Fine particles and peak flow in children: Acidity versus mass

We assessed the impact of summertime haze episodes on twice daily peak flow measurements of children in Philadelphia, Pennsylvania. Height adjusted pe ak flows a ere regressed on weather and air pollution concentrations. Lower morning peak flows were associated with exposure to inhalable particulate matter (-2.94 liters/minute/18 mu g/m(3), 95% confidence limits (CL) = -0.5 6, -5.33), and line sulfate particles (-2.44 liters/minute/8 mu g/m(3), 95% CL = -0.36, -4.51). Particle-strong acidity and the coarse particle mass w ere weakly associated with lower peak flow, Acutely lower peak flows in chi ldren were associated with fine sulfate particles, but only weakly with the acidity of the fine particles.