is limited. This study evaluated the association of short-term exposure to increased ambient SO2 and daily pulmonary function changes among children with and without asthma.

METHODS

The associations of daily exposure to SO2 and particulate matter 10 microm in diameter (PM10) with pulmonary function were examined in 175 asthmatic and non-asthmatic children aged 6-14 years who resided near a coal-fired power plant in Thailand. Each child performed daily pulmonary function tests during the 61-day study period. General linear mixed models were used to estimate the association of air pollution and pulmonary function controlling for time, temperature, co-pollutants, and autocorrelation.

RESULTS

In the asthmatic children, a daily increase in SO2 was associated with negligible declines in pulmonary function, but a small negative association was found between PM10 and pulmonary function. A 10-microg/m(3) increment was associated with changes in the highest forced vital capacity (FVC) (-6.3 ml, 95% CI: -9.8, -2.8), forced expiratory volume at 1 second (FEV(1)) (-6.0 ml, 95% CI: -9.2, 2.7), peak expiratory flow rate (PEFR) (-18.9 ml.sec(-1), 95% CI: -28.5, -9.3) and forced expiratory flow 25 to 75% of the FVC (FEF(25-75%)) (-3.7 ml.sec(-1), 95% CI: -10.9, 3.5). No consistent associations between air pollution and pulmonary function were found for non-asthmatic children.

CONCLUSION

Declines in pulmonary function among asthmatic children were associated with increases in particulate air pollution, rather than with increases in SO2.

Understanding the seasonal pattern of childhood asthma: results from the National Cooperative Inner-City Asthma Study (NCICAS)

OBJECTIVE

To contrast the seasonal patterns of asthma symptoms and utilization and determine the impact of allergen sensitivity, environmental tobacco smoke (ETS) exposure, and air pollution on the seasonal patterns of asthma.

STUDY DESIGN

Participants in the National Cooperative Inner-City Asthma Study (NCICAS) were tracked for approximately 4 years after allergen skin testing and determination of exposure to ETS. Air pollution data were obtained from EPA monitoring sites in NCICAS cities.

RESULTS

Asthma symptoms (wheeze) and health care utilization (unscheduled visits and hospitalization) had similar seasonal patterns, with low points during the summer months of June through August and a distinct autumn peak beginning in September. Seasonal patterns were similar among children with no allergen skin test reactivity, those reactive only to indoor allergens, and those reactive to outdoor allergens. ETS exposure, whether defined by self-report or urinary cotinine/creatinine ratio, was not related to the observed seasonal patterns. Among the pollutants evaluated, only the seasonal pattern of SO(2) coincided with that of asthma morbidity.

CONCLUSIONS

Atopy, ETS, and most air pollutants do not appear to contribute to the distinct asthma seasonal pattern. On a population level, changes in symptoms are mirrored by changes in utilization.

Effect of ozone and aeroallergens on the respiratory health of asthmatics

The effect of ambient air pollutants, pollens, and mold spores on respiratory health was studied in an area with low concentrations of chemical pollutants and abundant aeroallergens. A panel of 40 asthmatic subjects living near East Moline, Illinois, recorded peak expiratory flow rates (PEFRs), respiratory symptoms, frequency of asthma attacks, and asthma medication use between April and October 1994. Daily outdoor concentrations of pollutants and aeroallergens were measured, and indoor levels of bioaerosols were measured on several occasions in each participant's home. Ozone was associated with increased morning and evening symptom scores and decreased evening PEFR, and these associations remained significant with adjustment for weather and aeroallergens. The association between ozone and asthma medication use was increased in magnitude and significance with adjustment for weather and aeroallergens; however, the association between ozone and morning PEFR became nonsignificant with weather and aeroallergen adjustment. Significant associations were also found between pollen concentration and decreased evening PEFR, as well as between increased morning and evening symptom scores and asthma medication use. In addition, associations were noted between total spore concentration and increased morning PEFR and decreased morning and evening symptom scores. The inverse associations found with mold spore concentrations were not consistent with the results of other studies; however, the associations between ozone and pollen concentration were consistent with previous studies. When results were stratified by a number of independent risk factors, no differences were noted relative to allergic status or presence of dampness or flooding in the home; however, the associations with outdoor ozone and pollens were seen mainly among participants with low levels of exposure to indoor bioaerosols (< 1,800 spores/m3) or with no environmental tobacco smoke exposure.

