**6.2 Agriculture connections with aerosols**

There are two major ways that agriculture contributes to aerosols and their effects. One is by direct generation of primary aerosols. The second mode is indirectly, by generation of precursor gases. Precursors can undergo chemical reactions that produce secondary aerosols and other GHGs. Incomplete combustion of agricultural biomass, and fossil fuels by agricultural machinery for example, liberates primary aerosols (BC, OC); precursor gases (CO, SO2, NOx); as well as non-methane volatile organic compounds (NMVOCs) [42]. Precursors may also arise via manure management (e.g., NOx), fertilizer use (e.g., NH3), and pesticide applications. In the aquatic ecosystem, pesticides were blamable for 81%, 87%, and 96% of the detected exceedances of the acute risk threshold (ART) related to fish, invertebrates, and algae, respectively [67].
