1
Due date:
Science Safety Current Events
Name: ________________________________________________
Science resource name: Science News for Kids
Date: _____________________
Article name: Sniffing for bad air
Period: _________
Handheld carbon dioxide sensor can help identify classrooms with unhealthy ventilation rates
*Directions: Step1. Read the article. Step 2. Locate, Identify and underline and highlight individually the key points / main ideas, article
name, author, and important figures (people mentioned) important figure careers. Step 3. Answer the reflection questions. Step 4.
Make a unit connection and inference with the unit fact sheet. Always use a sentence stem such as “According to the article” …….
By Sid Perkins / September 14, 2012
*Tips: Remember to include the (What, when, why, who, and how) in the summary.
The air quality in many classrooms is unhealthy, due to poor ventilation. But simple solutions such as opening a window can help get rid of bad air.
Credit: i_love_zou_york/iStockphoto
In the past few weeks, millions of students, teachers and staff have returned to classrooms in schools across the United
States. The air quality in many of those classrooms might be unhealthy, thanks to poor ventilation. But a new sensor
designed to identify elevated amounts of carbon dioxide could help solve the problem — and maybe even boost test scores,
scientists report.
The handheld device developed by a chemist and his colleagues is easy to use: Simply carry it into a room where you want
to measure carbon dioxide levels. Once bad air is detected, the solution might be as easy as opening a window.
With every breath you take, you inhale a host of gases, including oxygen. Every time you exhale, you breathe out carbon
dioxide (CO2). Both of these gases are a natural part of Earth’s atmosphere.
Nitrogen makes up more than 78 percent of the air; oxygen almost 21 percent. Meanwhile, CO 2 makes up only a tiny fraction
of Earth’s atmosphere: 0.0395 percent. That means that a mere 395 molecules out of every million in the air are CO 2. Yet
even though that proportion, or concentration, of this gas in the air is very low, CO 2 is very important. Plants use it to grow
and make oxygen, which humans and all other animals require.
Odorless and colorless, CO2 comes from many sources. These include volcanoes, rotting vegetation and the burning of fossil
fuels such as gasoline, natural gas and coal. Animals also produce CO 2 when inhaled oxygen reacts chemically with carbon
in the foods they consumed. The average person breathes out between 20 and 25 liters of CO 2 each hour.
When a large number of people spend time in an enclosed space like a classroom, CO 2 concentrations can increase
dramatically. This is particularly true if air circulation is poor, explains Jack Driscoll. He’s a chemist at PID Analyzers. The
company, based in Sandwich, Mass., makes equipment used to detect and measure various gases in the air.
1
2
Chemist Jack Driscoll holds a new device he helped design that measures concentrations of carbon dioxide. The sensor can be used by school
maintenance personnel to identify poor classroom ventilation.
Credit: PID Analyzers, LLC
When levels of CO2 build up, people may develop headaches or become sleepy, notes Roger Hedrick. He’s an
environmental engineer at Architectural Energy Corporation in Boulder, Colo. Elevated CO 2 levels can be a sign that
ventilation is poor, he notes. And that means that other gases — including noxious, or harmful, ones — might be building up
as well. What types of other gases? It could be something as simple as body odor. Or it could be something as potentially
dangerous as solvents and other volatile organic chemicals, often referred to as VOCs. These can be emitted by furniture,
carpets or paints.
In schools built 15 years ago or more, air in a typical classroom is fully replaced with fresh air between four and six times
each hour, says Driscoll. Surprisingly, he notes, the air in some newer schools may be replaced with fresh air only once or
twice each hour. The reason: Buildings designed to be energy efficient are more tightly sealed, to lessen the loss of heated or
cooled air. This also lessens, however, the removal of any unhealthy air. So exchanging indoor air with air from outdoors can
often lower pollutant levels.
The Environmental Protection Agency doesn’t set standards for CO 2 concentrations in schools, office buildings or commercial
properties such as department stores or shopping malls, says Hedrick. But a professional group called ASHRAE has
developed guidelines for many aspects of indoor air quality, including CO 2 levels. (Hedrick is the current chairman of the
ASHRAE committee that developed these recommendations.) According to those guidelines, CO 2 concentrations in a
classroom should not rise above 1,025 parts per million. That’s about 2.5 times the average concentration of CO 2 in outdoor
air.
To help identify stale classroom air, Driscoll and his colleagues developed a device that can easily be used to monitor CO 2
concentrations. The walkie-talkie-sized device constantly slurps in air samples. Electronics in the sensor measure the
amounts of infrared light absorbed by the air sample at two different wavelengths. One is a wavelength at which CO 2 absorbs
little if any of the light. At the other wavelength, the gas absorbs a lot of the light. Comparing the light’s absorption at these
two different wavelengths provides a measurement of the concentration of CO2 present in a room’s air.
Driscoll described this new CO2 sensor on August 22 at the American Chemical Society meeting in Philadelphia. If the sensor
detects that CO2 levels have reached unacceptable limits, then the remedy is often very simple, he notes. For example,
school maintenance personnel can often increase classroom ventilation simply by changing dirty air filters or adjusting the
speed of the blowers in the school’s heating or air-conditioning system. And the simplest solution at all: For a short time,
room windows can be opened slightly.
Besides improving classroom air quality, increasing ventilation could help boost student performance, Driscoll and his
colleagues contend. Many previous studies have shown that improved air quality is linked to better test scores, he notes.
2
3
Main Idea Summary: __________________________________________________________________________________
___________________________________________________________________________________________________________
___________________________________________________________________________________________________________
___________________________________________________________________________________________________________
___________________________________________________________________________________________________________
___________________________________________________________________________________________________________
___________________________________________________________________________________________________________
___________________________________________________________________________________________________________
___________________________________________________________________________________________________________
___________________________________________________________________________________________________________
____________________________________________________________________________________________________________
____________________________________________________________________________________________________________
___________________________________________________________________________________________________________
Unit Inference connection Summary
____________________________________________________________________________________________________________
________________________________________________________________________________________________________________________ _
____________________________________________________________________________________________________________
____________________________________________________________________________________________________________
____________________________________________________________________________________________________________
____________________________________________________________________________________________________________
____________________________________________________________________________________________________________
____________________________________________________________________________________________________________
____________________________________________________________________________________________________________
____________________________________________________________________________________________________________
____________________________________________________________________________________________________________
_____________________________________________________________________________________________________________
3