The abysmal air quality predicted for today has prompted the Department of Environmental Quality to ask drivers to observe a voluntary "No Drive Day" in Davis and Salt Lake counties.
Ozone levels, which cause the brownish haze that hovers in the atmosphere, are expected to be high. Smog consists primarily of ozone, which is produced by vehicle emissions in the bright sun.
The department has asked that people consider taking a bus, sharing a ride with friends or telecommuting if they have to work.
For those who must drive, health officials recommend consolidating errands and buying gas in the evening. Ozone levels usually are low in the morning but increase in the afternoon. Officials also suggest putting off any projects involving small engines, paints, degreasers and solvents.
Department officials warn that smog can cause various respiratory problems such as reduced lung function, as well as irritated eyes and nasal passages, and a reduced resistance to colds and infections.