Capturing pollution characteristics in different air mass experimentally using an automatically directional air sampler

Pollution characteristics in air masses from different directions could be dissimilar and consequently have distinct impacts on human health; however, available studies did not provide separated results of pollution characteristics for air from different directions in one experiment when using traditional air samplers. Here, an Automatically Directional Air Sampler (ADAS) is developed and evaluated aiming at providing a new sampling approach for capturing and comparing hazardous air pollutants in different air masses. PM2.5 and particulate polycyclic aromatic hydrocarbons (PAHs, including 16 priority and 13 non-priority ones) are measured as targeted air pollutants in evaluating the performance of this new device. The time-weighted averages of pollution levels over the whole sampling duration using the ADAS were close to that using a traditional air sampler, but the former clearly captured distinct pollution characteristics such as pollution levels, composition profiles and potential sources of PAHs in air masses from different directions. The new device also provided an estimate of relative contributions of air pollution in different air trajectories. In the study site, air mass from the west had relatively high pollution levels, at 6.83ng/m3, but contributed to only 14% of the averaged 0.75ng/m3 during the sampling period. Sampling absorbents or channels can be modified in future to collect other air pollutants of interest. The experimental evidences of different pollution characteristics in different trajectories are important in identifying priority risk sources and developing pollution control strategies more efficiently.