This dataset contains direct infusion ultra-high resolution mass spectrometry measurements made at the Institute of Atmospheric Physics land station, Beijing (IAP-Beijing) site during the summer and winter APHH-Beijing campaign for the Atmospheric Pollution & Human Health in a Chinese Megacity (APHH) programme. Daily quartz microfiber filters were collected with a Tisch high volume sampler. The extracted organic fraction of the collected PM2.5 particles was analysed using an LTQ Orbitrap Velos mass spectrometer with electrospray ionisation to obtain high resolution mass spectra which enable the assignment of molecular formulae to the detected masses. For both seasons, 10 filters were analysed, containing the 5 filters with the highest and lowest mass loadings for each season. The files names are labeled according to the ID of the analysed filter. All dates and times are given in Beijing local time.

This dataset contains both the concentration of PM2.5 in ambient air sampled at a height of 8 metres and the concentration of water-soluble Silicon found in the PM2.5 samples resulting from the analysis by coupled plasma - optical emission spectrometry (ICP-OES). The PM2.5 samples were collected in the Institute of Atmospheric Physics, Chinese Academy of Sciences, China in August 2018 and January 2019. The data was collected to support the study of atmospheric chemistry and processes involving Silicon (Si) containing fine particles, which potentially contribute to atmospheric pollution. These data were collected as part of the Silicon-containing secondary organic aerosols in ambient air (Si-SOA) Natural Environment Research Council (NERC) funded project.