Living near a highway seems to increase the risk of developing rheumatoid arthritis, which affects about one per cent of the U.S. population, a new study suggests. Environmental pollutants which increase inflammation, like cigarette smoke, have been shown to up the risk; car and truck exhaust seem to have a similar affect, the New York Times reports. Researchers looked at the records of 90,297 women enrolled in a large health study from 1976 to 2004, 687 of whom developed arthritis. Using the location of their homes in 2000, they calculated the distance each lived from roads with over two lanes of traffic. After controlling for age, cigarette smoking, oral contraceptive use and other variables, the team found that women who lived within 55 yards of a big road had a 31 per cent increased risk for rheumatoid arthritis, compared with those living over 220 yards away. The study appears online in Environmental Health Perspectives.