The Chattanooga school children study: effects of community exposure to nitrogen dioxide. 1. Methods, description of pollutant exposure, and results of ventilatory function testing

Air pollution irreversibly impairs lung function: a twenty-year follow-up of officially acknowledged victims in Japan

Lung function is one of the strongest determinants of cardiopulmonary health and longevity. Long-term exposure to air pollution has been associated with decreased lung function. We undertook a retrospective study to compare the long-term consequences of air pollution in two areas of Japan: Mizushima, Okayama Prefecture and Kitakyushu, Fukuoka Prefecture. Industrialization began in Mizushima in the 1940s, whereas it began in Kitakyushu in the early 1900s. In Kitakyushu, levels of nitrogen dioxide have been higher compared to the Mizushima area. The subjects comprised 623 officially acknowledged victims of pollution-related illness (489 from Mizushima and 134 from Kitakyushu). All subjects were lifetime non-smokers and aged 65 years or older at the time of their last medical examination in 2009. Demographic data including diagnosed lung diseases and lung function at the time of certification assessment performed between 1973 and 1988 were obtained. The subjects from Kitakyushu were significantly younger (47.1 vs. 51.0 years, p < 0.001) and a higher percentage had asthma (91.2 vs. 36.8%, p < 0.001) compared to those from Mizushima. Furthermore, all measures of lung function were significantly lower in Kitakyushu group at the time of the certification assessment (p < 0.001) and at the follow-up (p < 0.001). However, no significant differences were observed in the annual mean decline in lung function between the two groups, despite the overall decrease in air pollution. In conclusion, the normal lung function is not restored even after improvement of air pollution. It is essential for every city to prevent air pollution.

Critical review of the human data on short-term nitrogen dioxide (NO2) exposures: evidence for NO2 no-effect levels

Nitrogen dioxide (NO2) is a ubiquitous atmospheric pollutant due to the widespread prevalence of both natural and anthropogenic sources, and it can be a respiratory irritant when inhaled at elevated concentrations. Evidence for health effects of ambient NO2 derives from three types of studies: observational epidemiology, human clinical exposures, and animal toxicology. Our review focuses on the human clinical studies of adverse health effects of short-term NO2 exposures, given the substantial uncertainties and limitations in interpretation of the other lines of evidence. We examined more than 50 experimental studies of humans inhaling NO2, finding notably that the reporting of statistically significant changes in lung function and bronchial sensitivity did not show a consistent trend with increasing NO2 concentrations. Functional changes were generally mild and transient, the reported effects were not uniformly adverse, and they were not usually accompanied by NO2-dependent increases in symptoms. The available human clinical results do not establish a mechanistic pathway leading to adverse health impacts for short-term NO2 exposures at levels typical of maximum 1-h concentrations in the present-day ambient environment (i.e., below 0.2 ppm). Our review of these data indicates that a health-protective, short-term NO2 guideline level for susceptible (and healthy) populations would reflect a policy choice between 0.2 and 0.6 ppm. EXTENDED ABSTRACT: Nitrogen dioxide (NO2) is a ubiquitous atmospheric pollutant due to the widespread prevalence of both natural and anthropogenic sources, and it can be a respiratory irritant when inhaled at elevated concentrations. Natural NO2 sources include volcanic action, forest fires, lightning, and the stratosphere; man-made NO2 emissions derive from fossil fuel combustion and incineration. The current National Ambient Air Quality Standard (NAAQS) for NO2, initially established in 1971, is 0.053 ppm (annual average). Ambient concentrations monitored in urban areas in the United States are approximately 0.015 ppm, as an annual mean, i.e., below the current NAAQS. Short-term (1-h peak) NO2 concentrations outdoors are not likely to exceed 0.2 ppm, and even 1-h periods exceeding 0.1 ppm are infrequent. Inside homes, 1-h NO2 peaks, typically arising from gas cooking, can range between 0.4 and 1.5 ppm. The health effects evidence of relevance to ambient NO2 derives from three lines of investigation: epidemiology studies, human clinical studies, and animal toxicology studies. The NO2 epidemiology remains inconsistent and uncertain due to the potential for exposure misclassification, residual confounding, and co-pollutant effects, whereas animal toxicology findings using high levels of NO2 exposure require extrapolation to humans exposed at low ambient NO2 levels. Given the limitations and uncertainties in the other lines of health effects evidence, our review thus focused on clinical studies where human volunteers (including asthmatics, children, and elderly) inhaled NO2 at levels from 0.1 to 3.5 ppm during short-term ((1/2)-6-h) exposures, often combined with exercise, and occasionally combined with co-pollutants. We examined the reported biological effects and classified them into (a) lung immune responses and inflammation, (b) lung function changes and airway hyperresponsiveness (AHR), and (c) health effects outside the lungs (extrapulmonary). We examined more than 50 experimental studies of humans inhaling NO2, finding that such clinical data on short-term exposure allowed discrimination of NO2 no-effect levels versus lowest-adverse-effects levels. Our conclusions are summarized by these six points: For lung immune responses and inflammation: (1) healthy subjects exposed to NO2 below 1 ppm do not show pulmonary inflammation; (2) at 2 ppm for 4 h, neutrophils and cytokines in lung-lavage fluid can increase, but these changes do not necessarily correlate with significant or sustained changes in lung function; (3) there is no consistent evidence that NO2 concentrations below 2 ppm increase susceptibility to viral infection; (4) for asthmatics and individuals having chronic obstructive pulmonary disease (COPD), NO2-induced lung inflammation is not expected below 0.6 ppm, although one research group reported enhancement of proinflammatory processes at 0.26 ppm. With regard to NO2-induced AHR: (5) studies of responses to specific or nonspecific airway challenges (e.g., ragweed, methacholine) suggest that asthmatic individuals were not affected by NO2 up to about 0.6 ppm, although some sensitive subsets may respond to levels as low as 0.2 ppm. And finally, for extra-pulmonary effects: (6) such effects (e.g., changes in blood chemistry) generally required NO2 concentrations above 1-2 ppm. Overall, our review of data from experiments with humans indicates that a health-protective, short-term-average NO2 guideline level for susceptible populations (and healthy populations) would reflect a policy choice between 0.2 and 0.6 ppm. The available human clinical results do not establish a mechanistic pathway leading to adverse health impacts for short-term NO2 exposures at levels typical of maximum 1-h concentrations in the present-day ambient environment (i.e., below 0.2 ppm).

