Seasonal Rhinitis and Environmental Factors in Madrid
J Investig Allergol Clin Immunol 2019; Vol. 29(5): 371-377
© 2019 Esmon Publicidad
Ozone levels are mostly higher in rural areas than in
cities. Ozone is degraded by NO, which is also involved in its
formation. This degradation occurs more often in cities than
in rural areas, because there is more NOx in cities. For this
reason, ozone concentrations are higher in rural areas than in
According to the review of evidence on health aspects of
air pollution in the REVIHAAP Project (Technical Report)
(2013) , the European threshold of 180 µg/m
the population may thus not be viewed as an effective threshold
value under which absolutely no one will experience any effect at
all. However, theWorld Health Organization (WHO) postulated
that the effects of concentrations lower than 200 µg/m
limited in severity and will only prevail in less than 5% of
the total population . Warning the whole population at
lower concentration levels is therefore not advised.As such, the
threshold values can be considered a sliding scale, and—albeit
somewhat artificially—it is possible to talk about amild response
at (hourly mean) concentrations of 180-240 µg/m
, a moderate
response at 240-360 µg/m
, and a severe response above
[28,29]. The review concludes that a considerable
amount of new scientific information on the adverse health
effects of particulate matter, ozone, and NO
observed at levels
commonly present in Europe in recent years . This new
evidence supports the scientific conclusions of the WHO air
quality guidelines, last updated in 2005, and indicates that, in
some cases, the effects occur at air pollution concentrations
lower than those serving to establish these guidelines .
Pollution particles also contain diesel exhaust particles.
At present, 70% of all particles and 90% of those <5 µm
(respirable particles) are produced from its combustion, which
induces important biological changes, such as a more marked
2 response [30,31].
The rising frequency of obstructive respiratory diseases
during recent years, in particular allergic asthma, can be
partially explained by changes in the environment, with the
increasing presence in the atmosphere of chemical triggers
(particulate matter and gaseous components such as NO
ozone) and biologic triggers (aeroallergens). Consequently,
measures need to be taken to mitigate the future impact of
climate change and global warming . Over the last 50 years,
the earth’s temperature has risen markedly, likely because of
growing concentrations of anthropogenic greenhouse gas .
For this reason, it is important to emphasize to patients that
climate change is increasing exposure to allergens and suggest
what they can do to minimize their exposures and thus reduce
allergy and asthma symptoms, such as checking pollen levels
frequently. In Spain, patients can sign up for free alerts from
the Spanish Society of Allergy and Clinical Immunology
Aerobiology Network. For patients with asthma, it is important
to check ozone levels.
The effect of temperature and pollution (mainly ozone,
even at lower atmospheric concentrations than those
established in guidelines about its effects on health) could
contribute to the higher seasonal allergic rhinitis symptom
score observed in 2009.
We highlight the need to continue research into the impact
of these changes and into strategies and policies to reduce
greenhouse gas emissions and air pollution.
The authors declare that no funding was received for the
Conflicts of Interest
The authors declare that they have no conflicts of interest.
This study was presented at Simposio Internacional de
Aerobiología, Contaminación y Cambio Climático, 26-28
October 2017, Murcia, Spain.
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