The aerosol data available through HITRAN are described in the following readme files:
Aerosol data and documentation are accessible directly from the HITRAN FTP server. The data can also be accessed from the command line with username "anonymous" and your email address as the password:
ftp to cfa-ftp.harvard.edu
user = anonymous
password = e-mail address
In the directory /pub/HITRAN2012/Aerosols-2016 you will find a number of files and folders, which contain both data and software for accessing these files. Users are referred to the readme documents above for a complete description of the file structure.