A New Method for Atmospheric Nitrogen Dioxide Measurements Using the Combination of a Stripping Coil and Fluorescence Detection

A new stripping coil for the collection of nitrogen dioxide (NO2) has been developed to increase its versatility and efficiency. Nitrogen dioxide measurements based on quantitative collection through a reaction coil into an alkaline solution has been examined. Nitrogen dioxide is collected in a 0.1 N NaOH solution. This collection system has an efficiency of nearly 100%. The absorbed nitrogen dioxide has been measured by fluorescence detection with sub-ppbv detection limits. The excitation wavelength at 360 nm and the produced emission wavelength at 405 nm were suitable for nitrite ion measurements.

Urinary hydroxyproline as a biomarker of effect after exposure to nitrogen dioxide

A cross-sectional study was carried out on two groups of subjects differently exposed to nitrogen dioxide in order to test the urinary hydroxyproline ratio (UHP/mg/24 h/m(2)) as a biomarker of effect after exposure to this pollutant. UHP was determined in samples of 58 subjects divided into two groups comparable to as lifestyle and training. The first group was composed of 29 subjects who used to do jogging in urban areas polluted by nitrogen dioxide. The second group was made up of 29 subjects who used to do jogging in non-polluted countryside areas. The mean concentration of UHP of urban joggers was 25.02+/-9.21 mg/24 h/m(2), whereas in those training in the countryside it was 13.78+/-6.68 mg/24 h/m(2). Thus, UHP was higher in subjects training in areas polluted by nitrogen dioxide than in the subjects training in non-polluted areas.

Increased urinary excretion of hydroxyproline in runners training in urban areas

In this study, the authors investigated urinary excretion of hydroxyproline in 120 subjects to test the hypothesis that physical activity is associated with increased exposure to pollution derived from traffic exhaust. The study population comprised active noncompetitive runners (i.e., 21.1% trained < 2.5 hr/wk, 20% trained for 2.5-5.0 hr/wk, and 54.4% trained > 5 hr/wk) who lived in Genoa, an urban area of Northern Italy. The mean hydroxyproline value (24.39 +/- 8.38 standard deviation] mg/24 hr x m2) in a group of 69 runners who trained in tracks and streets located in downtown Genoa was higher (p < .05) than the mean value recorded in a group of 21 runners (13.33 +/- 2.51 mg/24 hr x m2) who trained mainly in a rural environment of Genoa. The difference was even greater (p < .01) when a third comparable group of 30 nonrunners was considered (mean = 12.54 +/- 3.41 [standard deviation] mg/24 hr x m2). In the urban environment, urinary levels of hydroxyproline were correlated significantly with intensity and frequency of running, but they were unrelated to smoking status.

