The Interaction Between Ambient Particulate Matter Exposure And Physical Exercise On Lung Function And Biomarkers Among Adults

Exposure to ambient particulate matter could reduce lung function,while causing inflammatory responses and oxidative stress.Physical exercise could improve lung function and lead to the changes in biomarkers.Exploring the interaction between particulate matter and physical exercise on health is the popular research issues.However,related studies were limited and findings were inconsistent.In this study,we used exposure dose to characterize the combined effect of particulate matter and exercise.We conducted the cardiopulmonary exercise testing to establish a model between heart rate and ventilation to predict the individual realtime ventilation.In cross-over study,we monitored the concentration and estimated the exposure doses of the particulate matter less than 1 μm（PM₁）,fine particulate matter(PM_2.5),coarse particulate matter(PM₁₀),and ultrafine particles（UFP）.We used heart rate monitoring to evaluate the physical exercise intensity.In addition,we measured lung function and fractional exhaled nitric oxide（FeNO）,as well as biomarkers of inflammation and oxidative stress in blood,urine,and exhaled breath condensate.Then we explored the independent and interactive associations between particulate matter exposure and physical exercise on lung function and biomarkers.The main findings were as follows:（1）We have established the model between heart rate and ventilation for Chines young adults,which was Log（ventilation）（L/min）=0.007×Heart rate（bpm）+0.585.The coefficient of determination（R²）of the model was 0.84.The R² and root mean square error（RMSE）of cross-validation was 0.78 and 0.13,which indicated the good extrapolation of the model.Based on this model,we have estimated the exposure dose to characterize the co-exposure of particulate matter and physical exercise.（2）Physical exercise could weaken or even reverse the harmful effects of particulate matter exposure on lung function.Every interquartile distance（IQR）increase in exposure dose of PM₁₀,the forced expiratory flow at 75%（FEF75）decreased by 0.1%in the non-exercise group,while the FEF75 increased by 5.5%in the exercise group.（3）Physical exercise attenuated the airway inflammation induced by particulate matter.However,it could exacerbate the association between particulate matter exposure and inflammatory cells as well as malondialdehyde（MDA）.Every IQR increase in PM₁₀,the FeNO of the non-exercise group increased by 0.2%,while the FeNO decreased by 0.2%in the exercise group.Each IQR increase in PM₁,the monocytes and basophils decreased by 4.3%and 5.8%in the non-exercise group,respectively,and MDA in urine increased by 10.4%,while the related biomarkers increased by 4.4%,1.4%,and 14.8%in the exercise group,respectively.（4）We observed the strongest effects of particulate matter with different sizes on lung function and biomarkers of airway inflammation occurred in different regions of the respiratory tract.PM₁ and PM₁₀ showed the strongest effects in the tracheo bronchial（TB）and extrathoracic（ET）region,respectively.PM_2.5 showed the strongest effects in the ET or TB region.This study could contribute new evidence to explore the interaction between particulate matter exposure and physical exercise on health,and further provide scientific basis and support for the public to engage in outdoor exercise.