Clark County Aeroallergen History and Cycles

In November, 2010, as a result of the economic downturn and declining budgets, as well as the retirement of a long-term key aeroallergen monitoring technician, the Board of County Commissioners authorized the termination of the pollen monitoring program as a necessary cost-saving measure.  Although the program will undoubtedly be missed by some of our residents and medical professionals, the pollen monitoring program is not a required or mandated air quality program.  We have learned much about the seasonal aeroallergen patterns that occur in the Las Vegas Valley and surrounding areas in the past 25 years.  The following timeline and seasonal sampling information will be helpful to those desiring general information about the prevalent pollen patterns typically found in the area.  Recently the American Academy of Allergy Asthma Immunology (AAAAI), together with the University of  Nevada, Las Vegas (UNLV) have started posting this information here.

The concerns for aeroallergens are rooted in the high non-native mulberry and olive pollen levels that occur every spring.  In 1985, Clark County Air Quality (then known as the Air Pollution Control Division of the Clark County Health District) began sampling for aeroallergens.  These samples were collected at three monitoring sites, Griffith Elementary, Channel 10, and Burkholder Middle School.  With the increased interest in the pollen levels, the network was increased to six sites in 1988.  The new sites included Boulder City Library, a desert site located on the outskirts of Boulder City, and Squires Elementary in North Las Vegas.

In 1991, the Air Pollution Control Hearing Board enacted section 44 of the Air Pollution Control regulations, which prohibited any further planting of the fruitless mulberry and the European olive.  Provisions in the regulation made exceptions for low pollinating varieties of the European olive.  A study was conducted by the University of Nevada, Las Vegas to compare the pollen output of two low pollinating varieties to the traditional European olive.  The two hybrids tested were the Swan Hill and the Wilson.  As a result of this study, three nurseries sought and were given exemptions to sell these hybrids in Las Vegas.  In 1993 two more pollen monitoring sites were added to the sampling network at McMillan Elementary and Diskin Elementary.

As a result of consistently high olive pollen at the Boulder City Library site, an agreement was reached to remove the European olive trees surrounding the site, and replace them with a low pollinating hybrid.  In 1997 another site, Boulder City Hall, was added to compare the olive levels to the levels analyzed at the Boulder City Library.  In that year two other pollen monitoring sites were added --Winterwood and Baskin Park.  In 2001, it was determined that two sites in Boulder City were no longer needed and the Boulder City Library site was discontinued.

In an effort to combine pollen monitoring sites and air pollutant monitoring sites, several pollen monitoring sites were relocated in 2004.  Channel 10 was relocated to Orr Middle School; Burkholder was moved to the Southeast Valley site; Desert was moved to Apex; Squires was moved to J.D. Smith; McMillan was moved to Lone Mt.; and Baskin was moved to Paul Meyer.  Two pollen monitoring network changes occurred in 2007.  Apex was discontinued as historical data showed the effects of wind and pollen release in remote areas.  Further sampling was unnecessary.  Baskin Park was also shut down that year.  Due to a large population of mulberry and olive trees in the park, it was determined that it was effectively performing source sampling and wasn’t indicative of a typical neighborhood.  That same year, the sampler at Southeast Valley was relocated to the Green Valley monitoring site.  That relocation was performed to collect data that supported a larger population base.

Pollen levels vary each year based on rainfall and dates sampled.  As sampling was done two days per week during the peak pollen season, it is possible to miss the actual peak pollen release.  The highest mulberry level of almost 70,000 grains per cubic meter was recorded in 2005.  Since then the peak levels have been significantly less.  Following is a table showing the mulberry and olive levels for each sampling site since 1988.

 

 Monitoring Site  Year Peak
Mulberry 
Peak
Olive 
 Griffith Elementary School (1985 to 2010)

1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010

605
729
505
2009
5364
10632
12667
17306
37441
59681
44855
14673
26000
34533
40672
46366
25214
69224
13135
30337
15873
26101
50

50
160
55
29
908
222
530
514
244
253
234
288
278
399
214
135
275
211
124
237
277
86
107

 Channel 10 (1985 to 2003) 1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003

65
455
202
432
854
4990
5783
2939
7668
7604
9874
3265
6416
10432
2142
2812

50
183
121
59
265
237
430
438
795
697
348
779
424
336
96
153
 Orr (2004 to 2010) 2004
2005
2006
2007
2008
2009
2010
7423
8284
4199
267
6716
14425
18
828
1014
326
856
928
341 
1199
 Burkholder Middle School (1985 to 2003) 1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
50
523
125
119
352
1021
3100
1408
3470
5040
7002
1065
4016
4853
1889
1132

40
77
86
35
76
210
250
159
98
44
126
244
22
28
7
17

 Henderson (2004 to 2006)

2004
2005
2006 

1764
1792
691
102
61
20
Green Valley (2007 to 2010)  2007
2008
2009 
2010
5495
328
696
5

94
30
81
48

 Boulder City Library (1988 to 2001) 1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
65
564
150
462
1463
6426
3207
5716
12043
12851
35706
1065
11519
12129
50
215
74
35
590
1134
1588
1820
3924
95
168
47
38
85
 Desert (1988 to 2003)

1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003

10
42
51
17
32
199
667
213
524
649
973
386
934
595
313
216

50
44
18
12
16
12
48
89
44
50
25
19
15
34
17
38
 Apex (2004 to 2007) 2004
2005
2006
2007
124
51
79
237
17
17
22
12
Squires Elementary School (1988 to 2003)  1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
430
975
268
1432
6339
10962
14062
14145
25457
28238
35370
14616
30238
43181
9401
10031
20
376
66
47
84
121
254
755
269
355
323
215
348
260
153
492
 J.D. Smith (2004 to 2010) 2004
2005
2006
2007
2008
2009
2010
21006
11696
5676
21256
9539
14578 
11

158
640
188
341
122
130
264

Diskin Elementary School (1993 to 2003)  1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
681
2032
2749
11897
9063
21758
8508
6137
10153
5023
3144
31
103
707
171
326
85
183
69
304
201
242
Paul Meyer (2004 to 2010) 2004
2005
2006
2007
2008
2009
2010
1341
14764
7535
2328
1614
7555
20
91
71
632
79
364
206
176
McMillan Elementary School (1993 to 2003) 1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
1236
8656
1826
7959
3280
4685
2986
6416
3404
1208
1188
530
106
70
145
272
101
76
148
84
40
20
Lone Mountain (2004 to 2010) 2004
2005
2006
2007
2008
2009
2010
3146
1323
326
3626
1907
2935
7
160
30
38
147
56
43
21
Boulder City Hall (1997 to 2010)  1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
16319
30219
7420
11380
27551
9952
6102
22218
9261
4526
37778
5342
20453
140
164
63
250
19
278
173
56
175
43
196
40
114
30
13
Winterwood (1997 to 2010) 1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
18474
24548
5915
15678
22148
11793
5880
28208
15437
11964
15608
12821
22437
16
190
269
909
275
785
79
242
242
510
239
280
124
234
182
Baskin Park (1997 to 2007) 1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
38933
64160
22037
34648
59884
40672
8723
38346
59063
16108
33239
1686
678
1987
1857
4910
848
1382
1063
1524
2838
1272

Last modified at 11/2/2015 14:51 by Bradley Mach