nitrogen-dioxide and Airway-Obstruction

Several studies have linked air pollution by nitrogen dioxide (NO(2)) with increased hospital admissions for asthma in children. Exacerbations of asthma in children are often precipitated by upper respiratory infections. It is therefore possible that NO(2) increases the risk of airways obstruction when asthmatic children develop upper respiratory infections.. To test this hypothesis a sample of 114 asthmatic children aged 7-12 years were followed for a total of up to 13 months. Probable upper respiratory infections were identified by consensus review of daily symptom diaries, and episodes of airways obstruction from serial records of peak expiratory flow (PEF). Personal exposures to NO(2) were measured with Palmes tubes that were changed weekly. Generalised estimating equations were used to assess the relative risk (RR) of an asthmatic exacerbation starting within seven days of an upper respiratory infection according to estimated NO(2) exposure during the one week period from two days before to four days after the onset of the infection.. The children were followed for an average of 34 weeks during which 318 upper respiratory infections and 224 episodes of reduced PEF were diagnosed. PEF episodes were much more likely to occur in the seven days following the onset of an upper respiratory infection than at other times. Estimated exposures to NO(2) at the time of infections were generally low (geometric mean 10.6 microg/m(3)). Compared with exposures of < or = 8 microg/m(3), exposures of >28 microg/m(3) were associated with a RR of 1.9 (95% confidence interval 1.1 to 3.4) for the development of an asthmatic episode within seven days of an infection.. The findings give some support to the hypothesis that NO(2) increases the risk of asthmatic exacerbations following respiratory infections, even at relatively low levels of exposure. Further studies in populations with higher exposures would be useful.

Topics: Air Pollutants; Airway Obstruction; Asthma; Child; England; Female; Humans; Longitudinal Studies; Male; Nitrogen Dioxide; Oxidants, Photochemical; Peak Expiratory Flow Rate; Respiratory Tract Infections

To identify characteristics associated with respiratory symptoms due to an episode of air pollution.. Mail survey.. In October 1992, the population of the city of Winnipeg was exposed to elevated levels of particulate matter (total and <10 microm size), carbon monoxide, nitrogen dioxide, and volatile organic compounds due to smoke from adjacent fields where farmers were burning agricultural residue (straw and stubble).. We surveyed 428 participants in the ongoing Lung Health Study (35 to 64 years old, both sexes) with mild to moderate airways obstruction (mean FEV1 percent predicted 73+/-12%), and a high level of airways hyperreactivity (23% of men and 37% of women).. While 37% of subjects were not bothered by smoke at all, 42% reported that symptoms (cough, wheezing, chest tightness, shortness of breath) developed or became worse due to the air pollution episode and 20% reported that they had breathing trouble. Those with symptoms were more likely to be female than male and were more likely to be ex-smokers than smokers. Subjects with asthma and chronic bronchitis were also more likely affected. The degree of airways obstruction and the level of bronchial hyperresponsiveness were not associated with increased susceptibility.. Gender, smoking habit, and respiratory symptoms but not bronchial hyperresponsiveness or the degree of airways obstruction are factors influencing susceptibility to symptoms due to air pollution in adult smokers and former smokers.

Topics: Adult; Agriculture; Air Pollutants; Air Pollution; Airway Obstruction; Asthma; Bronchial Hyperreactivity; Bronchitis; Carbon Monoxide; Chest Pain; Chronic Disease; Cough; Disease Susceptibility; Dyspnea; Female; Forced Expiratory Volume; Humans; Male; Manitoba; Middle Aged; Nitrogen Dioxide; Organic Chemicals; Respiration; Respiratory Sounds; Sex Factors; Smoke; Smoking

The objective of the investigation was to test the hypothesis that exposure to nitrogen dioxide (NO2) has a causal influence on the occurrence of bronchial obstruction in children below 2 years of age.. A nested case-control study with 153 one-to-one matched pairs was conducted within a cohort of 3754 children born in Oslo in 1992/93. Cases were children who developed > or = 2 episodes of bronchial obstruction or one episode lasting >4 weeks. Controls were matched for date of birth. Exposure measurements were performed in the same 14-day period within matched pairs. The NO2 exposure was measured with personal samplers carried close to each child and by stationary samplers outdoors and indoors.. Few children (4.6%) were exposed to levels of NO2 > or = 30 microg/m3 (average concentration during a 14-day period). In the 153 matched pairs, the mean level of NO2 was 15.65 microg/m3 (+/-0.60, SE) among cases and 15.37 (+/-0.54) among controls (paired t = 0.38, P = 0.71).. The results suggest that NO2 exposure at levels observed in this study has no detectable effect on the risk of developing bronchial obstruction in children below 2 years of age.

Topics: Air Pollution, Indoor; Airway Obstruction; Female; Follow-Up Studies; Humans; Incidence; Infant; Infant, Newborn; Male; Nitrogen Dioxide; Norway; Oxidants, Photochemical; Retrospective Studies; Risk Factors

The aim was to compare the peak expiratory flow (PEF) of welders and non-welders over a 12 hour period from the start of work on Monday.. The two study groups consisted of 20 welders and 20 non-welders, all men who had essentially never smoked, with no significant difference in age, height, ethnicity, or baseline spirometry between the groups. The PEF was measured for each welder before the start of work and 15 minutes, 30 minutes, and 1, 2, 4, 7, and 12 hours after the start of welding. The same method was applied to the non-welders, for whom a proxy time for the start of welding was used.. The percentage change in baseline PEF was calculated for each subject at each of the recording times. The welder and non-welder group means for these results were significantly different at 15 minutes (p = 0.028). Also, the group mean for maximum fall in PEF (at any of the recording times during the 12 hour period) was significantly greater for the welders (p = 0.011). 50% of the welders (10/20), but only 5% of the non-welders (1/20), experienced a fall in PEF in excess of 5% (p = 0.0046). 25% of the welders (5/20) experienced drops of greater than 5% within the first 15 minutes.. The results are suggestive of an immediate type reaction in welders, similar to that seen in some cases of occupational asthma, although not so severe. Studies to determine if these reactions reflect non-specific bronchial hyper-responsiveness would be useful. It is recommended that future studies also undertake breathing zone measurements to relate the response to particular constituents of the welding plume, especially the gases ozone and nitrogen dioxide.

Topics: Adult; Airway Obstruction; Cross-Sectional Studies; Humans; Lung; Male; Nitrogen Dioxide; Occupational Exposure; Ozone; Peak Expiratory Flow Rate; Time Factors; Welding

Topics: Accidents, Occupational; Airway Obstruction; Animals; Bronchitis; Cricetinae; Fires; Humans; Infections; Lung Diseases, Obstructive; Nitrogen Dioxide; Rabbits; Rats