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PubMed1997

Frequency of patients with acute asthma in relation to ozone, nitrogen dioxide, other pollutants of ambient air and meteorological observations.

OBJECTIVE: To study the association of the daily frequency of registration of patients with acute asthma at the emergency department of a central hospital in the south-west of Sweden with levels of air pollution and meteorological observations. METHODS: A retrospective longitudinal study was made of asthma patients taken from a hospital registry. This information was correlated with measurements of ozone, nitrogen dioxide, sulphur dioxide, toluene, temperature and relative humidity. Patients were from the catchment area of the Central Hospital of Halmstad containing around 120,000 inhabitants. A total of 4127 visits of patients with acute asthma to the emergency department at the Central Hospital of Halmstad were registered during a period of 1247 days from January 1990 to May 1993. The differential optical absorption spectroscopy (DOAS) technique was used to monitor levels of air pollutants over a distance of 1000 m in the central part of the town of Halmstad. Data on temperature, relative humidity, precipitation, wind speed and wind direction for the time period were supplied by the Swedish Meteorological and Hydrological Institute (SMHI). RESULTS: There were many statistically significant correlations between the levels of air pollutants and the meteorological measurements and a strong negative correlation between ozone and nitrogen dioxide. There was a statistically significant effect on asthma visits in children of low temperature and high nitrogen dioxide levels, and on asthma visits in adults of high temperature and high levels of ozone. CONCLUSIONS: There was a different reaction pattern in children and adults with asthma regarding temperature and ozone/nitrogen dioxide. The strong correlations between temperature and air pollution and between the levels of ozone and nitrogen dioxide made the true relation between asthma, air pollution and temperature hard to evaluate statistically.

Acute Disease↗

PubMed1989

Reduction in T lymphocyte subpopulations following acute exposure to 4 ppm nitrogen dioxide.

The effect of acute exposure to nitrogen dioxide (NO2) on splenic T lymphocyte subpopulations was studied in C57BL/6cum mice. The mice were exposed to 4 ppm NO2 for 8 hr. Monoclonal antibodies to T lymphocyte differentiation antigens and fluorescence-activated cell sorter (FACS) analysis were used to detect changes in T lymphocyte subpopulations. Percentages of total T lymphocytes (Thy-1.2-positive), T-helper/inducer lymphocytes (L3T4-positive), and T-cytotoxic/suppressor lymphocytes (Lyt-2-positive) were significantly lower in NO2-exposed animals than in filtered-air-breathing controls. Large T-cytotoxic/suppressor cells were found to be the most susceptible subpopulation. Spleen and body weights of the mice were also determined. There were no differences between body weights of control and exposed animals; however, exposed mice had significantly lower spleen weights. This is the first report providing evidence linking alterations in T lymphocyte subpopulations to acute NO2 exposure at occupational levels. T lymphocytes play a central role in regulatory and effector immunological functions such as mediating delayed hypersensitivity, regulating immunoglobulin production, and lysing virus-infected and neoplastic cells. The biological significance of these findings remains to be established, but it is very likely that functional impairment occurs since an optimal immune response depends upon a proper balance of the T lymphocyte subpopulations. Detection of alterations in T lymphocyte subpopulations using monoclonal antibodies and FACS analysis may provide an extremely sensitive means of demonstrating NO2-induced changes in the immune system.

Animals↗

PubMed2001

Detection of poly(ADP-ribose) synthetase activity in alveolar macrophages of rats exposed to nitrogen dioxide and ozone.

The toxic effects of nitrogen dioxide (NO2) and ozone (O3) are mediated through the formation of free radicals, which can cause DNA strand breaks. The present study demonstrates that exposure to NO2 and O3 causes a stimulation of poly(ADP-ribose) (polyADPR) synthetase in alveolar macrophages of rats. Three-month-old male Sprague-Dawley rats, specific pathogen free, were exposed to either 1.2 ppm NO2 or 0.3 ppm O3 alone or a combination of these 2 oxidants continuously for 3 days. The control group was exposed to filtered room air. To evaluate whether exposure to these two oxidants (NO2 and O3) caused DNA damage to lung cells, the activity of polyADPR synthetase was measured. Cellular DNA repair is dependent upon the formation of poly(ADP-ribose) polymerase, which is catalyzed by polyADPR synthetase. PolyADPR synthetase is known to be activated in response of DNA damage. The results showed that the enzyme activity was stimulated after exposure to O3 or exposure to NO2 + O3. Ozone exposure caused a 25% increase in the enzyme activity as compared to the control. Combined exposure to NO2 + O3 showed a 53% increase in the enzyme activity. These results were statistically significant as compared to the control and NO(2) exposure groups. Other parameters such as total cell count, cell viability, and differential cell count were also determined. The stimulation of polyADPR synthetase activity after O3 exposure or NO2 + O3 exposure reflects a response to lung cellular DNA repair, which may be used as an indicator for assessing DNA damage caused by oxidant injury.

