Can acid rain damage car paint?

Rain that has absorbed airborne pollutants can become acidic, and as droplets evaporate the acids and contaminants concentrate on the paint. Repeated exposure, especially followed by hot sun, can leave etched spots on horizontal panels such as the hood, roof and trunk. Rinsing the car after rain in polluted areas, drying it and keeping a protective layer on the paint reduce the risk. Etching that has already formed may need polishing.