Rhinitis is a very frequent disease affecting between 20 percent and 50 percent of the global population depending on the countries and definitions used. Often considered as a trivial disease, rhinitis does actually have an important impact on quality of life; however, very little is known about air pollution as risk factor for rhinitis and its severity in adults.
How do pollen particles provoke allergic reactions? A study in The Journal of Experimental Medicine puts some of the blame on bioactive molecules that are released from pollen. These molecules bind to immune cells and cause them to launch a typical allergy-promoting immune response. Pollen from plants exposed to air pollutants produce more of these allergy-provoking compounds than do pollen from unpolluted areas, possibly explaining why allergies are more prevalent in places with high levels of car exhaust emissions.
Each spring, summer, and fall, tiny particles are released from trees, weeds, and grasses. These particles, known as pollen, hitch rides on currents of air. Although their mission is to fertilize parts of other plants, many never reach their targets. Instead, they enter human noses and throats, triggering a type of seasonal allergic rhinitis called pollen allergy, which many people know as hay fever or rose fever (depending on the season in which the symptoms occur). Of all the things that can cause an allergy, pollen is one of the most widespread.
As if the sneezing and watery eyes were not bad enough, researchers have found that airborne components of diesel engine exhaust significantly worsen allergy symptoms in people with a certain genetic makeup. Researchers from the Keck School of Medicine of the University of Southern California and the David Geffen School of Medicine at UCLA have found that genetic characteristics seen in about half the population leave allergy-sufferers particularly susceptible to the effects of diesel particles.
Residents of the southern United States and the Caribbean have seen it many times during the summer months -- a whitish haze in the sky that seems to hang around for days. The resulting thin film of dust on their homes and cars actually is soil from the deserts of Africa, blown across the Atlantic Ocean.