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 |
605 |
50 |
| Channel 10 (1985 to 2003) | 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 |
65 |
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 |
| Henderson (2004 to 2006) | 2004 |
1764 1792 691 |
102 61 20 |
| Green Valley (2007 to 2010) | 2007 2008 2009 2010 |
5495 328 696 5 |
94 |
| 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 |
10 |
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 |
| 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 |