EBC stored at -70oC will be analysed for 8-isoprostane, GROalpha, MCP1, eotaxin and MDC levels concentrations in batches. We will use 96-well polystyrene microplates coated with murine monoclonal antibodies against human 8 isoprostane, GRO alpha, MCP1, eotaxin and MDC levels. The levels of these markers in EBC will be measured in duplicates by sandwich enzyme immunoassay (R & D Systems, Minneapolis, MN, USA) according to instructions provided by the manufacturer.