The working group is primarily concerned with tropospheric chemistry and the influence of anthropogenic (e.g. air traffic) and natural factors on the environment.(e.g. air traffic) and natural (e.g. desert dust) emissions on the composition of the air and their effect on the climate. Increasing attention is also being paid to the chemistry of the condensed phase, particle formation and photochemistry in cloud droplets, long-range transport and the atmospheric degradation of pesticides and semi-volatile chemicals. Members of the working group also play a key role in the GDCh/DECHEMA/DBG Joint Committee on Chemistry, Air Quality and Climate (photooxidants, halogenated hydrocarbons) and in the DECHEMA, KRdL and GDCh expert group on particulate matter.