On hot summer days, pollution from cars and other gas-powered engines along with chemicals in paints and aerosol sprays can create unhealthy levels of smog. There are things you can do to help keep the air healthy when the temperature rises. Skip mowing or using a leaf blower for a day or two, if they’re gas powered. Choose water-based latex paints for your painting projects. On smoggy days especially, avoid using oil-based paints and varnishes. And consider leaving your car at home. Commute by transit, carpool or bike to work.