Outdoor environments and human pathogens in air

Are pathogens in outdoor air a health issue at present or will they become a problem in the future? A working group called AirPath - Outdoor Environments and Human Pathogens in Air was set up in 2007 at University College London, UK with the aim of opening new discussion and creating a research network to investigate the science and impacts of outdoor pathogens. Our objective in this paper is to review and discuss the following areas: What is the source of human pathogens in outdoor air? What current, developing and future techniques do we need? Can we identify at-risk groups in relation to their activities and environments? How do we prepare for the anticipated challenges of environmental change and new and emerging diseases? And how can we control for and prevent pathogens in outdoor environments? We think that this work can benefit the wider research community and policy makers by providing a concise overview of various research aspects and considerations which may be important to their work

Allergies respiratoires, pollens et polluants

National audienceFor 30 years, an increased incidence of respiratory allergy and asthma has been observed, particularly in children and young people living in urban areas of developed countries. A genetic origin is unlikely due to the rapidity of this increase and environmental factors (diet, lifestyle, exposure to xenobiotics...) should be involved. Epidemiological studies have shown that atmospheric pollutants may play a role. They could have an effect on the respiratory tract by inducing irritation, inflammation, airway hyperresponsiveness or enhancing respiratory allergies (adjuvant effect) or they could have an effect on the aeroallergens, in particular the pollens. Experimental studies have shown that pollen exposure to pollutants induce enhanced deformation or fracture of the external envelope linking to an enhanced liberation of intracytoplasmic allergenic granules and induce also a qualitative and quantitative modification of allergens. However, few experimental studies have shown that pollutant-exposed pollens are more allergenic that "clean" pollens. One important point to consider is the enhanced granule liberation by exposed pollens. Due to the small size of the granules, the allergen bioavailability may increase, leading to higher incidence of respiratory allergies.Depuis 30 ans, une incidence accrue des allergies respiratoires est observée, notamment chez les enfants et les adolescents vivant dans les zones urbaines des pays industrialisés. Il est admis que cette augmentation est trop rapide pour être liée à des facteurs génétiques et que d'autres facteurs, notamment environnementaux (alimentation, mode de vie, contact avec des xénobiotiques...) sont impliqués. Les études épidémiologiques montrent que les polluants de l'air en particulier semblent jouer un rôle important dans l'incidence des allergies. Ils peuvent agir soit par action au niveau du système respiratoire, en provoquant une irritation, une inflammation, une augmentation de l'hyperréactivité bronchique non spécifique ou en potentialisant une réponse allergique pré-existante (effet adjuvant), soit par action au niveau des aéroallergènes, dont les pollens représentent la majeure partie. Les principaux effets observés expérimentalement sont une augmentation des déformations et fractures de l'enveloppe externe conduisant à une libération accrue de granules intracytoplasmiques, eux-mêmes allergisants et une modification quantitative et qualitative des allergènes. Peu de travaux ont toutefois clairement mis en évidence une augmentation du potentiel allergisant des pollens après exposition aux polluants. Une piste à explorer reste la libération plus importante des granules intrapolliniques qui, de part leur petite taille, pourraient augmenter la biodisponibilité des allergènes et donc la fréquence et la gravité des allergies respiratoires

Mapping the Birch and Grass Pollen Seasons in the UK Using Satellite Sensor Time-series

Grass and birch pollen are two major causes of seasonal allergic rhinitis (hay fever) in the UK and parts of Europe affecting around 15-20% of the population. Current prediction of these allergens in the UK is based on (i) measurements of pollen concentrations at a limited number of monitoring stations across the country and (ii) general information about the phenological status of the vegetation. Thus, the current prediction methodology provides information at a coarse spatial resolution only. Most station-based approaches take into account only local observations of flowering, while only a small number of approaches take into account remote observations of land surface phenology. The systematic gathering of detailed information about vegetation status nationwide would therefore be of great potential utility. In particular, there exists an opportunity to use remote sensing to estimate phenological variables that are related to the flowering phenophase and, thus, pollen release. In turn, these estimates can be used to predict pollen release at a fine spatial resolution. In this study, time-series of MERIS Terrestrial Chlorophyll Index (MTCI) data were used to predict two key phenological variables: the start of season and peak of season. A technique was then developed to estimate the flowering phenophase of birch and grass from the MTCI time-series. For birch, the timing of flowering was defined as the time after the start of the growing season when the MTCI value reached 25% of the maximum. Similarly, for grass this was defined as the time when the MTCI value reached 75% of the maximum. The predicted pollen release dates were validated with data from nine pollen monitoring stations in the UK. For both birch and grass, we obtained large positive correlations between the MTCI-derived start of pollen season and the start of the pollen season defined using station data, with a slightly larger correlation observed for birch than for grass. The technique was applied to produce detailed maps for the flowering of birch and grass across the UK for each of the years from 2003 to 2010. The results demonstrate that the remote sensing-based maps of onset flowering of birch and grass for the UK together with the pollen forecast from the Meteorology Office and National Pollen and Aerobiology Research Unit (NPARU) can potentially provide more accurate information to pollen allergy sufferers in the UK