Poisons in the air: a cause of chronic disease in children

Children represent the largest subpopulation of those susceptible to the adverse effects of air pollution. Compared to adults, children express a greater vulnerability, which can be explained by differences in: the circumstances of exposure related to age, their activities, their child status, differences in lung anatomy and physiology, differences in the clinical expression of disease, and their organ maturity. Many factors have to be assessed in order to evaluate the severity of toxic exposures: pollutant solubility, particle size, concentration, reactivity of pollutants, and pattern of ventilation. Within the numerous air pollutants, some are of special concern for children. For example, ozone has been shown to affect the lungs of healthy school children, especially asthmatics. Airborne particles, nitrogen oxides, sulfur oxides, and acid aerosols have also been shown to induce acute respiratory symptoms, asthma, and bronchitis. Of particular importance is carbon monoxide, which, under certain circumstances, may be found in highly toxic concentrations indoors where children spend most of their time. Special attention has to be given to children's unique differences in order to evaluate the clinical consequences of their toxic exposures. This circumstance emphasizes the key roles of poison centers, clinical toxicologists, and pediatricians, all of whom can collaborate on the identification, assessment, and surveillance of toxic risk for child health and development.

Effects of daily variation in outdoor particulates and ambient acid species in normal and asthmatic children

BACKGROUND

Evidence suggests that the respiratory health of children may be adversely affected by daily variation in outdoor pollutants, particularly ozone and particulates. However, data from the UK are sparse and the contribution of different particulate fractions and acid species, together with the identification of those individuals most at risk, are not clear.

METHODS

One hundred and sixty two 9 year old children were enrolled from two inner city locations and recorded daily symptoms and twice daily peak expiratory flow (PEF) over 8 week periods in the winter and summer. Their results were analysed with daily pollutant levels at appropriate lags using regression models which corrected for trends, weather, pollen, and autocorrelation.

RESULTS

Pollutant levels were generally low, especially in the summer. Multiple statistically significant associations were noted between health outcomes and pollutant concentrations, but no consistent patterns in identified effects were apparent between pollutants, lags, direction of observed effect, or location. There was no evidence to suggest that subgroups with atopy or pre-existing wheeze are more sensitive to pollutant effects.

CONCLUSION

These data do not suggest that adverse health outcomes are associated with daily variations in pollutants [corrected]. No evidence was found to indicate that particulates or individual acid and anion species are more closely related to adverse health outcomes than other pollutants.

Five epidemiological studies on transport and asthma: objectives, design and descriptive results

A case-control study was conducted in five French metropolitan areas in order to assess the role of traffic-related air pollution in the occurrence of childhood asthma. This paper presents the study design and describes the distribution of key exposure variables. A set of 217 pairs of matched 4- to 14-year-old cases and controls were investigated (matching criteria: city, age, and gender). Current and past environmental smoke exposures, indoor allergens or air pollution sources, and personal and family atopy were assessed by standard questionnaires. When possible, direct measurements were done to check the validity of this information, on current data: skin prick tests, urine cotinine, house dust mites densities, personal exposures to, and home indoor concentrations of NO(x) and PM(2.5). Cumulative exposure to traffic-related pollutants was estimated through two indices: "traffic density" refers to a time-weighted average of the traffic density-to-road distance ratio for all home and school addresses of each child's life; "air pollution" index combines lifelong time-activity patterns and ambient air concentration estimates of NO(x), using an air dispersion model of traffic exhausts. Average current PM(2.5) personal exposure is 23.8 microg/m3 (SD=17.4), and average indoor concentrations=22.5 microg/m3 (18.2); corresponding values for NO(2) are 31.4 (13.9) and 36.1 (21.4) microg/m3. Average lifelong calculated exposures to traffic-related NO(x) emissions are 62.6 microg/m3 (43.1). The five cities show important contrasts of exposure to traffic pollutants. These data will allow comparison of lifelong exposures to indicators of traffic exhausts between cases and controls, including during early ages, while controlling for a host of known enhancers or precipitators of airway chronic inflammation and for possible confounders.

