Acute Health Effects of Ozone Exposure

The investigators will conduct a randomized controlled human exposure crossover study among 32 healthy young adults in Shanghai, China. Each subject will be exposed twice: once to clean air and once to 200 ppb ozone in a chamber for 2 hours. During the 2-hour exposure, each subject will be requested to alternate 20 minutes of rest and 10 minutes of exercise on a treadmill. The exercise workload will be adjusted to achieve the targeted ventilation of 25 ~ 27 L/min(approximately equal to 15 ~ 18L/min/m2 body surface area). Ozone will be generated by a silent electric discharge method (HTU-500, AZCO Industries Ltd., Canada) and introduced into the chamber. The temperature and relative humidity in the chamber will be maintained at 22±1℃ and 55%±5%, respectively. Health examinations will be conducted immediately prior to exposure, immediately after exposure, 2 hours after exposure and again the next morning. Health examinations include symptom questionnaire, skin tests, spirometry, and Holter monitoring. We plan to collect blood, buccal, urine, nasal secretion, saliva, exhaled breath condensate, sebum, and D-squame samples.

Inclusion criteria

• Living in Shanghai during study period;
• Ability to complete the exercise to achieve the ventilation of 15 to 18 L/min/m2 body surface area;
• Body mass index >18.5 and ≤30.0 (30 is the lower limit for class 2 obesity for Chinese).

Exclusion criteria

• Smoking and alcohol abuse;
• Current drug and dietary supplements intake;
• Subjects with allergic diseases, such as allergic rhinitis, allergic asthma, and atopy;
• Subjects with cardiovascular diseases, such as congenital heart disease, pulmonary heart disease, and hypertension;
• Subjects with respiratory diseases, such as asthma, chronic bronchitis, and chronic obstructive pulmonary disease;
• Subjects with chronic diseases, such as diabetes, chronic hepatitis, and kidney disease;
• Subjects who have a history of major surgery;
• Abnormal spirometry (FEV1 and FVC ≤ 75% of predicted and FEV1/FVC ≤ 0.65);
• Abnormal baseline 12-lead resting electrocardiogram;
• Abnormal blood index, such as cell counting, blood lipids, and glutamic-pyruvic transaminase (GPT).