"Aerosol loading" refers to the amount of particles or droplets suspended in the air, such as dust, pollution, or other tiny substances. It measures the concentration or density of these particles in the atmosphere. Full definition
In summary, an increase in atmospheric aerosol load decreases air quality and reduces the amount of solar radiation reaching the surface. (ipcc.ch)
The Hadcm3 model has calculated the largest increase in temperature which may be attributed to the reduction of aerosol load (40 %) over the period 1990 - 1999 somewhere in NE Europe, other models do that more in Southern Europe. (realclimate.org)
Bourassa, A.E., A. Robock, et al. 2012: Large volcanic aerosol load in the stratosphere linked to Asian monsoon transport. (data.giss.nasa.gov)