Health effects of air pollution exposure on children and adolescents in São Paulo, Brazil

Children and adolescents have been considered more susceptible to the effects of air pollution than adults. In order to investigate the responses of children of different ages to air pollution exposure, daily records of hospital admissions for children in five age groups (equal or less than 2 years of age, 3-5, 6-13, 14-19, and all ages together, i.e., from 0-19 years of age) were obtained from January 1993 to November 1997 in São Paulo, Brazil, and were compared to daily records of PM10, O3, SO2, CO and NO2 concentrations in ambient air. For each age group a generalized additive Poisson regression was fitted controlling for smooth functions of time, temperature, humidity, and days of the week, with an additional indicator for holidays. Polynomial distributed lag models were used to estimate the 7-day cumulative effect of each pollutant. Children 2 years or less were the most susceptible to the effects of all five pollutants with an increase of 9.4% (95% CI: 7.9,10.9) in respiratory admissions associated with each interquartile range increase in PM10. The oldest group was the second most susceptible to air pollutants, with each interquartile range increase in PM10 associated with a 5.1% (95% CI: 0.3,9.8) increase in respiratory admissions. An interquartile range increase in CO was associated with an 11.3% (95% CI: 5.9,16.8) increase in respiratory hospitalizations. When a multipollutant model was used, the effect of PM10 on respiratory admissions for all ages together was unchanged, while the SO2 and the other pollutants effect was substantially reduced. This study showed that daily respiratory hospital admissions for children and adolescents in São Paulo increased with air pollution, and that the largest effects were found for the youngest (2 years or less) and oldest (14-19 years) age groups.

The effect of ozone on inner-city children with asthma: identification of susceptible subgroups

Within a cohort of 846 inner-city asthmatic children aged 4 to 9 yr, we looked for subgroups that were more susceptible to the effects of summer ozone. Daily diaries were compared with ambient ozone levels to evaluate effect modification by demographic and environmental characteristics. Children born > 3 wk prematurely or weighing < 5.5 lb. had greater declines in morning % peak expiratory flow rate (PEFR) (1.8% versus 0.3% per 15 ppb ozone, p < 0.05) and a higher incidence of morning symptoms (odds ratio = 1.42 versus 1.09 per 15 ppb ozone, p < 0.05) than did children who had been full-term infants of normal birthweight. Among children who had been of low birthweight (LBW) or had been premature infants, greater declines were seen among those whose reported baseline medication category was "no medication" (3.2% decline) or "steroids" (2.7%) as opposed to beta agonists or xanthines (0.8%) or cromolyn without steroids (0. 1%). Among the children who had been normal birthweight and full-term infants, the cromolyn without steroids group had the greatest declines in %PEFR (1.3%, versus < 0.5% in each of the other three groups). Nonatopic children also had greater responses to ozone. We conclude that among an asthmatic cohort, children who had had an LBW or a premature birth showed the greatest responses to ozone.

Effects of naturally-occurring acid fog on inflammatory mediators in airway and pulmonary functions in asthmatic patients

Floating fog occurs every summer in Kushiro City in Japan, and the annual average of fog water pH in the past 4 years has been under 5.0. We previously reported that epidemiologically fog was the most important positive factor contributing to increased hospital visits of asthmatic patients compared with other meteorological values and air pollutants. This study aimed to investigate the mechanism of the effects of naturally-occurring acid fog on asthmatic patients. We compared pulmonary functions and inflammatory mediators in induced sputum between the foggy (July 1995) and the non-foggy (May 1996) season, and assessed airway responsiveness to hypo-osmolar aerosol. Forty-four out of 118 asthmatic patients of Kushiro City residents participated, pulmonary function tests were completed in 36 patients, and sputum data were available in 26 patients in both seasons. Percent forced expiratory volume in 1 sec (FEV1) was significantly (P< 0.05) decreased, and % peak expiratory flow rate (PEFR) had a trend to decrease in the foggy season more than in the non-foggy, and sputum eosinophil cationic protein (ECP) and interleukin (IL)-8 were higher in the foggy season but not significantly. A moderate inverse correlation was revealed between sputum ECP and %PEFR in the foggy season (r= -0.55, P<0.005). Subjects were divided into two groups according to the best PEFR; one had >10% lower PEFR levels in the foggy season than in the non-foggy season (Group A, n = 7), the remainder did not (Group B, n = 19). In group A, sputum ECP was significantly increased (P< 0.01) in the foggy season, but there were no changes in IL-8 and prostaglandin D2. Ultrasonic nebulized distilled water provocation test revealed no differences between group A and B. These results suggested that eosinophilic inflammation rather than hypo-osmolar effect of fog might contribute to respiratory deterioration by inhalation of naturally-occurring acid fog.

