Variable
sulphate_total_2
sulphate_total_0
sulphate_total_1
pm1_mass
pm10_mass
chloride_2
chloride_1
chloride_0
potassium_1
potassium_0
potassium_2
sodium_0
ammonium_2
calcium_2
calcium_0
calcium_1
sodium_2
pm25_mass
nitrate_2
nitrate_1
nitrate_0
ammonium_0
ammonium_1
sodium_1
magnesium_2
magnesium_0
magnesium_1