The Bay Area Air Quality Management District announced that today will be a Spare the Air Day, the fourth consecutive since Saturday and the ninth for the summer season.

Commuters are urged to consider taking public transit or carpooling, but there’s no free transit being offered. The district, a regional agency covering the nine-county Bay Area, announces Spare the Air Days when air-quality forecasts show an unhealthy concentration of ground-level ozone, or smog. Visit www.sparetheair.org for more information.