Effect of air pollution on preterm birth among children born in Southern California between 1989 and 1993

We evaluated the effect of air pollution exposure during pregnancy on the occurrence of preterm birth in a cohort of 97,518 neonates born in Southern California. We used measurements of carbon monoxide (CO), nitrogen dioxide, ozone, and particulate matter less than 10 microm (PM10) collected at 17 air-quality-monitoring stations to create average exposure estimates for periods of pregnancy. We calculated crude and adjusted risk ratios (RRs) for premature birth by period-specific ambient pollution levels. We observed a 20% increase in preterm birth per 50-microg increase in ambient PM10 levels averaged over 6 weeks before birth [RRcrude = 1.20; 95% confidence interval (CI) = 1.09-1.33] and a 16% increase when averaging over the first month of pregnancy (RRcrude = 1.16; 95% CI = 1.06-1.26). PM10 effects showed no regional pattern. CO exposure 6 weeks before birth consistently exhibited an effect only for the inland regions (RRcrude = 1.13; 95% CI = 1.08-1.18 per 3 parts per million), and during the first month of pregnancy, the effect was weak for all stations (RRcrude = 1.04; 95% CI = 1.01-1.09 per 3 parts per million). Exposure to increased levels of ambient PM10 and possibly CO during pregnancy may contribute to the occurrence of preterm births in Southern California.

Relationships between environmental factors and lung function of asthmatic subjects in south east Queensland, Australia

Few panel studies have investigated the relationships between air pollutants and air spora and lung function change in asthmatic subjects. This article examines the association of outdoor air pollutant concentrations and air spora with the decrease in lung function (measured by morning peak expiratory flow) of two groups of asthmatic subjects in the subtropical environment of South East Queensland, Australia. Lung function responses were stratified by age, allergy status, and location, and seasonal effects were examined. Allergy status and age were found to be important, with air pollutants such as ozone and particles associated with decreases in lung function in allergic individuals older than 15 years. Fungal spore counts were strongly associated with a decrease in lung function in allergic adults, especially in those over 54 years, only in seasons when these air spora peak. Analysis for the entire study period indicates that the effect of ozone on peak expiratory flow in the allergic group can sometimes be confounded by air spora effects, indicating that in a subtropical climate the impact of ozone on asthma severity can be accurately estimated only when the confounding effects of air spora are included.

Acute effects of bushfires on peak expiratory flow rates in children with wheeze: a time series analysis

OBJECTIVES

To determine the effects of the January 1994 Sydney bushfire on evening peak expiratory flow rates (PEFR) in children with wheeze.

METHODS

Children with a history of wheeze were enrolled in the longitudinal study and completed a daily asthma diary. We obtained daily air pollution, meteorological, pollen and alternaria data. We then used generalised estimating equation techniques to determine associations between the bushfire period and particulate matter less than 10 microns (PM10) and PEFR.

RESULTS

The maximum daily PM10 level peaked at 210 ug/m3, which was nearly seven times the usual PM10 level for the rest of January and February 1994. There was no significant association between mean PM10 and PEFR (beta-coefficient = -0.009, p = 0.86). Children without bronchial hyper-reactivity had a significant negative association between PEFR and PM10 (beta-coefficient = -0.1029, p = 0.03). The bushfire period was not significant in any of the models.

CONCLUSIONS

We did not find an association between the bushfire period or PM10 and evening PEFR, although in a subgroup of children without bronchial hyper-reactivity, a significant negative association was present between PM10 and evening PEFR.

IMPLICATIONS

We conclude that the high levels of particulate pollution caused by the Sydney bushfires did not lead to any clinically significant reductions in PEFR in symptomatic children. Our results have implications for community risk communication during future bushfires.

