Figure 2.20: Percentage of measured one-hour and eight-hour average CO concentrations within air quality categories on Riccarton Road, Christchurch

Text description of figure

There are two charts measuring CO concentrations in Riccarton Road, Christchurch, in 1993, 1996, and 2001. The first chart measures one-hour concentrations of CO. Readings have improved considerably since 1993, and in 2001 over 90% of measurements were “Good” or “Excellent”. The second chart shows 8-hour concentrations of CO. Concentrations were very poor in 1993, with more than 60% of measurements being at “Alert” level or over the guideline. Measurements improved in 1996, and by 1997 only 10% of measurements were over the “Acceptable” level.