Halfway through today's Spare the Air day, Sacramento-area air quality officials announced that Thursday (July 12) will be a Spare the Air day, too.

The Spare the Air declarations are associated with high temperatures and the corresponding increase in ground-level ozone pollution — of which auto exhaust is a large contributor.

Therefore, people are asked to drive less, carpool and use public transit. As an incentive, rides are free on Unitrans and Yolobus on Spare the Air days.

As temperatures started soaring this week, so too did the air quality index — the higher the number, the worse the quality.

Sacramento-area air has been in the range of "unhealthy for sensitive groups" since Monday (July 9), when the index hit a regional high of 111. The index hit a regional high of 122 on Tuesday (July 10), and the forecast for today and Thursday (July 11 and 12) is 137.

Anything from 101 to 150 is “unhealthy for sensitive groups,” and any forecast of 127 or higher triggers a Spare the Air.

The declaration comes with a number of advisories, mostly aimed at reducing auto emissions:

• Park your car or drive less (perhaps by combining all your errands into one session). Limit your driving to the morning hours when pollution levels are low. Similarly, if you are biking or walking, you should do so in the morning hours — to limit your exposure to unhealthy air.
• Carpool to work (or work from home, if you can), and to sports and recreation activities.
• Take public transit (rides are free on Unitrans, Yolo Bus and the North Natomas shuttle).
• Refuel your car in the evening — and do not top off.
• Avoid the use of consumer spray products (such as hair spray, furniture polish, cooking spray and bathroom cleaners).
• It’s OK to barbecue, but do not use charcoal lighter fluid.
• Curtail the use of gas-powered gardening equipment.