Got pollen allergies? Light pollution might make them worse

allergy: The inappropriate reaction by the body’s immune system to a normally harmless substance. Untreated, a particularly severe reaction can lead to death.

asthma: A disease affecting the body’s airways, which are the tubes through which animals breathe. Asthma obstructs these airways through swelling, the production of too much mucus or a tightening of the tubes. As a result, the body can expand to breathe in air, but loses the ability to exhale appropriately. The most common cause of asthma is an allergy. Asthma is a leading cause of hospitalization and the top chronic disease responsible for kids missing school.

average: (in science) A term for the arithmetic mean, which is the sum of a group of numbers that is then divided by the size of the group.

climate: The weather conditions that typically exist in one area, in general, or over a long period.

climate change: Long-term, significant change in the climate of Earth. It can happen naturally or in response to human activities, including the burning of fossil fuels and clearing of forests.

ecologist: A scientist who works in a branch of biology that deals with the relations of organisms to one another and to their physical surroundings.

ecosystem: A group of interacting living organisms — including microorganisms, plants and animals — and their physical environment within a particular climate. Examples include tropical reefs, rainforests, alpine meadows and polar tundra. The term can also be applied to elements that make up some artificial environment, such as a company, classroom or the internet.

global warming: The gradual increase in the overall temperature of Earth’s atmosphere due to the greenhouse effect. This effect is caused by increased levels of carbon dioxide, chlorofluorocarbons and other gases in the air, many of them released by human activity.

hibernation: A state of inactivity that some animals enter to save energy at certain times of year. Bears and bats, for example, may hibernate through the winter. During this time, the animal does not move very much, and the use of energy by its body slows down. This eliminates the need to feed for months at a time.

high school: A designation for grades nine through 12 in the U.S. system of compulsory public education. High-school graduates may apply to colleges for further, advanced education.

immunology: The field of biomedicine that deals with the immune system. A doctor or scientist who works in that field is known as an immunologist.

light pollution: The intrusion of unwanted light into areas that would naturally remain dark. Light pollution interferes with our ability to view the night sky. It also alters the circadian rhythms of plants, animals and people.

link: A connection between two people or things.

migration: (v. migrate) Movement from one region or habitat to another, especially regularly (and according to the seasons) or to cope with some driving force (such as climate or war). An individual that makes this move is known as a migrant.

novel: Something that is clever or unusual and new, as in never seen before. (in literature) A work of fiction.

phenology: The study of periodic and seasonal phenomena in wildlife (such as when birds migrate or flowers bloom). Some of these studies focus on how one type of event (such as bloom dates) line up with another phenomenon, such as the normal arrival in a location of a pollinator for those flowers.

pollen: Powdery grains released by the male parts of flowers that can fertilize the female tissue to make a seed. Pollinating insects, such as bees, often pick up pollen that will later be eaten.

population: (in biology) A group of individuals (belonging to the same species) that lives in a given area.

random: Something that occurs haphazardly or without reason, based on no intention or purpose. Or an adjective that describes some thing that found itself selected for no particular reason, or even chaotically.

risk: The chance or mathematical likelihood that some bad thing might happen. For instance, exposure to radiation poses a risk of cancer. Or the hazard — or peril — itself. (For instance: Among cancer risks that the people faced were radiation and drinking water tainted with arsenic.)

spore: A tiny, typically single-celled body that is formed by certain bacteria in response to bad conditions. Or it can be the single-celled reproductive stage of a fungus (functioning much like a seed) that is released and spread by wind or water. Most are protected against drying out or heat and can remain viable for long periods, until conditions are right for their growth.