2.2 Radon (II) - Health effects, measurement and control

Loading...

En provenance du cours de The Hong Kong University of Science and Technology

Introduction to Indoor Air Quality

37 notes

The Hong Kong University of Science and Technology

Introduction to Indoor Air Quality

37 notes

Course Overview: https://youtu.be/LLVb4FOn4uU This course provides a basic knowledge of an emerging area – Indoor Air Quality (IAQ) in buildings. Learners will realize the importance of maintaining proper IAQ. Characteristics associated with indoor air contaminants (IAC) are demonstrated, such as • Particulate matters (PM2.5, PM10) • Radon • Volatile organic compounds (VOCs) • Asbestos • Bio-aerosols, and more Safe exposure levels, resulting health effects, measurement techniques, mitigate and control measures of these IAC are discussed. Other important areas related to IAQ such as building ventilation systems, indoor flow characteristics, sick building syndrome, and thermal comfort are also covered in this course.

À partir de la leçon

Radon and Indoor Aerosol

In this module, two major Indoor Air Contaminants - Radon and Indoor Aerosol are discussed. Their properties, sources, health impacts, mitigation and control measures are explained. Besides, we will look into another effective method to improve IAQ - Use of Air Cleaners. Some industries, such as pharmaceutical and semiconductor manufacturing, require very high cleanliness indoor environments. We will look into how professionals build cleanrooms for these industries.

2.1 Radon (I) - Introduction to Radon4:47

2.2 Radon (II) - Health effects, measurement and control6:52

Rencontrer les enseignants

Christopher Chao
Adjunct Professor
Department of Mechanical and Aerospace Engineering
Edwin Tso
Research Assistant Professor
Department of Mechanical and Aerospace Engineering

Hello everyone.

In this video, we will continue to discuss radon.

As mentioned in our previous video, the decay chains show that radon is mainly produced

by the decay of uranium.

Radon is one of the common elements in soil and rock.

The radon released from soil and rock may spread to the air and surrounding water source.

So it is possible to find radon in the water supply.

Diffusion and pressure induced flow are the main ways for radon to flow from underground

to the surface.

Building materials made of concrete also emit radon to the indoor environment.

Besides, burning fossil fuels, like natural gas release radon to the surrounding environment.

Radon can enter buildings through several ways.

As mentioned, water supplied to the buildings may contain radon.

Besides, radon can release from the building materials when there are cracks on the walls,

and ceilings.

Moreover, radon from the air and soil can flow into the buildings by windows, drains,

and even via ventilation systems.

After getting into a building, radon stays inside the building and accumulates, so it

is important to remove radon from buildings.

Radon will not cause acute health effects, but exposure in an environment with radon

for a long period of time can increase the risk for lung cancer.

It is the second leading cause of lung cancer while the first one is smoking.

In US, about 20 000 deaths per year are estimated to be caused by radon.

As mentioned in the previous video, radon in the air disintegrate into other radionuclides

called radon daughters.

When we breathe, those radon daughters enter our lungs and perform disintegration processes,

releasing radiation there.

That radiation, such as alpha particles, reacts with lung cells and damages the DNA, eventually

causing lung cancer.

To evaluate the radon concentration, Becquerel per cubic meter and picocurie per liter are

used depending on which unit system you use.

1 Becquerel is equal to 1 disintegration per sec. 1 curie is equal to 37 billion disintegrations

per sec.

So 1 picocurie per liter is equal to 37 Becquerel per cubic meter.

This table shows the number of non-smokers per 1000 people that are estimated to suffer

lung cancer under different radon concentration.

The data comes from the United States Environmental Protection Agency.

It is obvious that increasing the radon level, the possibility to suffer lung cancer is increased.

The optimal condition is to keep the radon level in the environment below 2 picocuries

per liter.

We measure radon in an indoor environment by detecting the emissions of alpha, beta

or gamma during the radioactive decay of radon.

There are four common measurement methods suggested in this video, continuous radon

monitor, alpha-track detector, grab sampling, and charcoal canister.

The radon measurements can be analyzed either at home or at a laboratory.

For the measurements taken at home, the continuous radon monitor is one of the choices.

It is a real time sampling and real time analysis instrument.

It measures the radon concentration by monitoring the electric pulse caused by the radon decay

process.

Alpha track detector is another instrument that can be used at home.

The alpha particles emitted by the radon during decay while air diffuses through the filter

in a container can be detected.

The radon concentration is calculated by the amount of alpha particles detected and the

sampling time.

It needs longer sampling times in order to obtain a more accurate result.

Grab sampling is one of the radon measurement methods that need to be analyzed at a lab.

To perform the sampling, air is drawn into a container filled with activated charcoal.

Then, the container will be transported to a lab for analysis.

For charcoal canister, there are charcoal granules in a container to adsorb radon.

It takes several days for sampling.

It also needs to be analyzed in a lab.

To mitigate and control the radon concentration in an indoor environment, so as to minimize

the effect of radon, several methods are recommended.

First, building materials with concrete that can emit radon as mentioned.

It is suggested to use materials emitting no or less radon for building construction.

Besides, some coatings, such as epoxy resin on the surface of walls and ceiling materials,

can reduce radon emission from the materials.

Sealing the cracks in the walls can also reduce the emission of radon from the building materials.

In addition to source control, to reduce the radon concentration in an indoor environment,

the ventilation rate can be increased to extract radon from the buildings.

The use of air cleaners can also help to filter the radon to reduce its concentration in an

indoor environment.

To conclude, we have introduced the indoor and outdoor sources of radon, and discussed

the health effects of radon.

In addition, we have listed some radon measurement methods.

Finally, we have suggested some methods to reduce the radon concentration in buildings.

Explorer notre catalogue

Rejoignez-nous gratuitement et obtenez des recommendations, des mises à jour et des offres personnalisées.

Coursera propose un accès universel à la meilleure formation au monde, en partenariat avec des universités et des organisations du plus haut niveau, pour proposer des cours en ligne.

© 2018 Coursera Inc. Tous droits réservés.

Télécharger dans l'App Store

Disponible sur Google Play