Among the chemicals frequently occurring in polluted air at higher than normal concentrations are sulphur oxides and nitrogen oxides In some cases hydrochloric acid vapour and mists of phosphoric acid and other acids may also be present
Among the chemicals frequently occurring in polluted air at higher than normal concentrations are sulphur oxides and nitrogen oxidesIn some cases hydrochloric acid vapour and mists of phosphoric acid and other acids may also be present