def get_species_units(input):
    """
    Retrieve units for GEOS-CF species and derived values
    """
    if 'NOy/' in input:
        units = 'unitless'
    elif 'pm25' in input:
        units = '$\mu$g m$^{-3}$'
    elif 'Dust' in input:
        units = '$\mu$g m$^{-3}$'
    elif 'NOy' in input:
        units = 'ppbv'
    else:
        units = 'v/v'
    return units