Epidemiologic study design for investigating respiratory health effects of complex air pollution mixtures

Epidemiologic studies of the respiratory health effects of air pollution are intrinsically difficult because exposure is common, expected effects at concentrations found in developed countries are weak, random misclassification of exposure is common, and the respiratory health indicators have multiple etiologies. Exposures to air pollutants also are multidimensional, generally consisting of a mixture of gases and particles. In this paper, epidemiologic study designs are described, and their potential for evaluating effects of complex pollutant mixtures are discussed. Power to detect the independent effects of individual pollutants in a complex pollutant mixture or to measure their interactions is in general very weak unless the study is specifically designed to test such hypotheses. However, with innovative and creative design, the independent and joint effects of multiple pollutants should be estimable in epidemiologic studies.

Indoor nitrogen dioxide and childhood respiratory illness

Nitrogen dioxide is produced from the combustion of fossil fuels and as an emission from gas-fired appliances, and is also a component of tobacco smoke. Nitrogen dioxide has been shown in experimental animals to be toxic to the respiratory tract. A n number of recent studies have suggested that children exposed to significant levels of nitrogen dioxide in the home may be more susceptible to respiratory illness than children exposed to normal ambient levels. Respiratory illness is a major cause of morbidity in children everywhere. Here, we review the available evidence of this association and explore methodological issues in measurement of nitrogen dioxide exposure--misclassification of subjects, symptom bias and confounding. It has recently been shown that some New South Wales school rooms, where unflued gas heaters are often used as a source of warmth, have nitrogen dioxide levels which are above recommended ambient levels for outside air. This has underlined the need for setting standards for indoor levels of various pollutants, and cohort studies are suggested, to include personal monitoring and prospective data collection techniques.

Personal and indoor/outdoor nitrogen dioxide exposure assessments of 23 homes in Taiwan

Indoor and outdoor nitrogen dioxide (NO2) concentrations of 23 homes from two areas in Taiwan, the city of Taipei and a rural village in central Taiwan, were measured concurrently from December 1987 to January 1988. NO2 measurements were carried out by Palmes tube for one week and filter badges for two days. In Taipei, the mean NO2 concentrations outdoors, in the kitchens, in the livingrooms, and in the bedrooms were 40.1 ppb, 34.4 ppb, 32.1 ppb, and 29.7 ppb for one week, and were 25.7 ppb, 25.6 ppb, 22.6 ppb, and 20.5 ppb for two days. In the village of central Taiwan, the corresponding concentrations were 23.5 ppb, 24.5 ppb, 20.4 ppb, and 17.5 ppb for one week, and 20.3 ppb, 24.7 ppb, 18.8 ppb, and 15.4 ppb for two days. The NO2 concentrations of all microenvironments in Taipei were significantly higher than those in the village of central Taiwan. The outdoor NO2 concentrations were significantly higher than the indoor NO2 concentrations in Taipei. The NO2 measurements in the kitchens were higher than all other measurements indoors and outdoors in the village of central Taiwan. The houses which used natural gas as cooking fuel had slightly higher indoor NO2 concentrations than the houses which used LPG as cooking fuel in Taipei city. Cement houses had slightly higher indoor NO2 concentrations than brick houses. The mean of housewives' exposures was 30.8 ppb in Taipei and 19.9 ppb in the village of central Taiwan. The explanation power of the housewife's exposure to NO2 was 72% by the time weighted-average model and 70% by the simple linear regression model.

Personal exposure and health effect relationship for NO2 with urinary hydroxyproline to creatinine ratio as indicator

Establishment of an exposure-effect relationship was attempted between personal nitrogen dioxide (NO2) exposure and urinary hydroxyproline to creatinine ratio of approximately 800 adult women, who were mothers of primary schoolchildren living in two communities around Tokyo. Daily average of the personal NO2 exposure (ENO2) was measured during wintertime by a newly developed personal monitor exposed for 24 hours. The hydroxyproline to creatinine ratio (HOP:C) in the urine sample collected early in the morning of the day for ENO2 measurement was used as a biochemical indicator of the health effect of NO2 exposure. The HOP:C was found to have significant correlation with ENO2 and number of cigarettes smoked actively and passively. ENO2, however, had no correlation with the intensity of the smoking levels; they might affect HOP:C independently. Stepwise multiple regression analysis revealed that HOP:C could be predicted by ENO2 and smoking habits at a high confidence level. The regression analysis of the active smokers' group indicated that a few cigarettes was enough to increase the HOP:C, while in the case of passive smoking, HOP:C increased proportionally to the number of cigarettes.