Ragweed as an Example of Worldwide Allergen Expansion

<p/> <p>Multiple factors are contributing to the expansion of ragweed on a worldwide scale. This review seeks to examine factors that may contribute to allergen expansion with reference to ragweed as a well-studied example. It is our hope that increased surveillance for new pollens in areas not previously affected and awareness of the influence the changing environment plays in allergic disease will lead to better outcomes in susceptible patients.</p

Pollen as atmospheric cloud condensation nuclei

Anemophilous (wind‐dispersed) pollen grains are emitted in large quantities by vegetation in the midlatitudes for reproduction. Pollen grains are coarse particles (5–150 µm) that can rupture when wet to form submicron subpollen particles (SPP) that may have a climatic role. Laboratory CCN experiments of six fresh pollen samples show that SPP activate as CCN at a range of sizes, requiring supersaturations from 0.81 (± 0.07)% for 50 nm particles, 0.26 (± 0.03)% for 100 nm particles, and 0.12 (± 0.00)% for 200 nm particles. Compositional analyses indicate that SPP contain carbohydrates and proteins. The SPP contribution to global CCN is uncertain but could be important depending on pollen concentrations outside the surface layer and the number of SPP generated from a single pollen grain. The production of hygroscopic SPP from pollen represents a novel, biologically driven cloud formation pathway that may influence cloud optical properties and lifetimes, thereby influencing climate.Key PointsPollen grains can rupture when wet to form submicron subpollen particles (SPP)Laboratory experiments show that SPP are hygroscopic and can act as CCNPollen grains may contribute to CCN in northern midlatitudesPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111953/1/grl52890.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/111953/2/grl52890-sup-0001-Supplementary.pd

Adaptation to Impacts of Climate Change on Aeroallergens and Allergic Respiratory Diseases

Climate change has the potential to have many significant impacts on aeroallergens such as pollen and mould spores, and therefore related diseases such as asthma and allergic rhinitis. This paper critically reviews this topic, with a focus on the potential adaptation measures that have been identified to date. These are aeroallergen monitoring; aeroallergen forecasting; allergenic plant management; planting practices and policies; urban/settlement planning; building design and heating, ventilating, and air-conditioning (HVAC); access to health care and medications; education; and research

Impact of meteorological variation on hospital visits of patients with tree pollen allergy

<p>Abstract</p> <p>Background</p> <p>Climate change could affect allergic diseases, especially due to pollen. However, there has been no epidemiologic study to demonstrate the relationship between meteorological factors, pollen, and allergic patients. We aimed to investigate the association between meteorological variations and hospital visits of patients with tree pollen allergy.</p> <p>Methods</p> <p>The study subjects were adult patients who received skin prick tests between April and July from 1999 to 2008. We reviewed the medical records for the test results of 4,715 patients. Patients with tree pollen allergy were defined as those sensitized to more than 1 of 12 tree pollen allergens. We used monthly means of airborne tree pollen counts and meteorological factors: maximum/average/minimum temperature, relative humidity, and precipitation. We analyzed the correlations between meteorological variations, tree pollen counts, and the patient numbers. Multivariable logistic regression analyses were used to investigate the associations between meteorological factors and hospital visits of patients.</p> <p>Results</p> <p>The minimum temperature in March was significantly and positively correlated with tree pollen counts in March/April and patient numbers from April through July. Pollen counts in March/April were also correlated with patient numbers from April through July. After adjusting for confounders, including air pollutants, there was a positive association between the minimum temperature in March and hospital visits of patients with tree pollen allergy from April to July(odds ratio, 1.14; 95% CI 1.03 to 1.25).</p> <p>Conclusions</p> <p>Higher temperatures could increase tree pollen counts, affecting the symptoms of patients with tree pollen allergy, thereby increasing the number of patients visiting hospitals.</p

Threat of allergenic airborne grass pollen in Szczecin, NW Poland: the dynamics of pollen seasons, effect of meteorological variables and air pollution

The dynamics of Poaceae pollen season, in particularly that of the Secale genus, in Szczecin (western Poland) 2004–2008 was analysed to establish a relationship between the meteorological variables, air pollution and the pollen count of the taxa studied. Consecutive phases during the pollen season were defined for each taxon (1, 2.5, 5, 25, 50, 75, 95, 97.5, 99% of annual total), and duration of the season was determined using the 98% method. On the basis of this analysis, the temporary differences in the dynamics of the seasons were most evident for Secale in 2005 and 2006 with the longest main pollen season (90% total pollen). The pollen season of Poaceae started the earliest in 2007, when thermal conditions were the most favourable. Correlation analysis with meteorological factors demonstrated that the relative humidity, mean and maximum air temperature, and rainfall were the factors influencing the average daily pollen concentrations in the atmosphere; also, the presence of air pollutants such as ozone, PM10 and SO2 was statistically related to the pollen count in the air. However, multiple regression models explained little part of the total variance. Atmospheric pollution induces aggravation of symptoms of grass pollen allergy