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Seasonal Rhinitis and Environmental Factors in Madrid
J Investig Allergol Clin Immunol 2019; Vol. 29(5): 371-377
© 2019 Esmon Publicidad
doi: 10.18176/jiaci.0368
Introduction
As many as 44 types of pollen coexist in Madrid, Spain,
although seasonal allergic rhinitis is produced mainly by
4 specific types: Cupressaceae (January and February),
Platanaceae (March and April), Poaceae, and Oleaceae (May
and June) [1].
Grass pollen is the most allergenic in the area, and up to
88% of patients are polysensitized [2]. Thus, most allergy
patients in the center of Spain are sensitized to 4 or 5 different
types of pollen, thus implying a longer duration of symptoms
throughout the year and greater difficulty when applying
pharmacological or prophylactic treatment. In theAlergológica
2015 study, the prevalence of rhinitis (all causes) increased
from 55.5% to 62.0% (
P
<.001) compared with the previous
study (2005), and grass pollen grains were the principal
allergen implicated, with prevalence increasing from 34.8% to
73.7%. In Madrid, this increase was from 61.9% to 87.1% [3].
The age range most affected by seasonal allergic rhinitis is
25-34 years. Consequently, the disease mainly affects young
adults, although the overall range is very wide, affecting
patients of practically any age [3].
Climate change is increasing the length and intensity of
the pollen season, with a significant impact on the millions of
patients who already have allergies [4]. Increasing temperatures
lead to earlier and longer pollen and allergy seasons, with more
frost-free days and earlier and longer flowering seasons [5,6].
Higher temperatures also increase ozone production, which
sensitizes the respiratory tract to allergens [7]. Higher carbon
dioxide levels cause greater plant growth, resulting in increased
pollen production and increased pollen potency [8]. More
fall-winter precipitation further contributes to increased pollen
production [9].
The aim of this study was to assess the relationships
between meteorological and pollution-related variables and
the symptoms of patients with seasonal allergic rhinitis due
to sensitization to grass pollen during 2 different time periods
in Madrid.
Material and Methods
During the periods March 23 to December 31, 1996 and
March 23 to December 31, 2009, we carried out the following
studies:
– Daily grass pollen count using a Burkard collector
(Clínica Subiza, Madrid), as previously described [1].
The main pollen season ran from the first date
with 10 grains/m
3
on 3 consecutive days until the date
of the last 3 consecutive records at the same level.
– Daily measurement of meteorological data (temperature,
rain, humidity, wind speed) using data from Barajas-
Madrid station (National Meteorological Agency).
– Daily measurement of pollution (ozone, CO, SO
2
, NO
2
,
PM10) from the Escuelas Aguirre station (Madrid City
Council).
372
Table.
Descriptive Statistics of the Main Variables Analyzed During Both Study Periods: 23 March to 31 December in 1996 and 2009
Variables
a
No. valid Missing Mean (SD) Median
No. valid Missing Mean (SD) Median
(Minimum- Maximum)
(Minimum-Maximum)
Symptom score
284
81
1.45 (1.74)
284
81
2.33 (1.34)
1.00 (0.00-8.00)
1.74 (0.61-6.61)
Grass pollen counts, grains/m
3
284
81
21.8 (57.2)
284
81
8.28 (17.9)
2.00 (0.00-552.0)
1.00 (0.00-121.0)
SO
2
, µg/m
3
284
81
17.7 (9.25)
284
81
9.87 (3.42)
15.0 (6.00-61.0)
9.00 (6.00-21.0)
CO, µg/m
3
284
81
13.7 (6.71)
284
81
0.40 (0.13)
12.0 (5.00-40.0)
0.37 (0.19-1.02)
NO
2
, µg/m
3
284
81
64.2 (17.0)
282
83
52.6 (14.0)
61.5 (32.0-117.0)
51.0 (17.0-96.0)
PM10, µ/m
3
284
81
35.2 (8.75)
128
237
30.0 (10.7)
34.0 (19.0-61.0)
29.0 (10.0-60.0)
O
3
, µg/m
3
284
81
33.7 (15.1)
284
81
43.6 (17.9)
34.0 (3.00-71.0)
45.0 (8.00-82.0)
Temperature, ºC
284
81
18.1 (6.64)
284
81
18.0 (7.31)
17.8 (2.50-31.7)
18.1 (0.00-29.8)
Humidity, %
284
81
59.0 (13.6)
284
81
34.1 (19.8)
55.0 (37.0-95.0)
29.0 (8.00-95.0)
Wind speed, m/s
284
81
16.8 (6.06)
284
81
14.8 (8.70)
16.0 (7.00-39.0)
13.0 (0.00-51.0)
Rainfall, L/m
2
284
81
0.87 (2.99)
284
81
8.17 (26.7)
0.00 (0.00-24.0)
0.00 (0.00-209.0)
a
Significant differences (
P
=.000, nonparametric paired samples Wilcoxon test) were found for all variables except temperature.