The research, involving more than 200,000 people in Scotland, found an increase in exposure to nitrogen dioxide in particular was associated with a higher number of people being admitted to hospital for behaviour disorders and mental illnesses.
In all, 202,237 people aged 17 and above were included in the research, which was published in the open access journal BMJ Open.
Their health and hospital admissions for cardiovascular, respiratory, infectious diseases, mental illnesses or behaviour disorders were tracked from Public Health Scotland data.
They were linked to levels of four pollutants from road traffic and industry: nitrogen dioxide (NO2); sulphur dioxide (SO2); particulate matter diameter of at least 10μm (PM10); and small particulate matter of 2.5μm or less (PM2.5).