Administration, Inhalation↗

PubMed2006

Evaluation of ogawa passive sampling devices as an alternative measurement method for the nitrogen dioxide annual standard in El Paso, Texas.

Nitrogen Dioxide (NO(2)) is a common urban air pollutant that results from the combustion of fossil fuels. It causes serious human health effects, is a precursor to the formation of ground level ozone, another serious air pollutant, and is one of the six criteria air pollutants established by the United States (U.S.) Clean Air Act (CAA). Ogawa Passive Sampling Devices (PSDs) for NO(2) were collocated and operated at six NO(2) Federal Reference Method (FRM) monitor locations in the El Paso, Texas area for the 2004 calendar year. Passive samples were taken at 2-week, 3-week, and 4-week intervals and compared against the continuously operating FRM monitors. Results showed that the collective NO(2) annual arithmetic mean for all passive monitors was identical to the NO(2) mean for all FRM monitors. Of the individual locations, three passive annual NO(2) means were identical to their corresponding FRM means, and three passive annual NO(2) means differed from their corresponding FRM means by only one part per billion (ppb). Linear correlation analysis between all readings of the individual NO(2) PSDs and FRM values showed an average absolute difference of 1.2 ppb with an r (2) of 0.95. Paired comparison between high and low concentration annual NO(2) sites, seasonal considerations, and interlab quality control comparisons all showed excellent results. The ease of deployment, reliability, and the cost-savings that can be realized with NO(2) PSDs could make them an attractive alternative to FRM monitors for screening purposes, and even possibly an equivalent method for annual NO(2) monitoring. More tests of the Ogawa NO(2) PSD are recommended for different ecosystem and climate regimes.

Air Pollutants↗

PubMed2000

Effect of outdoor and indoor nitrogen dioxide on respiratory symptoms in schoolchildren.

BACKGROUND: Nitrogen dioxide (NO(2)), an oxidant gas that contaminates both outdoor and indoor air, is considered to be a potential risk factor for asthma. We investigated concurrently the effects of outdoor and indoor NO(2) on the prevalence and incidence of respiratory symptoms among children. METHODS: A cohort study was carried out over 3 years on 842 schoolchildren living in seven different communities in Japan. Indoor NO(2) concentrations over 24 hours were measured in both winter and summer in the homes of the subjects, and a 3-year average of the outdoor NO(2) concentration was determined for each community. Respiratory symptoms were evaluated every year from responses to questionnaires. RESULTS: The prevalence of bronchitis, wheeze, and asthma significantly increased with increases of indoor NO(2) concentrations among girls, but not among boys. In neither boys nor girls were there significant differences in the prevalence of respiratory symptoms among urban, suburban, and rural districts. The incidence of asthma increased among children living in areas with high concentrations of outdoor NO(2). Multiple logistic regression analysis showed that a 10 parts per billion (ppb) increase of outdoor NO(2) concentration was associated with an increased incidence of wheeze and asthma (odds ratios [OR] = 1.76, 95% CI : 1.04-3.23 and OR = 2.10, 95% CI : 1.10-4.75, respectively), but that no such associations were found with indoor NO(2) concentration (OR = 0.73, 95% CI : 0.45-1.14 and OR = 0.87, 95% CI : 0.51-1.43, respectively). CONCLUSIONS: These findings suggest that outdoor NO(2) air pollution may be particularly important for the development of wheeze and asthma among children. Indoor NO(2) concentrations were associated with the prevalence of respiratory symptoms only among girls. Girls may be more susceptible to indoor air pollution than boys.

Air Pollutants↗

PubMed2002

Measurements of personal exposure to nitrogen dioxide in four Mexican cities in 1996.

