Summer in D.C. brings swarms of mosquitos, destructive micro-burst storms, and of course, smog. This year, the region has also experienced the worst air quality in recent memory, because of wildfire smoke. Officials are asking residents to help limit air pollution by driving less this month.

This summer there have already been 17 code orange days, when the air is considered unhealthy for sensitive groups, and there have been 3 code red days, when the air is unhealthy for everyone.

While much of the air pollution this summer has come from particulate matter drifting into the region from wildfires in Canada, there’s also plenty of homegrown pollution from the regions cars, trucks, and power plants. Chemicals from tailpipes and smokestacks interact in the presence of heat and sunlight, forming ground-level ozone, more familiarly known as smog.

As much as a quarter of those chemical ingredients that form smog come from vehicles. And because smog needs heat and light to form, it’s usually worst in the hottest days of summer — in other words, right about now.

“We’re focusing on August because typically that is one of the hottest months of the summer, and we usually see high levels of ground level ozone,” says Jen Desimone, managing director of Clean Air Partners and chief of the air program at the Metropolitan Washington Council of Governments.

Desimone says you should think about ways to get around without a car this month.

“Instead of driving or using single occupancy vehicles, use transit, take metro, take busses or trains. Residents can bike and they can walk as well when air quality is good.”

If you do need to drive, you can reduce your air pollution impact by combining errands into one trip, and by filling up your gas tank in the evening, and not topping off the tank. That’s because vapors emitted from the gas pump can react with heat and sunlight during the day to form smog.

Desimone also recommends trying to use less energy at home, to reduce the strain on the electric grid on hot days, and to reduce emissions from power plants.

“I know it’s uncomfortable and I know it’s hard, but just turning up your thermostat a couple of degrees will help,” she says.

Of course, changing when you pump your gas or how you organize errands is not going to solve our air pollution problem, but Desimone says small individual actions like this do make a difference, especially when combined with larger state or federal-level policies.

“We know that collectively all of the actions being taken do help to improve regional air quality,” Desimone says.