Joshua Tree National Park: Air Quality 10-day ChartsOzone Data Collected at the Black Rock Monitoring Site
Ozone: 1-hour and 8-hour average concentrations
The chart below plots both the 1-hour and running 8-hour average ozone concentration, but only the 8-hour average should be used to compare with the standard. The standard is exceeded when the 8-hour concentrations reach or go above 75 parts per billion, as denoted by the line with the label NAT'L AMBIENT AIR QUALITY STANDARD. The background of the chart is color coded and relates to the EPA National Ambient Air Quality Standard for ozone, which is designed to protect human health.