Table 3.
Exposure reduction scenarios for near-roadway exposure, regional NO2 and O3, and corresponding reduction in childhood asthma cases attributable to near-roadway pollution exposure (based on total of 320,500 children with asthma in LAC).
| Scenarios | Change considered | Change in exposure from baseline | Hypothesized new population exposure | Change in prevalent casesa (95% CI) | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| No. | Percent (95% CI) | |||||||||
| Scenario 1 (reduction to background) | ||||||||||
| Traffic proximity | –100% | –17.8% | 0% | Decrease by 27,100 (4,900, 51,200) | 8% (2%, 16%) | |||||
| Dispersion-modeled near-roadway NOx | –100% | –2.56 ppb | 0 ppb | Decrease by 39,800 (6900, 65,600) | 12% (2%, 20%) | |||||
| NO2 | Decrease to background levels | –19.3 ppb | 4 ppb | — | — | |||||
| O3 | Decrease to background levels | –3.03 ppb | 36.3 ppb | — | — | |||||
| Scenario 2 (reduced regional pollution and near-roadway exposure) | ||||||||||
| Traffic proximity | –3.6% | –3.6% | 14.2% | Decrease by 5,900 (1,000, 11,800) | 2% (0.3%, 4%) | |||||
| Dispersion-modeled near-roadway NOx | –20% | –0.51 ppb | 2.05 ppb | Decrease by 8,400 (1,400, –14,300) | 3% (0.4%, 4%) | |||||
| NO2 | –20% | –3.9 ppb | 19.4 ppb | — | — | |||||
| O3 | –20% | –0.61 ppb | 38.7 ppb | — | — | |||||
| Scenario 3 (reduced regional pollution, increased near-roadway exposure) | ||||||||||
| Traffic proximity | 3.6% | 3.6% | 21.4% | Increase by 5,900 (1,000, 11,800) | 2% (0.3%, 4%) | |||||
| NO2 | –20% | –3.9 ppb | 19.4 ppb | — | — | |||||
| O3 | –20% | –0.61 ppb | 38.7 ppb | — | — | |||||
| aIncrease or decrease in asthma cases attributable to near-roadway pollution. | ||||||||||