Nitrogen dioxide is a ubiquitous pollutant in urban areas. Indoor NO2 concentrations are influenced by penetration of outdoor concentrations and by indoor sources. The objectives of this study were to evaluate personal exposure to NO2, taking into account human time-activity patterns in four Mexican cities. Passive filter badges were used for indoor, outdoor, and personal NO2 measurements over 48 hr and indoor workplace measurements over 16 hr. Volunteers completed a questionnaire on exposure factors and a time-activity diary during the sample period. An unpaired t test, an analysis of variance (ANOVA), and a linear regression were performed to compare differences among cities and mean personal NO2 concentrations involving housing characteristics, as well as to determine which variables predicted the personal NO2 concentration. Sampling periods were in April, May, and June 1996 in Mexico City, Guadalajara, Cuernavaca, and Monterrey. All 122 volunteers in the study were working adults, with a mean age of 34 (SD +/- 7.38); 64% were female, and the majority worked in public offices and universities. The highest NO2 concentrations were found in Mexico City (36 ppb for outdoor, 57 ppb for indoor, and 39 ppb for personal concentration) and the lowest in Monterrey (19 ppb for outdoor, 24 ppb for indoor, and 24 ppb for personal concentration). Significant differences in NO2 concentrations were found among the cities in different microenvironments. During the sampling period, volunteers spent 85% of their time indoors. The highest personal NO2 concentration was found when volunteers kept their windows closed (p = 0.03). In the regression model adjusted by city and gender, the best predictors of personal NO2 concentration were outdoor levels and time spent outdoors (R2 = 0.68). These findings suggest that outdoor NO2 concentrations were an important influence on the personal exposure to NO2, due to the specific characteristics and personal behavior of the people in these Mexican cities.

Adult↗

PubMed1982

Electrocardiographic abnormalities in rats by acute exposure to nitrogen dioxide.

Changes in cardiac function of rats acutely exposed to nitrogen dioxide (NO2) were examined by electrocardiographic (ECG) records. Bradycardia and arrhythmia which were observed by exposure to 20 ppm NO2 or more for 3 h were abolished by injection of atropine sulfate. ECGs were recorded following experimental formation of nitrite (NO-2) and nitrate (NO-3) in blood of normal rats by administration of NaNO2 solution, but no remarkable changes were observed on ECG. These results suggest that abnormal cardiac function observed during acute exposure to NO2 is attributable to changes in parasympathetic nervous activity and not to elevated NO2- and NO3- concentration in blood.

Animals↗

PubMed1994

Light-mediated conversion of nitrogen dioxide to nitric oxide by carotenoids.

Plants are more susceptible to the toxic effects of nitrogen dioxide when exposure takes place in the dark. Beta-carotene and other common carotenoids react with nitrogen dioxide in the dark to yield intermediate nitrosating agents consistent with the formation of nitrate esters. Simultaneous exposure of carotenoids to NO2 and light significantly reduced formation of nitrosating intermediates and resulted in the release of nitric oxide (NO) into the gas phase. Light-mediated reduction of NO2 to NO by carotenoids may be an important mechanism for preventing damage in plants exposed to NO2. The formation of nitrosating agents from the reaction of carotenoids with NO2 suggests that their ability to prevent nirosative damage associated with NO2 exposure in both plants and animals may be limited in the absence of light.

Animals↗

PubMed1987

Lipid peroxidation and antioxidative protection mechanism in rat lungs upon acute and chronic exposure to nitrogen dioxide.

This work was done to clarify the relation between the changes of lipid peroxidation and the activities of antioxidative protective enzymes in lungs of rats exposed acutely, subacutely, and chronically to nitrogen dioxide. It was confirmed that the activities of the antioxidative enzymes to protect cells from oxidative stress increased in an early phase, and then the activities decreased gradually. Lipid peroxides increased once in an early phase and then returned to the control level; thereafter, lipid peroxides increased gradually again. Lipid peroxidation as measured by ethane exhalation increased significantly with 0.04, 0.4, and 4 ppm nitrogen dioxide exposure for 9, 18, and 27 months, and a dose-response relationship was clearly observed. The temporal changes of lipid peroxidation varied inversely with that of the activities of antioxidative protective enzymes. From these results, it was suggested that the increments of antioxidative protective enzyme activities in an early phase were complementary effects to protect cells from damage by lipid peroxides which were increased by nitrogen dioxide exposure, and that the complementary effects are lost in later phases of life-span exposure. Finally, loss of such protective complementary effects might relate to some chronic diseases in lungs. Therefore, the temporal changes described above are important characteristics in chronic exposure of air pollutants.

Animals↗

PubMed2005

Detection of atmospheric nitrogen dioxide using a miniaturised fibre-optic spectroscopy system and the ambient sunlight.

