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Title: The effect of ambient air pollution on airway function and respiratory symptoms in asthmatics and chronic bronchitics.
Author: Francis, Helen Claire.
ISNI:       0000 0001 3481 6989
Awarding Body: Manchester Metropolitan University
Current Institution: Manchester Metropolitan University
Date of Award: 1999
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A study was performed in the North West of England investigating the effects of air pollution on various measures of respiratory health in subjects with asthma and chronic bronchitis. The study consisted of three distinct phases: the collection of peak flow and symptom diary data during two summers and one winter period; analysis of the data to investigate any interaction between aero-allergen levels and pollution; and repeated measurements of asthmatic bronchial hyperreactivity (BHR) on days of differing pollution levels. The pollutants investigated were ozone, sulphur dioxide, nitrogen dioxide and black smoke (second summer only) and levels of pollens and spores were also recorded. A total of 199 peak flow rate/symptom diaries were collected, representing over 4700 person days of data. Seventy five subjects returned adequate peak flow diaries during the first summer compared with 50 subjects in winter and 63 subjects in the second summer. Pollution and allergen interaction analysis was performed using data from 35 subjects found to be methacholine reactors. Thirty eight subjects participated in the repeat bronchial reactivity testing phase of the study (a total of 109 tests were performed). Daily mean pollution levels were below World Health Organisation (WHO) guidelines throughout the study. Phase 1: Summertime pollution (summer 1991) was found to be associated with small but significant adverse effects on respiratory health, despite levels of pollution being below WHO guidelines. The associations were strongest for ozone. These adverse effects could not be demonstrated during the winter or second summer. Levels of ozone were considerably lower during the latter two periods of data collection, suggesting that there may be a "no effect" level of ozone exposure. Phase 2: Adverse changes in peak flow in association with increases in allergen level (spore count) were found to be larger the higher the subjects' ozone exposure on the previous day, suggesting that ozone exposure may have potentiated the effect of the allergen. However, the magnitude of the enhanced response was small. Phase 3: Methacholine bronchial hyperreactivity was found to increase with rising levels of sulphur dioxide and nitrogen dioxide and these changes were not related to variations in pre-challenge spirometry. Associations were strongest for nitrogen dioxide, accounting for 10% of the variation in within-subject BHR. In conclusion, this study was able to demonstrate adverse health effects of ambient air pollution. Although the magnitude of the changes detected was small, they occurred at levels of pollution below WHO guidelines. Adverse effects of pollution on peak flow and symptom reporting were only found for the first summer of data collection, during which a high peak of ozone exposure occurred. An interaction between pollution and allergen was also found during this first summer. Changes in bronchial reactivity with pollution were detected despite the low levels pollution that occurred during the second summer.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available