It is a brownish-yellow hazy cloud caused when heat and sunlight react with various pollutants emitted from industry, cars, pesticides and oil based home products. Smog is a year-round problem but most smog watches and alerts occur from May to September, especially on hot days. Ground-level ozone is harmful to humans,animals and plants. Ground level ozone is formed through a complex reaction involving hydrocarbons, nitrogen oxides, and sunlight. Ground level ozone can inflame breathing passages, decreasing the lung's working capacity.
Symptoms can include shortness of breath, pain when inhaling deeply, wheezing and coughing.
Ground level ozone can cause eye and nose irritation. It can dry out the protective membranes of the nose and throat and interfere with the body's ability to fight infection increasing susceptibility to illness. High levels of ground level ozone on Smog Alert Days can result in increased emergency department visits, hospital admissions and, in severe cases premature death. Fine Airborne Particles Fine airborne particles are a mixture of solid particles and liquid droplets that vary in size. Fine airborne particles come from many sources, including industrial emissions, wind-blown dust from construction sites and roads, and vehicle exhaust.