Effect of Personal Exposure to PM2.5 on Respiratory Health in a Mexican Panel of Patients with COPD

BACKGROUND Air pollution is a problem, especially in developing countries. We examined the association between personal exposure to particulate matter with an aerodynamic diameter less than 2.5 µm (PM2.5) on respiratory health in a group of adults with chronic obstructive pulmonary disease (COPD). METHODS All participants resided in Mexico City and during follow-up, personal exposure to PM2.5, respiratory symptoms, medications, and daily activity were registered daily. Peak expiratory flow (PEF) was measured twice daily, from February through December, 2000, in 29 adults with moderate, severe, and very severe COPD. PEF changes were estimated for each 10 µg/m³ increment of PM2.5, adjustment for severity of COPD, minimum temperature, and day of the sampling. RESULTS For a 10-µg/m³ increase in the daily average of a two-day personal exposure to PM2.5, there was a significant 33% increase in cough (95% CI, range, 5-69%), and 23% in phlegm (95% CI, range, 2-54%), a reduction of the PEF average in the morning of -1.4 L/min. (95% CI , range, -2.8 to -0.04), and at night of -3.0 L/min (95% CI, range, -5.7 to -0.3), respectively. CONCLUSIONS Exposure to PM2.5 was associated with reductions in PEF and increased respiratory symptoms in adults with COPD. The PEF reduction was observed both at morning and at night.