Median deployment length to Iraq or Afghanistan was 13.0 10.3, 17.5 months and the median time since deployment was 4.2 2.7, 7.7 years. ...During deployment, veterans reported exposure to dust and sand 70.8 , smoke from burn pits 66.7 , vehicle exhaust 83.3 , and regional air pollution 26.0 on most days or daily. ...