Airborne pollen of Carya, Celtis, Cupressus, Fraxinus and Pinus in the metropolitan area of Monterrey Nuevo Leon, Mexico

Abstract

The concentration of pollen grains in the atmosphere over the metropolitan area of Monterrey, Nuevo Leon, Mexico, was analyzed throughout a year from March 2003-February 2004, focused on the genus Carya, Celtis, Cupressus, Fraxinus and Pinus owing to their interest as etiological pollinosis agents in diverse regions of the world. A 7-day Hirst type volumetric spore and pollen trap was located on a building roof of the city at 15 m from ground level for continuous sampling. The total quantity of pollen recorded for the study period was 21,083 grains/m(3), corresponding to 49.75 % of the taxa of interest. February and March were the months with higher pollen amounts in the air with 7,525 and 2,781 grains/m(3), respectively, and amounted to 49 % of total year through pollen. Fraxinus was the genus which contributed to the largest amount of pollen with 28 % of total grains (5,935 grains/m(3)) followed by Cupressus with 13 % (2,742 grains/ m(3)). Celtis, Pinus and Carya contributed with 5.3 % , 2.7 % , and 0.6 % of total pollen, respectively. These results indicate that Fraxinus and Cupressus are present in the area in sufficient quantity to indicate likely involvement in the origin of allergic disorders in the human population.

Full text

ORIGINAL ARTICLES AAEM
INTRODUCTION
Pollen grains are the masculine sex cells of fl owering
plants which are formed inside stamens and released into
the air once they are mature. Their biological function is to
reach the feminine part of a fl ower of the same species and
to make possible the fertilization of ovules [6]. The exist-
ence of pollen grains in the atmosphere is a natural phenom-
enon occurring as a result of the sex cycle of anemophilous
plants. The dispersion of such pollen grains is a dynamic
event governed by meteorological phenomena which infl u-
ence the mechanisms of emission, transport, permanence,
deposition and capture of the grains [36]. Carya, Celtis, Cu-
pressus, Fraxinus and Pinus are very abundant plants in the
metropolitan area of Monterrey, frequently used as ornate
plants in gardens and public parks, streets, avenues, side-
walks and private gardens [3, 28, 29]. Nevertheless, accord-
ing to diverse studies it has been recognized that the species
of these genus are etiological agents of pollinosis in diverse
places all over the world [14, 19, 22, 23, 26, 31, 35, 37].
Owing to the interest concerning the participation of pol-
len grains in seasonal allergic rhinitis episodes, the pollen
concentration in the air of the metropolitan area of Monter-
rey from the taxa above mentioned was studied in order
to obtain useful data for the prevention and diagnosis of
diseases caused by the inhalation of these pollen grains.
MATERIALS AND METHODS
Area of study. The metropolitan area of Monterrey is lo-
cated in the Mid-West part of the Nuevo Leon State, Mex-
ico, in the physiographic provinces of the Coastal Plain
AIRBORNE POLLEN OF CARYA, CELTIS, CUPRESSUS, FRAXINUS AND PINUS
IN THE METROPOLITAN AREA OF MONTERREY NUEVO LEON, MEXICO
Alejandra Rocha-Estrada, Marco Antonio Alvarado-Vázquez, Teresa Elizabeth Torres-Cepeda,
Rahim Foroughbakhch-Pournavab, Jorge Luis Hernández-Piñero
Departamento de Botánica, Facultad de Ciencias Biológicas, San Nicolás de los Garza, Nuevo León, México
Rocha-Estrada A, Alvarado-Vázquez MA, Torres-Cepeda TE, Foroughbakhch-Pour-
navab R, Hernández-Piñero JL: Airborne pollen of Carya, Celtis, Cupressus, Fraxinus
and Pinus in the metropolitan area of Monterrey Nuevo Leon, Mexico. Ann Agric Envi-
ron Med 2008, 15, 205–209.
Abstract: The concentration of pollen grains in the atmosphere over the metropolitan
area of Monterrey, Nuevo Leon, Mexico, was analyzed throughout a year from March
2003–February 2004, focused on the genus Carya, Celtis, Cupressus, Fraxinus and Pinus
owing to their interest as etiological pollinosis agents in diverse regions of the world.
A 7-day Hirst type volumetric spore and pollen trap was located on a building roof of
the city at 15 m from ground level for continuous sampling. The total quantity of pollen
recorded for the study period was 21,083 grains/m3, corresponding to 49.75% of the taxa
of interest. February and March were the months with higher pollen amounts in the air
with 7,525 and 2,781 grains/m3, respectively, and amounted to 49% of total year through
pollen. Fraxinus was the genus which contributed to the largest amount of pollen with
28% of total grains (5,935 grains/m3) followed by Cupressus with 13% (2,742 grains/
m3). Celtis, Pinus and Carya contributed with 5.3%, 2.7%, and 0.6% of total pollen,
respectively. These results indicate that Fraxinus and Cupressus are present in the area
in suffi cient quantity to indicate likely involvement in the origin of allergic disorders in
the human population.
Address for correspondence: Alejandra Rocha-Estrada, Departamento de Botánica,
Facultad de Ciencias Biológicas, Apartado Postal 38 F, Ciudad Universitaria, C.P. 66450,
San Nicolás de los Garza, Nuevo León, México. E-mail: arochaestrada@gmail.com
Key words: airborne, pollen, Carya, Celtis, Cupressus, Fraxinus, Pinus, Monterrey,
México.
Received: 11 September 2007
Accepted: 6 June 2008
Ann Agric Environ Med 2008, 15, 205–209