Fine particles are more strongly associated than coarse particles with acute respiratory health effects in schoolchildren

Numerous studies have reported associations between airborne particles and a range of respiratory outcomes from symptoms to mortality. Current attention has been focused on the characteristics of these particles responsible for the adverse health effects. We have reanalyzed three recent longitudinal diary studies to examine the relative contributions of fine and coarse particles on respiratory symptoms and peak expiratory flow in schoolchildren. In the Harvard Six Cities Diary Study, lower respiratory symptoms in a two-pollutant model were associated with an interquartile range increment in fine particles [(for 15 microg/m3 particulate matter (PM) <2.5 microm in aerodynamic diameter (PM2.5), odds ratio = 1.29, 95% confidence limits (CL) = 1.06, 1.57] but not coarse particles (for 8 microg/m3 PM2.5-10, odds ratio = 1.05, 95% CL = 0.90, 1.23). In Uniontown, PA, we found that peak flow was associated with fine particles (for 15 microg/m3 PM2.1, peak flow = -0.91 liters/minute, 95% CL = -0.14, -1.68), especially fine sulfate particles, but not with coarse particles (for 15 microg/m3 PM2.1-10, +1.04 liters/minute, 95% CL = -1.32, +3.40). We found similar results for an equivalent children's cohort in State College, PA. We conclude that fine particles, especially fine sulfate particles, have much stronger acute respiratory effects than coarse particles.

Acute effects of urban air pollution on respiratory health of children with and without chronic respiratory symptoms

OBJECTIVES

To investigate to what extent different components of air pollution are associated with acute respiratory health effects in children with and without chronic respiratory symptoms.

METHODS

During three consecutive winters starting in 1992-3, peak expiratory flow (PEF) and respiratory symptoms were registered daily in panels of children of 7-11 years old with and without symptoms, living in urban areas with high traffic intensity in The Netherlands. Simultaneously, panels of children living in non-urban areas were studied. Daily measurements of particles with aerodynamic diameter < 10 microns (PM10), black smoke (BS), sulphate, SO2, and NO2 were performed in both areas.

RESULTS

The contrast in particle concentrations (PM10, BS, and sulphate) between urban and non-urban areas was small, but there was more contrast in the concentrations of SO2 and NO2. In children with symptoms from both areas, significant associations were found between PM10, BS, and sulphate concentrations and the prevalence of symptoms of the lower respiratory tract (LRS) and decrements in PEF. Particle concentrations were also associated with use of bronchodilators in the urban areas, but not in the non-urban areas. After stratification by use of medication, stronger associations were found in children who used medication than in children who did not use medication. The magnitude of the estimated effects was in the order of a twofold increase in the use of bronchodilators, a 50% increase in LRS, and an 80% increase in decrements in PEF for a 100 micrograms/m3 increase in the 5 day mean PM10 concentration. In children without symptoms, significant associations were found between concentrations of PM10 and BS and decrements in PEF in both areas, but these associations were smaller than those for children with symptoms. No associations with respiratory symptoms were found.

CONCLUSIONS

The results suggest that children with symptoms are more susceptible to the effects of particulate air pollution than children without symptoms, and that use of medication for asthma does not prevent the adverse effects of particulate air pollution in children with symptoms.

Association between indoor and outdoor air pollution and adolescent asthma from 1995 to 1996 in Taiwan

The study aim was to estimate the contribution of indoor and outdoor air pollution to the 1-year prevalence of adolescent asthma after personal susceptibility and other potential risk factors were taken into account. A large-scaled cross-sectional study was conducted among 165,173 high school students aged 11 to 16 years in the different communities of Kaohsiung and Pintong in Taiwan, from October 1995 to June 1996. Each student and his/her parents participating in the study completed a video and a written International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire about symptoms of wheezing and allergies, passive smoking, and demographic variables. After adjustment for potential confounders, adolescents exposed to cigarette smoking (odds ratio = 1.29, 95% confidence interval (CI), 1.17-1.42) and environmental tobacco smoke (odds ratio = 1.08, 95% CI, 1.05-1.12) were found to suffer from asthma at an increased frequency. We observed a statistically significant association between outdoor air pollution and asthma, after controlling for potential confound variables. Total suspended particulate, nitrogen dioxide, carbon monoxide, ozone, and airborne dust particles all displayed an independent association with asthma, respectively. There were no selection biases in this community-based study, which provides evidence that passive smoking and long-term, high average outdoor air pollution are independent risk factors of asthma.

