Between August and October an increasingly higher number of people are affected by a respiratory allergic syndrome caused by ragweed pollen (Ambrosia artemisiifolia), a non-native and weedy plant from North America. It’s one alien species invasive that it creates health problems with very severe allergic symptoms in sensitive subjects: sneezing, rhinitis, eye irritation and asthma attacks. Furthermore, the Ambrosia genus produces different types of organic compounds capable of inhibiting the germination and growth of other plants, therefore the presence of Ambrosia artemisiifolia also causes damage to crops especially corn, sunflower and soy.
A worrying aspect is that the proliferation of this plant and its emission of pollen are favoured from the increase in CO2 and temperaturesand therefore by climate change. Pollen tends to deteriorate, rapidly releasing allergens in the presence of high concentrations of nitrogen dioxide (NO2) And ozone (OR3), pollutants typical of urban areas: this causes theincreased risk of allergies in large cities: recent studies indicate that the phenomenon is increasing in the Po Valley, where at least 16% of the population suffers from ragweed allergy.
What is ragweed, where does it come from and when does it bloom
THE’ambrosiabelonging to the Asteraceae family, is an annual herbaceous plant from 20 cm to over 1 m tall with yellowish-green inflorescences. The male inflorescences produce large quantities of pollen which are dispersed into the air. After a rain, pollen fragments into smaller particles that are inhaled even more easily. A plant can also produce 2.5 billion pollen grains and about 60,000 seeds. The latter are very resistant and can germinate even after 40 years. It is a very resistant plant, especially to heat and its proliferation is favored by sunny, open and shade-free environments, on stony ground and arid and degraded soil. It adapts well to urban environments and grows on roadsides, traffic islands, abandoned industrial areas, squares, car parks and construction sites. Outside urban areas it easily multiplies in uncultivated fields, along railway lines or along embankments.
Ambrosia it arrived in Europe from North Americaaccidentally transported together with foodstuffs, especially cereals. It initially spread in the Baltic countries and then spread throughout Europe. It has been present in Italy since the early twentieth century: currently the Milanese area And the areas west of Milan they are the most infested in Italy and among the most contaminated in Europe. The plant flowers in early August and causes allergies from the end of August until the end of September or October.
How to control the species
The species cannot be eradicated completely, but it can be controlled if it is eradicated consistently and repeatedly between April and July of each year before the inflorescences and then the seeds develop. In particular, two mowings of the herbs should be carried out, the first within the last week of July and the second between the middle and the end of August. Chemical weed control is often used in crops. Recently it is being tested as a biological control agent of the species Chrysomelid beetle (Ophraella communa), also of North American origin, which feeds on ambrosia.
Useful precautions in case of allergy
The ATS of the Metropolitan City of Milan and other local social and healthcare companies provide the following practical advice to reduce exposure to ragweed pollen.
- Check the pollen reports on specific apps. Precisely in relation to the increase in pollen allergies in Italy, a monitoring network called POLLNet which has the task of monitoring the quality of the air also in relation to the biological components present in dispersion in the aerosol in the atmosphere.
- Avoid going outdoors when concentrations are high. Pollen concentrations increase on dry and windy days.
- Avoid going out immediately after a rain because the pollen particles fragment and enter the respiratory tract more easily.
- During periods of greater pollen concentration, keep the windows and windows of the car closed using the air conditioner.
- After outdoor activities, remove pollen from clothing, skin and hair.
- Dust often and use a vacuum cleaner to remove pollen from surfaces.
- Use dust masks and dark glasses when working outdoors to reduce inhalation and increased eye discomfort from the sun.
- Avoid smoking which increases irritation of the mucous membranes and respiratory tract.
Pharmacological therapies and the use of antihistamines instead, they must be prescribed by a doctor also following the appropriate International Guidelines.
