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Effect of nitrous acid on lung function in asthmatics: a chamber study
W S Beckett1, M B Russi, A D Haber
1John B. Pierce Laboratory, Yale University School of Medicine, New Haven, CT 06510, USA.
Environmental Health Perspectives
|April 1, 1995
Summary
Exposure to nitrous acid (a common indoor air pollutant) slightly reduced lung function and increased symptoms in mild asthmatics. This highlights the need to consider nitrous acid
Area of Science:
- Environmental Health
- Respiratory Medicine
- Toxicology
Background:
- Nitrous acid (HONO) is an indoor air pollutant from combustion sources like gas stoves.
- Existing nitrogen dioxide (NO2) assays may conflate HONO exposure and effects.
- Understanding HONO's independent respiratory effects is crucial for accurate indoor air quality assessment.
Purpose of the Study:
- To isolate and assess the respiratory effects of nitrous acid exposure in adults with mild asthma.
- To differentiate HONO's health impacts from other nitrogen oxides.
Main Methods:
- Double-blinded crossover chamber study involving 11 mildly asthmatic adults.
- 3-hour exposure to 650 ppb nitrous acid or filtered air, with intermittent moderate exercise.
- Measurement of respiratory symptoms, exercise parameters, and post-exercise spirometry.
Main Results:
- A statistically significant decrease in forced vital capacity (FVC) occurred after nitrous acid exposure.
- The reduction in FVC was most pronounced 25 and 85 minutes post-exposure.
- Subjects reported significantly higher aggregate respiratory and mucous membrane irritant symptoms.
Conclusions:
- Nitrous acid exposure at 650 ppb for 3 hours causes slight alterations in lung mechanics in asthmatics.
- This exposure level does not induce significant airflow obstruction.
- Mild irritant symptoms are produced, emphasizing HONO's role as an indoor respiratory irritant.