Air pollution has been linked to dementia, according to a study published Wednesday in BMJ Open. The study looked at the addresses of 130,978 people in London ages 50 to 79 years old who were healthy at the start of the study. Researchers tracked addresses with estimated yearly exposures to pollutants like nitrogen dioxide and fine particulate matter over seven years. In that time, 1.7 percent of patients were diagnosed with dementia. In polluted areas, patients were 40 percent more likely to develop dementia. The study found that car exhaust was the leading correlate between dementia and pollution, and that the link remained even after controlling for other factors like heavy drinking and smoking. The study is the latest linking air pollution with dementia: In April, a study found that even babies less than a year old showed signs of Alzheimers in Mexico City.