Healthy women's PEF variations with ambient summer concentrations of PM10, PM2.5, SO42-, H+, and O3

The relationship between ambient air pollution and daily change in peak expiratory flow (PEF) was studied in a sample of 473 nonsmoking women (age 19 to 43 yr) in Virginia over summers 1995- 1996. Daily 24-h averages of particulate matter (PM2.5 and PM10), fine particulate sulfate (SO42-) and strong acid (H+), hourly ozone (O3), and select meteorologic variables (e.g., temperature) were collected at a regional outdoor monitoring site. Subjects took PEF measurements twice daily for a 2-wk period using a standard MiniWright peak flow meter. Concurrent measures for summer periods of 24-h PM2.5 (micrograms/m3) ranged from 3.5 to 59.7; H+ (nmol/m3) from 0 to 250; maximal daily 8-h average O3 (ppb) from 17.0 to 87.6. Morning PEF decrements were significantly associated with H+ and PM2. 5. An increase of 50 etamol/m3 of H+ and 10 micrograms/m3 of PM2.5 related to decreases of 0.89 (95% CI = 0.21 to 1.57) and 0.73 (95% CI = 0.07 to 1.38) L/min in morning PEF, respectively. Ozone was the only exposure related to evening PEF with 5-d cumulative lag exposure showing the greatest effect; 7.65 L/ min (95% CI = 2.25 to 13.0) decrease per 30 ppb O3 increase. Separate physiologic effects were observed for summer ambient concentrations of two different pollutants (PEF decrements related to PM2.5 in morning and O3 in evening) at concentrations below the new U.S. EPA 24-h ambient air quality standard for PM2.5 and 8-h standard for O3.

Diesel exhaust exposure among adolescents in Harlem: a community-driven study

OBJECTIVES

This study sought individual-level data on diesel exhaust exposure and lung function among adolescents in Harlem as part of a community-driven research agenda.

METHODS

High school students administered in-person surveys to seventh grade students to ascertain information on demographics, asthma history, and self-reported and maternal smoking. Urine samples were assayed for 1-hydroxypyrene (1-HP), a marker of diesel exhaust exposure, and cotinine, a marker of tobacco smoke exposure. Computer-assisted spirometry was used to measure lung function.

RESULTS

Three quarters (76%) of the participating students had detectable levels of 1-HP. Three students (13%) had an FEF25-75 of less than or equal to 80% of their predicted measurements, and 4 students (17%) had results between 80% and 90% of the predicted value, all of which are suggestive of possible lung impairment.

CONCLUSIONS

These data suggest that most adolescents in Harlem are exposed to detectable levels of diesel exhaust, a known exacerbator and possible cause of chronic lung disorders such as asthma. Community-driven research initiatives are important for empowering communities to make needed changes to improve their environments and health.

Short-term effects of low-level winter pollution on respiratory health of asthmatic adults

We studied the short-term effects of Paris winter air pollution (i.e., sulfur dioxide, Black Smoke, suspended particulates with an aerodynamic diameter close to 10 microm, and nitrogen dioxide) in 40 nonsmoking mild to moderate asthmatics (52% male; mean age = 46 y; 90% treated with inhaled steroids). During a 6-mo period, subjects recorded asthma symptoms and three daily peak expiratory flow measurements. Statistical analysis (i.e., generalized estimating equation models that accounted for autocorrelation of responses, weather data, and time trends) revealed consistent and significant associations between the pollutants and asthma attacks and symptoms in the entire study group, especially in the subgroup of individuals who took inhaled beta2 agonists as needed. Pollutants correlated negatively with morning peak expiratory flow in the subgroup that took inhaled beta2 agonists as needed, and they correlated positively with daily variability in asthmatics who received regularly scheduled inhaled beta2 agonists. The effects lingered several days after exposure occurred. Low-level pollution has consistent measurable effects on nonsmoking adults who have well-treated mild or moderate asthma.

