<p>Our work explores the impact of two important dimensions of land system changes, land use and land cover change (LULCC) and direct agricultural reactive nitrogen (N<sub>r</sub>) emissions from soils, on ozone (O<sub>3</sub>) and fine particulate matter (PM<sub>2.5</sub>) air quality over contemporary (1992 to 2014) time scales. We account for LULCC and agricultural N<sub>r</sub> emissions changes with consistent remote sensing products and new global emission inventories, respectively, estimating their impacts on global surface O<sub>3</sub> and PM<sub>2.5</sub> concentrations and N<sub>r</sub> deposition using the GEOS-Chem global chemical transport model. Over this time period, our model results show that agricultural N<sub>r</sub> emission changes cause reduction of annual mean PM<sub>2.5</sub> level over Europe and northern Asia (up to −2.1 μg m<sup>−3</sup>), while increasing PM<sub>2.5</sub> level India, China and eastern US (up to +3.5 μg m<sup>−3</sup>). Land cover changes induce small reductions in PM<sub>2.5</sub> (up to −0.7 μg m<sup>−3</sup>) over Amazonia, China and India due to reduced biogenic volatile organic compounds (BVOC) emissions and enhanced deposition of aerosol precursor gases (e.g. NO<sub>2</sub>, SO<sub>2</sub>). Agricultural N<sub>r</sub> emission changes only lead to minor changes (up to ±0.6 ppbv) in annual mean surface O<sub>3</sub> level, mainly over China, India and Myanmar. Meanwhile, our model result suggests a stronger impact of LULCC on surface O<sub>3</sub> over the time period Across South America, the combination of changes in dry deposition and isoprene emissions results in −0.8 to +1.2 ppbv surface ozone changes. The enhancement of dry deposition reduces surface ozone level (up to −1 ppbv) over southern China, eastern US and central Africa. The enhancement of soil NO<sub>x</sub> emission due to crop expansion also contribute to surface ozone changes (up to +0.6 ppbv) over sub-Saharan Africa. In certain regions, the combined effects of LULCC and agricultural N<sub>r</sub> emission changes on O<sub>3</sub> and PM<sub>2.5</sub> air quality can be comparable (> 20 %) to that of anthropogenic emission changes over the same time period. Finally, we calculate that the increase in global agricultural N<sub>r</sub> emissions leads to a net increase in global land area (+3.67 × 10<sup>6</sup> km<sup>2</sup>) that potentially faces exceedance in critical N<sub>r</sub> load (> 5 kgN ha<sup>−1</sup> yr<sup>−1</sup>). Our result demonstrates the possible impacts of contemporary LULCC and agricultural N<sub>r</sub> emission changes on PM<sub>2.5</sub> and O<sub>3</sub> air quality, which also implies the potential importance of land system changes on air quality over multi-decadal timescales.</p>