LASSEN COUNTY AIR POLLUTION CONTROL DISTRICT
RULE 6:9  AIR QUALITY IMPACT ANALYSIS
The following table is provided as a screening method to estimate the worst case air quality impact of carbon monoxide,
particulate matter, oxides of sulfur and oxides of nitrogen of a proposed point source without the use of sophisticated
modeling techniques. For oxidant, or where another source with unknown impact is being constructed in the affected
area, or if the values obtained from this method approach the ambient air quality standards or increments established
pursuant to this rule, modeling may be required at the discretion of the APCO to determine more precisely if a
violation could occur. In such instances the models, data bases, and other requirements specified in EPA's Guidelines
on Air Quality models (OAQPS 1.2080) must be used. The use of alternative models requires concurrence of the executive
office of the ARB and the regional administrator of EPA.
The effective stack height should be calculated for use with the impact table. The effective stack height is the height of the proposed stack plus the expected plume rise. Since the plume rise may vary under different operating conditions, the table should be used with several projected effective stack heights to determine which would represent worst case conditions. If the proposed stack height is higher than is dictated by good engineering practices, the effective stack height for use with the impact table should be calculated as if the stack had been designed according to good engineering practices.
Using the impact table, determine the estimated downwind concentrations by reading the value which corresponds to the effective stack height and source strength of the proposed source. The table also provides the estimated distance from the source to the point of maximum ground level impact. If the precise effective stack height for the proposed source is not listed, interpolation can be used to determine the approximate downwind concentration.
Example  To determine the downwind concentrations attributable to a proposed source with an effective stack height of 45 meters and a source strength of 137 lb/hr;
= 1478 ug/m3 (this estimated maximum onehour concentration for the proposed 137 lb/hr source is to be added to ambient concentration levels).
x ug/m^{3} = (1520  1300)
x (137  120) + 1300
140  120
Values for maximum concentrations for 3 hour, 8 hour, and 24 hour may be obtained by multiplying the 1 hour concentrations by following factors: 3 hour = O.9; 8 hr = 0.8; 24 hr = 0.4.WORST CASE ESTIMATES OF POINT SOURCE AIR QUALITY IMPACTS
Stack Height (m) 
Downwind Distances to Maximum Estimated Concentration 


. 
. 
5 lb/hr 
10 lb/hr 
20 lb/hr 
40 lb/hr 
80 lb/hr 
120 lb/hr 

5 
<100 
3150 
6300 
12800 
25200 
50400 
75700 

10 
100 
945 
1890 
3840 
7560 
15120 
22700 

15 
150 
380 
760 
1530 
3020 
6040 
9080 

20 
200 
220 
440 
900 
1760 
3530 
5300 

30 
300 
90 
190 
380 
760 
1510 
2270 

40 
200 to 400 
50 
110 
220 
430 
870 
1300 

50 
250 to 450 
40 
70 
150 
290 
580 
880 

70 
350 
20 
40 
80 
170 