Analysis of the relationships between environmental factors (aeroallergens, air pollution, and weather) and asthma emergency admissions to a hospital in Mexico City

There have been several studies of the relationships between environmental factors, particularly air pollution, and attacks of asthma. Most of these studies have ignored the potential confounding effects of aeroallergens such as pollens and fungal spores. We report a statistical analysis of the relationships between emergency admissions for asthma to a hospital in Mexico City and daily average airborne concentrations of pollen, fungal spores, air pollutants (O3, NO2, SO2, and particulates) and weather factors. Asthma admissions had a seasonal pattern with more during the wet season (May-October) than the dry season (November-April). There were few statistical associations between asthma admissions and air pollutants for the three age groups studied (children under 15 years, adults, and seniors [adults over 59 years]) in either season. Grass pollen was associated with child and adult admissions for both the wet and dry seasons, and fungal spores were associated with child admissions during both the wet and dry seasons. The analysis was done with environmental data averaged over the day of admission and the 2 previous days. Our results suggest that aeroallergens may be statistically associated more strongly with asthma hospital admissions than air pollutants and may act as confounding factors in epidemiologic studies.

Acute effects of ambient inhalable particles in asthmatic and nonasthmatic children

Although increases in inhalable particle (PM10) concentrations have been associated with acute reductions in the level of lung function and increased symptom reporting in children, including children with asthma, it is not clear whether these effects occur largely in asthmatic children, or even whether asthmatic children are more likely to experience these effects than children without asthma. To address these points, the following subgroups of children were selected from a survey population of all 2,200 elementary school children (6 to 13 yr of age) in a pulp mill community on the west coast of Vancouver Island: (1) all children with physician-diagnosed asthma (n = 75 participated), (2) all children with an exercise-induced fall in FEV1 without diagnosed asthma (n = 57), (3) all children with airway obstruction (FEV1/FVC < 0.76) without either of the above (n = 18), and (4) control children without any of the above (n = 56). The children were followed for as long as 18 mo with twice daily measurements of peak expiratory flow (PEF) and daily symptom diary recording. Maximum daily PM10 concentration was 159 microm/m3 (median, 22.1), but only 8 d (1.2%) had concentrations above 100 microg/m3. In an analysis that accounted for time-varying covariates, and serially correlated and missing data, for the entire sample of children, increases in PM10 were associated with reductions in PEF and increased reporting of cough, phlegm production, and sore throat. For the subgroup of children with diagnosed asthma, PEF in the time period with the highest PM10 concentrations fell by an estimated 0.55 L/min (95% CI, 0.06 to 1.05) for a 10 microg/m3 PM10 increase above the mean daily PM10 concentration of 27.3 microg/m3 and the odds of reported cough increased by 8% (95% CI, 0 to 16%); no consistent effects were observed in the other groups of children. It is concluded that children experience reductions in PEF and increased symptoms after increases in relatively low ambient PM10 concentrations, and that children with diagnosed asthma are more susceptible to these effects than are other children.

Personal exposure to nitrogen dioxide pollution and effect on plasma antioxidants

We conducted a cross-sectional epidemiological study to evaluate personal exposure to nitrogen dioxide and its effect on blood antioxidants. Personal exposure of 107 volunteers was assessed for 14 d with passive monitors. We excluded heavy smokers (> 10 cigarettes/d) from the study. Sociodemographic and environmental data, as well as beta-carotene intake, were recorded. We mainly attributed the mean nitrogen dioxide personal exposure (31.9 +/- 12.7 microg/m3 [0.017 ppm or 0.70 microM/m3]) (R2 = 0.75) to residence site in the city, time spent in urban traffic, and use of gas stoves. The correlation between nitrogen dioxide exposure and blood antioxidant concentration was weak; in addition, the correlation coefficients for men and women were inconsistent. Nonetheless, we found some evidence of an interaction between carotene intake and nitrogen dioxide exposure: a significantly lower plasma beta-carotene level was evident among subjects who consumed < or = 4.5 mg/jour of carotene and who were exposed to nitrogen dioxide levels that exceeded 40 microg/m3 (0.021 ppm or 0.87 microM/m3) of nitrogen dioxide.