A miniaturised fibre-optic spectrometer based system is presented for direct detection of one of the major atmospheric pollutants, nitrogen dioxide, by absorption spectroscopy using the ambient sunlight as light source. The detection system consists of a 10 cm collimator assembly, a fibre-optic cable and a portable diode-array spectrometer. The absorbance spectrum of the open-path is calculated using a reference spectrum recorded when the nitrogen dioxide (NO2) concentration in the atmosphere is low. The relative concentration of the pollutant is calculated normalising the detected spectra and subtracting the background broadband spectrum from the specific NO2 absorbance features, since the broadband spectrum changes according to atmospheric conditions and solar intensity. Wavelengths between 400 and 500 nm are used in order to maximise sensitivity and to avoid interference from other species. Calibration is carried out using Tedlar sample bags of known concentration of the pollutant. A commercial differential optical absorption spectroscopy (DOAS) system is used as a reference standard detection system to compare the results with the new system. Results show that detection of NO2 at typical urban atmospheric levels has been achieved using an inexpensive field based fibre-optic spectrometer and a readily available, easy to align, light source. In addition the new system can be used to get a semi-quantitative estimation of the nitrogen dioxide concentration within errors of 20%. While keeping the typical benefits of open-path techniques, the new system has important advantages over them such as cost, simplicity and portability.

Air Pollutants↗

PubMedDate not supplied

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.

Adolescent↗

PubMed2005

Characterization of a spatial gradient of nitrogen dioxide across a United States-Mexico border city during winter.

A gradient of ambient nitrogen dioxide (NO(2)) concentration is demonstrated across metropolitan El Paso, Texas (USA), a city located on the international border between the United States and Mexico. Integrated measurements of NO(2) were collected over 7 days at 20 elementary schools and 4 air quality monitoring stations located throughout the city during typical winter atmospheric conditions. Replicate passive monitors were co-located with chemiluminescence analyzers at the monitoring stations for two consecutive 7-day periods. The passive measurements correlated with the analyzer measurements (R(2)=0.74) with precision of 2.5+/-2.2 ppb. Nitrogen dioxide concentrations ranged from 11.0 to 37.5 ppb (mean 20.6+/-7.1 ppb). In a multivariate regression model, the site elevation and distances to a main highway and to an international port of entry from Mexico explained 81% of the variance in the passive measurements. The results of this pilot study indicate that proximity to vehicle-related sources of NO(2) and site elevation are key predictors for future, more detailed assessments of vehicle-related air pollution exposure in the El Paso region.

Air Pollutants↗

PubMed2006

Measurement of nitrogen dioxide in cigarette smoke using quantum cascade tunable infrared laser differential absorption spectroscopy (TILDAS).

Although nitrogen dioxide (NO(2)) has been previously reported to be present in cigarette smoke, the concentration estimates were derived from kinetic calculations or from measurements of aged smoke, where NO(2) was formed some time after the puff was taken. The objective of this work was to use tunable infrared laser differential absorption spectroscopy (TILDAS) equipped with a quantum cascade (QC) laser to determine if NO(2) could be detected and quantified in a fresh puff of cigarette smoke. A temporal resolution of approximately 0.16s allowed measurements to be taken directly as the NO(2) was formed during the puff. Sidestream cigarette smoke was sampled to determine if NO(2) could be detected using TILDAS. Experiments were conducted using 2R4F Kentucky Reference cigarettes with and without a Cambridge filter pad. NO(2) was detected only in the lighting puff of whole mainstream smoke (without a Cambridge filter pad), with no NO(2) detected in the subsequent puffs. The measurement precision was approximately 1.0 ppbVHz(-1/2), which allows a detection limit of approximately 0.2 ng in a 35 ml puff volume. More NO(2) was generated in the lighting puff using a match or blue flame lighter (29+/-21 ng) than when using an electric lighter (9+/-3 ng). In the presence of a Cambridge filter pad, NO(2) was observed in the gas phase mainstream smoke for every puff (total of 200+/-30 ng/cigarette) and is most likely due to smoke chemistry taking place on the Cambridge filter pad during the smoke collection process. Nitrogen dioxide was observed continuously in the sidestream smoke starting with the lighting puff.

Chemistry Techniques, Analytical↗

PubMed1981

[Blastomogenic action of low concentrations of nitrosodimethylamine, dimethylamine and nitrogen dioxide].

The round-the clock inhalation of the mixture of nitrosodimethylamine (NDMA), dimethylamine (DMA) and nitrogen dioxide, with NDMA concentrations varying within 0.66-0.0026 mg/m3, was followed by development of tumors in the kidney, liver, lungs and at other sites in albino nonbred rats, after a year of exposure. Application of DMA and nitrogen dioxide modified the carcinogenic effect of NDMA. In male rats, the blastogenic effect of the mixture was higher, as compared with that of inhalation of NDMA alone. NDMA inhalation resulted in a lower tumor yield in female rats.