[Air pollution and respiratory tract diseases in children]

Children are particularly susceptible for respiratory diseases, this is why studies on health effects of air pollution are often investigating children. Children have some other advantages: they do not smoke and they are not exposed to potentially noxious environment at work, also they spend their time fairly constantly in their usual environment. Studies from England and the United States show higher incidence of acute and a higher prevalence of chronic respiratory disease in children living in areas with higher concentration of air pollutants than in groups living in areas with lower concentration of pollutants. Some studies show these effects in concentration similar to those observed in swiss townships. Nevertheless specific studies in Switzerland are indicated in order to investigate the effect of the particular composition of pollutants in Switzerland and to assess effects of future possible improvements of the air quality.

The Tayside infant morbidity and mortality study: effect on health of using gas for cooking

The relation between respiratory illness and the use of gas for cooking was examined from data on 1565 infants born to mothers who were primigravidas living in Dundee in 1980. Episodes of, and admissions to hospital for, respiratory illness were recorded during the first year of life. Both admissions and episodes were more common in infants from families using gas for cooking or heating than in infants from families using any other type of cooking or heating, but the differences were not significant. Results from this and other studies show that there is probably a small relation between respiratory illness and the use of gas appliances without a flue. To show convincingly whether such a relation exists might require a survey of 18 000-23 000 subjects. Respiratory illness was, however, strongly and positively related to parental smoking, a finding that is often made even in small studies.

Risk factors associated with the development of chronic lung disease in children

By better understanding the intrinsic and extrinsic factors that predispose children to chronic lung disease, strategies to prevent its development can be proposed. This article addresses conditions, such as bronchiolitis, croup, hyaline membrane disease, hydrocarbon ingestion, and near-drowning, that have been found to result in long-term changes in lung physiology. Also considered are the possible relationships of common respiratory infection, asthma, smoking, and air pollution to the development of chronic respiratory infection.

Modulation of nitrogen dioxide toxicity by lithium

The effect of short-term intake of LiCl in drinking fluid on NO2 toxicity was studied in mice as a function of mortality and of specific activities of mouse liver alcohol dehydrogenase (L-ADH) and aldehyde dehydrogenases (L-ALDH). Pretreatment with LiCl for 10 days decreased mortality in mice exposed to 60 to 70 PPM NO2 for 6 hr compared to controls. Pretreatment with LiCl for 10 days under continued exposure to 5 PPM NO2 resulted in a decrease in liver weight compared to control. Lithium treated mice exposed to NO2 showed less gain in body weight than the controls treated with LiCl and exposed to air. The latter group showed an induction of mitochondrial but not cytoplasmic L-ALDH and the NO2 exposure did not alter endogenous L-ALDH from corresponding controls. This induction of mitochondrial ALDH was associated with an increase in both Vmax and the apparent Km. Exposure to NO2 for 10 consecutive days resulted in inhibition of cytoplasmic L-ALDH. The data suggest that Li+ antagonized NO2 toxicity. A possible mechanism for reduction of NO2 toxicity by LiCl may be due to Li+ action on stabilizing cell membranes and/or modifying intercellular pulmonary response to NO2 injury.

Acute respiratory symptoms in patients with chronic obstructive pulmonary disease and in other subjects living near a coal-fired plant

Daily symptom rates in patients with chronic obstructive pulmonary disease and in other subjects with presumed high sensitivity to air pollution who lived near a coal-fired plant were compared with 24-hr ambient air concentrations of nitrogen dioxide, sulfur dioxide, soot, and suspended particles as well as with emissions from the plant. The mean concentrations of each of the pollutants during the 4-month study period were below 30 micrograms/m3, and no single 24-hr concentration exceeded 100 micrograms/m3. There were no consistent associations between plant emissions and pollutant levels or between these two variables and daily symptom rates. The results indicate that the coal-fired plant was not of major importance for the occurrence of acute respiratory symptoms in the surrounding population.

