Differences between PM(2.5) chemical sources at semi-closed transport environments: comparing bus depots and metro platforms.

PM 2.5 in bus depots and metro stations is dominated by locally derived sources, with combustion emissions at depots and metal wear at metro stations, revealing distinct pollution profiles.

• Why it matters: Understanding source-specific contributions in semi-closed transport environments is crucial for developing effective air quality control strategies and protecting public health.
• What they did: Positive matrix factorization was used to analyze chemical composition and trace elements at one bus depot and two metro stations, identifying seven sources at the depot and multiple sources at stations.
• The result: Findings highlight the need for targeted interventions, such as filtration and source control, tailored to the specific emission profiles and particle characteristics of each environment.