Skip to content

Pollution

Cities Change Wind Patterns, Raising Pollution

by Melanie J. Martin 08 Jun 2011
Cities Change Wind Patterns, Raising Pollution

Researchers emphasize the importance of urban planning as they observe how cities inhibit natural air cleansing processes. Two recent studies explored wind patterns in highly polluted cities - Houston, and Ouagadougou, a west African city by the Sahara Desert - to learn how stagnant air affects pollution levels, particularly in warmer weather.

Amongst U.S. cities, Houston has some of the highest levels of pollutants like ozone at the ground level. In Houston, urban development inhibits winds from sweeping pollutants out to the ocean at night, the National Center for Atmospheric Research (NCAR) found. Buildings aren't the only factor, or even the primary one. In fact, it's heat from the pavement that changes wind patterns, making pollution build up in stagnant air. These findings have implications for other midlatitude coastal cities in the U.S. and abroad, say the researchers.

At night, winds are slower than they would be if no cityscape were present, a computer simulation showed. Land in the city remains warmer at night, and in the summer, this causes similarity in land and sea temperatures that in turn slows night winds. Buildings play a large role in slowing air flow in the afternoon.

In some cities, stagnant air especially affects the poor. In Ouagadougou, by the Sahara Desert in west Africa, high dust levels and emissions get trapped in stable layers, say researchers at the University of Gothenburg, Sweden.

This particularly happens in the evening, with pollutants lingering in the air rather than being blown away by winds. In poorer areas this phenomenon has a stronger effect, largely because of dusty, unpaved roads. Older vehicles and cooking over open fires also puts people in poorer areas at risk, with respiratory problems leading to 20 percent of deaths.

"The phenomenon is rather normal among very poor cities around the world," says a press release for the study. Thus, as urban populations rise, planning becomes increasingly more important.

Growth of the city landscape could slow winds and raise pollution even more, making air circulation a primary concern in the design of cities, says the NCAR study's lead author Fei Chen.

Researchers for both studies believe greener areas can improve air quality in these cities. Vegetated areas in Ouagadougou have cooler temperatures at night, suggesting greener areas could play a large role in improving air quality in cities, researchers say. "If you made the city greener and created lakes and ponds, then you probably would have less air pollution even if emissions stayed the same," Chen says of Houston. These landscapes would cool the city and boost air circulation to disperse pollutants.

The NCAR study will be published in the June issue of the Journal of Geophysical Research-Atmospherics.

(Top Image Caption: Paved surfaces in the Houston area keep the city warmer than more natural surfaces. As a result, overnight temperatures are often similar between the city and nearby offshore areas, which weakens summertime breezes and enables air pollution to build up. The stagnant conditions also persist during the day because of larger-scale wind patterns.

Top Image Credit: © UCAR, (Illustration by Lex Ivy)


Trending Eco-Friendly Clothing

Love My Planet Women's Relaxed Fit Hoodie
Earth
Quick Add
Close
Notify me
Notify me
Love My Planet Women's Relaxed Fit Hoodie
Love My Planet women's eco-friendly relaxed fit hoodieSize Guide Centimeters 8 10 12 14 16 18 Bust 84 88 92 97 103 108 Waist 66 70 75 80 85 91 Hips 91 95 99 104 109 116 Bust: Measure around the fullest part of...
£38.00
£38.00
Close
Notify me
Notify me
Penguins Hate Push-Ups Men's Pullover Hoodie
Earth
Quick Add
Close
Notify me
Notify me
Penguins Hate Push-Ups Men's Pullover Hoodie
Penguins Hate Push-Ups men's eco-friendly pullover HoodieSize Guide Centimeters XS S M L XL XXL Height 171 175 179 183 189 195 Chest 86 93 99 104 116 129 Waist 71 76 81 89 99 112 Chest: Measure all round your chest just below...
£38.00
£38.00
Close
Notify me
Notify me
Lightning Bolt Kids Long Sleeve T-Shirt
Earth
Quick Add
Close
Notify me
Notify me
Notify me
Lightning Bolt Kids Long Sleeve T-Shirt
Lightning Bolt kids eco-friendly long sleeve t-shirtSize Guide Centimeters 3-4yrs 5-6yrs 7-8yrs 9-10yrs 11-12yrs Height 98 112 125 136 147 Chest 60 66 70 75 84 Chest: Measure all around your chest just below your armpits. Height: Your natural height If you fall between...
£18.00
£18.00
Close
Notify me
Notify me
Notify me
Union Jack Tote Bag
Earth
Quick Add
Close
Notify me
Notify me
Union Jack Tote Bag
Union Jack eco-friendly colour tote bagProduct Specification Organic Cotton Tote Bag. Twill Weave (170gsm). 37 x 42 cm (7cm gusset.) Made in India / Designed on the Isle of Wight. Wash Cool, Hang Dry.
£16.00
£16.00
Close
Notify me
Notify me
Prev Post
Next Post

Eco-Friendly Shop

Women's Clothing

Eco-Friendly Clothing for Women Our online shop offers a wide range of sustainable women’s clothing products, including t-shirts, hoodies, vests, sweaters, shorts, and...
Shop Now

Men's Clothing

Eco-Friendly Clothing for Men Our online shop offers a wide range of sustainable men’s clothing products, including t-shirts, hoodies, vests, sweaters, shorts, and...
Shop Now

Kids Clothing

Eco-Friendly Clothes for Kids Our online shop offers a wide range of sustainable kids clothing products, including t-shirts, hoodies and jumpers. Our garments...
Shop Now
Someone recently bought a
[time] ago, from [location]

Thanks for subscribing!

This email has been registered!

Shop the look

Choose Options

Earth Times
Sign up for exclusive updates, new arrivals & insider only discounts

Recently Viewed

Edit Option
Back In Stock Notification
this is just a warning
Login
Shopping Cart
0 items

Before you leave...

Take 20% off your first order

20% off

Enter the code below at checkout to get 20% off your first order

CODESALE20

Continue Shopping