206 Rocha-Estrada A, Alvarado-Vázquez MA, Torres-Cepeda TE, Foroughbakhch-Pournavab R, Hernández-Piñero JL
of the North Gulf and the Sierra Madre Mountain range,
which includes the municipalities of Apodaca, Escobedo,
Guadalupe, Monterrey, Santa Catarina, San Nicolás de
los Garza, and San Pedro Garza García, which altogether
comprise an approximate area of 1,480 km2, located be-
tween the parallels 25°35´ and 25°50´ North latitude, and
between the meridians 99°59´ and 100°30´ West longitude,
to an altitude of 540 (between 400-800) m.a.s.l. [7].
The climate characteristic according to the classifi cation
system of Köeppen modifi ed by García [11], correspond to
dry warm and extreme steppe, with irregular rains at the
end of summer [-BS(h’)hw(é)] and an annual average tem-
perature of 22.1°C. Precipitation is scarce, between 300–
500 mm. The prevailing winds in the region come from
the Northeast and Southeast, which are more intense in the
warmer half of the year [21].
Trees, shrubs, herbs and palms are the main components
of the urban fl ora in the study area, which are cultivated in
the streets, avenues and parks of the city. The main spe-
cies present are Fraxinus spp., Ficus benjamina, Ligustrum
lucidum, Melia azederach, Platanus occidentalis, Quercus
spp., Pinus spp., Cupressus spp., Acacia farnesiana, A. rig-
idula, Phitecellobium dulce, Morus spp., Tamarindus indi-
cus, Punica granatum, Salix spp., Populus spp., Jacaranda
mimosifolia, Nerium oleander, Amaranthus spp., Washing-
tonia spp., Yucca spp., Ricinus communis [3, 29].
POLLEN SAMPLING AND COUNTS
The aerobiological sampling was made throughout a
year from March 2003–February 2004. Recommendations
from the Pan-American Aerobiology Association [30] for
sampling of anemophilous pollen were taken into account.
A Hirst type volumetric spore trap (Burkard Manufactur-
ing Co, Rickmansworth, Herts., UK) was located on the
roof of the main building of the Faculty of Biological Sci-
ences of the Universidad Autónoma de Nuevo Leon, about
15 m above ground level and elevated 1 m from the ceiling.
A Melinex tape of 345 mm covered with sticky silicone oil
was prepared and placed in the rotary drum of the equip-
ment. After the apparatus is turned on a constant air fl ow of
10 l/min penetrates through an orifi ce of 2 mm × 14 mm,
and the entering pollen grains stick to the tape, which is
moving at a speed of 2 mm/hr for a complete cycle of 7
days. The sampling tape was changed weekly and carefully
transported to the laboratory for processing and analysis.
The tape was divided in 7 segments, each one of 48 mm
in length, corresponding to each sampling day, and adhered
to standard glass slides covered with gelatin-glycerin and
stained with basic fuchsin. For taxa identifi cation the works
of Kremp [18], Erdtman [8, 9], Faegri and Iversen [10],
and Kapp et al. [17] were used. In addition, comparisons
of the obtained pollens samples were made with reference
Table 1. Month and total sum of the daily pollen values, expressed as grains/m3 of air.
Taxa Mar Apr May Jun Jul Agus Sep Oct Nov Dic Jan Feb Total
Carya 26 73 16 2 2 118
Celtis 91 34 59 536 140 116 63 17 1 14 48 1,118
Cupressus 99 30 1 163 59 504 1,627 259 2,742
Fraxinus 224 14 3 4 438 5,253 5,935
Pinus 72 256 172 5 1 1 8 5 7 51 577
Others 2,270 1,300 479 647 670 753 683 1,060 364 227 226 1,913 10,592
Total 2,781 1,706 729 1,192 811 870 746 1,243 432 736 2,311 7,525 21,083
0
2
4
6
8
10
12
14
2003-03-01
2003-04-01
2003-05-01
2003-06-01
2003-07-01
2003-08-01
2003-09-01
2003-10-01
2003-11-01
2003-12-01
2004-01-01
2004-02-01
Grains per cubic meter of air
0
5
10
15
20
25
30
35
40
45
50
2003-03-01
2003-04-01
2003-05-01
2003-06-01
2003-07-01
2003-08-01
2003-09-01
2003-10-01
2003-11-01
2003-12-01
2004-01-01
2004-02-01
Grains per cubic meter of air
Figure 1. Average daily concentrations of Carya pollen (grains/m3). Figure 2. Average daily concentrations of Celtis pollen (grains/m3).

