Air Quality: Fact or Fiction?
Learning something new always raises a few questions. As students learn more about air quality – it’s a great time to consider some common thoughts about the air and whether they are, indeed, facts.
Air quality isn’t as bad during the winter.
Fact: Cooler air in winter can trap pollutants. Winter months are known as inversion months. Inversion is caused by warmer air moving over cooler, denser air, which stays trapped – keeping the cooler air closer to the earth’s surface. When that happens, particles in the air have a harder time dispersing (spreading) and stay closer to the ground, too. Inversions can continue for hours – even days.
Temperature affects air quality.
Fact: Temperature plays a role in the quality of the air. During hotter days in the summer, for example, the air closer to the earth’s surface can be much warmer than the air above. Sometimes large volumes of this warm air will rise and mix with the air farther away from the earth’s surface. When a small amount of polluted air mixes with a large amount of clean air, it can help disperse the pollution – leading to cleaner air.
The rain washes the air.
Fact: Rain can “wash” the dirt away. Precipitation, especially rain, improves air quality by capturing particles and dissolving gases on its way to the earth’s surface.
I live next to a park – the air must be good.
Fact: Particles in the air travel. Tiny particles in the air have the ability to travel for long distances because of the wind. Air pollution doesn’t stop at country borders. If a large fire or natural disaster is making the air more polluted in one place, those particles can travel to other places and impact the air quality there, too – even across oceans!
Wind, temperature, precipitation and topography, individually and together, can all impact air quality. If you live in a valley, surrounded by mountains – sometimes air can get trapped in that area. Wind can help disperse pollution (make it spread) and rain can help improve air quality.
Since air pollution is usually invisible to the naked eye, the Air Quality Flags help tell us what kind of air day it is – to help students, teachers, and parents think about air, its connection to health, and how to be better stewards of the air.
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Source: BC Ministry of Environment website