An epidemiological study of salt miners in diesel and nondiesel mines

A cross-sectional study of 5 NaCl mines and 259 miners addressed the following questions: 1) Is there an association of increased respiratory symptoms, radiographic findings, and reduced pulmonary function with exposure to nitrogen dioxide (NO2) and/or respirable particulate (RP) among these miners? 2) Is there increased morbidity of these miners compared to other working populations? Personal samples of NO2 and respirable particulate for jobs in each mine were used to estimate cumulative exposure. NO2 is used as a surrogate measure of diesel exposure. Cough was associated with age and smoking, dyspnea with age; neither symptom was associated with exposure (years worked, estimated cumulative NO2 or RP exposure). Phlegm was associated with age, smoking, and exposure. Reduced pulmonary function (FVC, FEV1, peak, flow, FEF50, FEF75) showed no association with exposure. There was one case of small rounded and one case of small irregular opacities; pneumoconiosis was not analyzed further. Compared to underground coal miners, above ground coal miners, potash miners, and nonmining workers, the study population after adjustment for age and smoking generally showed no increased prevalence of cough, phlegm, dyspnea, or obstruction (FEV1/FVC less than 0.7). Obstruction in younger salt miners and phlegm in older salt miners was elevated compared to nonmining workers. Mean predicted pulmonary function was reduced 2-4% for FEV1 and FVC, 7-13% for FEF50, and 18-22% for FEF75 below all comparison populations.

Acute respiratory illness in families exposed to nitrogen dioxide ambient air pollution in Chattanooga, Tennessee

The incidence of acute respiratory illness in families in Chattanooga, Tennessee was studied in 1972 and 1973 to determine if residents of a formerly high nitrogen dioxide exposure community continued to experience a high incidence of illness after ambient air concentrations of the pollutant had been reduced substantially. Illness data were collected by telephone at 2-wk intervals and illness rates per 100 person weeks of observation were contrasted with air pollution concentrations measured no more than 3.2 km from the home. Data were contrasted by communities designated as high, intermediate, or low pollution exposure. In 1972, higher rates of respiratory illness continued to occur in the designated high pollution area. These were associated with current higher short-term concentrations of nitrogen dioxide even though the long-term mean concentrations of the pollutant were little higher than those in the low pollution area. It was not possible to attribute the excesses in illness to specific pollutants or to specific exposure periods. However, reduction of the illness rate in 1973 associated with a strike at the primary source industry that curtailed nitrogen dioxide pollution in the high exposure community suggested that the short-term exposure may be more important than long-term exposure.

The incidence and severity of acute respiratory illness in families exposed to different levels of air pollution, New York metropolitan area, 1971-1972

The incidence and severity of acute respiratory disease was studied in families in three New York communities with different ambient levels of SO2 and particulate air pollution. Upper, lower, and total respiratory disease rates in fathers, mothers, and school children tended to be higher in the communities with higher pollution levels. Similar higher rates, however, were not observed among preschool children. Regression analyses were used to adjust rates for socioeconomic status, parental smoking, chronic bronchitis in parents, and possible indoor pollution resulting from the use of a gas stove for cooking. After these adjustments the community differences were still significant (P less than .01), for schoolchildren. The indoor pollution related to gas stoves was a significant covariate among children. The effects of smoking were inconsistent. It was not possible to attribute the higher rates observed to any specific pollutant, since both SO2 and particulate matter levels were higher in the high pollution communities, nor was it possible to attribute the excesses to current levels of exposure or to a residual effect of previous higher exposure concentrations. The fact that young children did not follow the pattern suggests the latter. It was concluded, however, that current or previous exposures to the complexity of air pollutants in New York City was at least partially responsible for increased incidences of acute respiratory disease.

Air pollution and COPD

Air pollution referable to increased ambient levels of sulfur dioxide and suspended particulates is associated with increased episodes of acute bronchitis and is also causally related to some cases of chronic bronchitis. Oxidant air pollution is associated with abnormalities of pulmonary function in children and is a major contributory factor in COP, especially bronchitis, in some areas of the United States. The relationship of nitrogen dioxide atmospheric contamination to COPD is still controversial. In our opinion, the epidemiologic studies conducted to date have been inadequate and further elucidation is indicated. Cadmium fumes and compounds have been found to be instrumental in the development of some cases of chronic bronchitis and emphysema in Sweden. This association is unproved in the United States and warrants a thorough clinical and epidemiologic evaluation.