Airborne pollen in Monterrey, México 207
specimens elaborated for this effect with grains of pollen
collected from the species belonging to the vegetation of the
study area. The total pollen concentration was determined
per day as well as the number of grains from each taxa per
air volume. In each glass slide, 4 longitudinal scans were
made under the optical microscope using a 400× objective
lens. The obtained results of the count per glass slide were
converted to values of density per air volume by multiply-
ing the values by a correction factor of 0.54 to obtain the
total number of grains per cubic meter of air.
RESULTS AND DISCUSSION
A total of 21,083 grains/m3 of air was registered in the pe-
riod from March 2003–February 2004 for the area of study,
of which 10,491 grains/m3 (49.75%) corresponds to pollen
from the taxa Carya, Celtis, Cupressus, Fraxinus and Pi-
nus; while the remaining 10,592 grains/m3 corresponded
to other trees, shrubs and weeds. The months of maximum
pollen concentration were March 2003 (2,781 grains/m3)
and February 2004 (7,525 grains/m3) when 48.88% of the
total pollen was obtained (Tab. 1).
The Carya species reported in the study area correspond
to C. cordiformis (Wangenh.) K. Koch and C. illionensis
(Wangenh.) K. Koch [2]. The pollen concentration of Carya
was 118 grains/m3 of air, representing 0.56% of total pol-
len. Pollen from this taxon was present during the months
of March–May, October and February, reaching maximum
values in the month of April with 73 grains/m3, with a maxi-
mum daily average concentration of 9 grains/m3 registered
on 10 April (Fig. 1). These results are similar to those ob-
tained in Israel where there is a well defi ned pollen sea-
son from mid April–May [27]. On the other hand, in North
America pollen from this species is considered as an impor-
tant cause of allergic rhinitis. It has been also reported that
in Israel it constitutes a possible etiological agent for the
development of the asthma in children [24, 27, 33].
The Celtis species most abundant in the metropolitan
area of Monterrey are C. laevigata Willd. and C. pallida
Torr. [2, 29]. The registry of total pollen for Celtis spp. was
1,118 grains/m3 of air (5.30%). These grains were present
throughout the whole period of study except during the
month of December, reaching its maximum monthly con-
centration in June with 536 grains/m3, and a mean maxi-
mum day concentration on 20 June with 45 grains/m3 of
air (Fig. 2). Celtis genus anemophily has been reported in
Italy, United States and Argentine [12, 20, 24, 32, 34].
The registered species for the genus Cupressus in the
study area were C. arizonica Greene (white cedar) and C.
sempervirens L. (column cypress) [2, 29]. The pollen con-
centration of Cupressus spp. was 2,742 grains/m3 of air,
representing 13% of the total pollen. This taxon reached its
maximum monthly concentration in January (1,627 grains/
m3) with a maximum daily average of 267 grains/m3 4 Jan-
uary (Fig. 3). Similar results were registered in Santiago de
Compostela (Spain), where the maximum levels of this pol-
len were recorded from December–April, reaching peaks
between January–March [1], whereas to the southwest of
Sydney (Australia) counts superior to 1,000 grains/m3 of
air were reported, with a maximum daily average of 1,842
grains/m3 during the second week of October [5].
0
50
100
150
200
250
300
2003-03-01
2003-04-01
2003-05-01
2003-06-01
2003-07-01
2003-08-01
2003-09-01
2003-10-01
2003-11-01
2003-12-01
2004-01-01
2004-02-01
Grains per cubic meter of air
0
50
100
150
200
250
300
350
400
2003-03-01
2003-04-01
2003-05-01
2003-06-01
2003-07-01
2003-08-01
2003-09-01
2003-10-01
2003-11-01
2003-12-01
2004-01-01
2004-02-01
Grains per cubic meter of air
0
5
10
15
20
25
30
2003-03-01
2003-04-01
2003-05-01
2003-06-01
2003-07-01
2003-08-01
2003-09-01
2003-10-01
2003-11-01
2003-12-01
2004-01-01
2004-02-01
Grains per cubic meter of air
Figure 3. Average daily concentrations of Cupressus pollen (grains/m3).
Figure 5. Average daily concentrations of Pinus pollen (grains/m3).
Figure 4. Average daily concentrations of Fraxinus pollen (grains/m3).