Animals↗

PubMed1995

Validation of a simple method assessing nitric oxide and nitrogen dioxide concentrations.

Monitoring of nitric oxide (NO) and nitrogen dioxide (NO2) is a prerequisite for the clinical use of NO. Chemiluminescence, the reference method, cannot be used as a routine in clinical practice in view of its cost and other restraints. This study was performed to evaluate a device using an electrochemical method (Polytrons NO and NO2, Dräger). Forty-nine simultaneous measurements of NO and various oxides of nitrogen (NOx) concentrations by the two apparatus were performed. NO measurements by means of these two methods are very well correlated (r = 0.96; p < 10(-5)). The mean difference according to the method of Bland and Altman was 2.8 +/- 1.7 ppm, with the limits of agreement at -0.6 and +6.2 ppm (confidence interval of 95%). There was also a good correlation between measurements of NO2 obtained via Polytrons and NOx via chemiluminescence (r = 0.84; p < 10(-5)). However, NO2 measurements obtained via Polytrons may be insufficient to exclude potential toxicity of NO2 due to the inability to detect measurements in the ppb-range. This study demonstrates that devices designed for industrial purposes (Polytrons NO and NO2, Dräger) can be used for clinical purposes.

Administration, Inhalation↗

PubMed1995

In-vitro exposure of guinea pig main bronchi to 2.5 ppm of nitrogen dioxide does not alter airway smooth muscle response.

In order to investigate whether the oxidant airborne pollutant nitrogen dioxide (NO2) affects airway smooth muscle responsiveness, the contractile response of guinea pig main bronchi after in vitro exposure to 2.5 ppm of nitrogen dioxide was studied. Main bronchi were cannulated and exposed for 2 or 4 h to a constant flow of either NO2 or air. After exposure, bronchial rings were obtained and placed in a 37 degrees C jacketed organ bath filled with Krebs-Henseleit solution. Concentration-response curves were performed for acetylcholine (10(-9)-10(-3) M), substance P (10(-9)-10(-4) M), and neurokinin A (10(-10)-10(-5) M), and voltage-response curves (12-28 V) were performed for electrical field stimulation. There was no significant difference in either the smooth muscle maximal contractile response, or sensitivity between the bronchi exposed to NO2 and those exposed to air. We conclude that in vitro exposure to 2.5 ppm of NO2 does not alter airway smooth muscle responsiveness in guinea pigs.

Acetylcholine↗

PubMed2006

Photosensitized reduction of nitrogen dioxide on humic acid as a source of nitrous acid.

Nitrous acid is a significant photochemical precursor of the hydroxyl radical, the key oxidant in the degradation of most air pollutants in the troposphere. The sources of nitrous acid in the troposphere, however, are still poorly understood. Recent atmospheric measurements revealed a strongly enhanced formation of nitrous acid during daytime via unknown mechanisms. Here we expose humic acid films to nitrogen dioxide in an irradiated tubular gas flow reactor and find that reduction of nitrogen dioxide on light-activated humic acids is an important source of gaseous nitrous acid. Our findings indicate that soil and other surfaces containing humic acid exhibit an organic surface photochemistry that produces reductive surface species, which react selectively with nitrogen dioxide. The observed rate of nitrous acid formation could explain the recently observed high daytime concentrations of nitrous acid in the boundary layer, the photolysis of which accounts for up to 60 per cent of the integrated hydroxyl radical source strengths. We suggest that this photo-induced nitrous acid production on humic acid could have a potentially significant impact on the chemistry of the lowermost troposphere.

Atmosphere↗

PubMed1999

Nitrogen dioxide formation during inhaled nitric oxide therapy.

BACKGROUND: Nitrogen dioxide (NO2) is a toxic by-product of inhalation therapy with nitric oxide (NO). The rate of NO2 formation during NO therapy is controversial. METHODS: The formation of NO2 was studied under dynamic flows emulating a base case NO ventilator mixture containing 80 ppm NO in a 90% oxygen matrix. The difficulty in measuring NO2 concentrations below 2 ppm accurately was overcome by the use of tunable diode laser absorption spectroscopy. RESULTS: Using a second-order model, the rate constant, k, for NO2 formation was determined to be (1.19 +/- 0.11) x 10(-11) ppm-2s-1, which is in basic agreement with evaluated data from atmospheric literature. CONCLUSIONS: Inhaled NO can be delivered safely in a well-designed, continuous flow neonatal ventilatory circuit, and NO2 formation can be calculated reliably using the rate constant and circuit dwell time.

Administration, Inhalation↗