Trends in prevalence of allergic rhinitis and correlation with pollen counts in Switzerland

Abstract

In recent decades, a large number of epidemiological studies investigating the change of prevalence of hay fever showed an increase in the occurrence of this disease. However, other studies carried out in the 1990s yielded contradictory results. Many environmental factors have been hypothesized to contribute to the increasing hay fever rate, including both indoor and ambient air pollution, reduced exposure to microbial stimulation and changes in diets. However, the observed increase has not convincingly been explained by any of these factors and there is limited evidence of changes in exposure to these risk factors over time. Additionally, recent studies show that no further increase in asthma, hay fever and atopic sensitisation in adolescents and adults has been observed during the 1990s and the beginning of the new century. As the pattern of pollen counts has changed over the years, partly due to the global warming but also as a consequence of a change in the use of land, the changing prevalence of hay fever might partly be driven by this different pollen exposure. Epidemiological data for hay fever in Switzerland are available from 1926 until 2000 (with large gaps between 1926 and 1958 and 1958 to 1986) whereas pollen data are available from 1969 until the present. This allows an investigation as to whether these data are correlated provided the same time spans are compared. It would also be feasible to correlate the pollen data with meteorological data which, however, is not the subject of our investigation. Our study focuses on analyzing time series of pollen counts and of pollen season lengths in order to identify their trends, and to ascertain whether there is a relationship between these trends and the changes in the hay fever prevalence. It is shown in this paper that the pollen exposure has been decreasing in Basel since the beginning of the 1990s whereas the rate of the hay fever prevalence in Switzerland remained approximately unchanged in this period but with a slight tendency to decrease. In Locarno, most of the pollen species also show a decreasing trend, while in Zurich, the development is somewhat different as the pollen counts of most of the pollen types have been increasing. It is interesting, however, that some of the pollen counts of this station (grass, stinging nettle, mugwort and ragweed) have been decreasing in the period 1982--2007.

Pollen Season Trends (1973-2013) in Stockholm Area, Sweden

“…The prevalence of pollen allergy is increasing in many countries of Europe, [18,26]. In Switzerland for example the prevalence of hay fever increased from 4.8% in 1958 to 16.1% in 1999 [27]. A Danish study reported an increase in pollen allergy from 6.5% in 1987 to 10.3% in 1997 [28], whereas another study from the same country showed an increase in pollen allergy prevalence of about 50% between 1989 and 1997 [29].…”

“…In 2009, approximately 30% of the Stockholm population reported to be allergic to pollen, and the self-reported prevalence of hay fever increased from 15% in 1997 to 23% in 2007 in the same region [30]. Several hypotheses, including the hygiene hypothesis and the possible role of air pollution and land use change have been discussed as the underlying reasons [27,31,32], but so far there is no definite explanation to this development and the role of changing pollen seasonality is so far unexplored.…”

Enhancing effects of trichloroethylene and tetrachloroethylene on type I allergic responses in mice

“…In recent years, many epidemiological studies have shown that the incidences of allergic diseases such as asthma and pollinosis are increasing (Beasley et al, 2003;Frei and Gassner, 2008). Allergic diseases are caused by both genetic and environmental factors (Burney et al, 1990;Peat and Li, 1999).…”

Aerobiology in the International Journal of Biometeorology, 1957–2017

“…Other research on the impacts of climate change on pollen season characteristics has subsequently been published in IJB, including Galán et al (2005), Frei and Gassner (2008), Newnham et al (2013) and Sofia et al (2017), to name but a few. As noteworthy as the IJB contribution to this area of research has been, it has not been the sole domain of such work.…”