208 Rocha-Estrada A, Alvarado-Vázquez MA, Torres-Cepeda TE, Foroughbakhch-Pournavab R, Hernández-Piñero JL
The species of the genus Fraxinus occurring in the met-
ropolitan area of Monterrey were F. americana L., F. ber-
landieriana A.DC., F. cuspidata Torr., F. greggii A. Gray y
F. uhdei (Wenz.) Lingel [2]. The sum of the concentrations
of pollen from Fraxinus spp. during the period of study
was 5,935 grains/m3 of air (28.15%), with February be-
ing the month with the greatest concentration of 5,253.12
grains/m3, not registering pollen presence in the months
from July–December. The average daily maximum con-
centration was of 343 grains/m3 of air on 19 February (Fig.
4). Horak et al. [1980, cited by Peeters, 25] consider that
for this taxon the daily average of 167 grains/m3 of air are
a critical concentration concerning the appearance of al-
lergic symptoms in humans. On the other hand, Weryszko-
Chmielewska and Piotrowska [37] registered main peri-
ods of pollination lasting between 17–28 days (2001 and
2002), and with maximum daily concentrations of 143 and
287 grains/m3 of air in Lublin (Poland), whereas concen-
tration peaks between 23–837 grains/m3 were counted in
Vienna (Austria) [14]. Anemophily of the Fraxinus genus
has been observed in France, Hungary, Argentine, Spain,
Switzerland and Austria [12, 14, 15, 19, 23, 25].
The Pinus species reported in the study area are P. cem-
broides Zucc, P. greggii Engelm., P. halepensis Mill., P.
heldarica Medw and P. pseudotrobus Lindl. [2, 29]. The
total concentration of Pinus spp. pollen during the period
of study was 577 grains/m3 of air, representing approxi-
mately 2.73% of the total of pollen registered. The monthly
maximum concentrations were recorded during April (256
grains/m3) and May (172 grains/m3), with the maximum
daily average concentration reached on 8 May with 28
grains/m3 of air (Fig. 5). This daily average concentration
is relatively low in comparison with the registered values
for Ciudad de la Plata (Argentine), Vigo (Spain) and Bris-
bane (Australia) where daily average concentrations of
2,028, 1,105 and 158 grains/m3 of air have been registered
respectively [13, 16, 23]. On the other hand, Levetin et al.
[20] have reported an annual total concentration for Pinus
pollen of 1,246 grains/m3 of air in Tulsa (United States),
whereas for Bilbao (Spain) a total concentration of 6,118
grains/m3 of air was registered [4], which are values notice-
ably higher to those found in the present study. Although
the allergenic effects of pollen from the Pinus genus have
been documented in diverse studies, high controversy still
remains about the accuracy of this statement [1, 4, 22].
CONCLUSIONS
The total amount of pollen registered for the metropolitan
area of Monterrey was 21,083 grains/m3, of which 10,491
grains/m3 (49.75%) correspond to Carya, Celtis, Cupres-
sus, Fraxinus and Pinus. The months of maximum pollen
concentration were March and February when 48.88%
of the total pollen grains were obtained. Pollen from Cu-
pressus and Fraxinus reached the highest total concentra-
tions during the period of study, whereas Carya and Pinus
presented the lowest total concentration. Fraxinus and
Cupressus were the taxa with the highest maximum daily
concentrations with 343 and 267 grains/m3, respectively.
The pollen concentration values registered for Fraxinus
and Cupressus in the metropolitan area of Monterrey dur-
ing the period of study showed a high probability of be-
ing causative agents of allergic disorders in the population,
whereas the three remaining taxa showed concentrations
in amounts with a smaller probability of causing these dis-
orders. However, studies with longer periods of sampling
time are recommended to evaluate the aerobiological be-
haviour of these taxa in order to have more precise and
reliable data.
Acknowledgements
The authors thank PAICyT-UANL (Project CN917-04) and
PROMEP (PROMEP/103.5/04/1371 and PROMEP/103.5/05/2230)
for their economic support.
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