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Is Sidewalk Chalk Bad for the Environment?

Sidewalk chalk shows up at just about every charity run, music festival, chalk art, and community event. It’s a fun way to express yourself and it’s practically disposable and biodegradable. When the festival is over, you wipe away your art and toss the rest in the trash. But how does it affect our environment? Is sidewalk chalk bad for the environment?

What is sidewalk chalk?

child's drawing  rainbow with colorful chalks on a street

Sidewalk chalk is a popular drawing medium when it comes to festivals and events. It’s typically made from gypsum, which can be found in the soil and water.

It’s a soft, powdery material that is made into sticks and used to draw on sidewalks. Sidewalk chalk can be found in many colors and shades, depending on preference. It typically doesn’t last very long against the elements, especially water.

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Common uses of sidewalk chalk

Sidewalk chalk is used for many different purposes, including advertisement. It’s often found at events to attract people to a booth or table. It’s also used for chalk art by some sidewalk artists.

However, it can also be sold as a parent-child activity. Kids and parents can use sidewalk chalk to draw together and then wipe off the drawings when they’re done.

Sidewalk chalk is also commonly used at charity runs, like the Color Run. Participants can buy colored powder and throw it on themselves, turning them into living artwork for the 5k run.

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What are the main ingredients?

Gypsum, (calcium sulfate) is the main ingredient in sidewalk chalk. Gypsum is usually found in soil, but can also be made artificially to create the powdery substance used to make sidewalk chalk.

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Are there other ingredients?  

Colorful pastel sidewalk chalk placed on road

Many other ingredients may go into sidewalk chalk depending on the product. Some products may use baby oil or wax to help to create multiple colors. If the chalk needs to be stronger against the elements, fertilizer or plasticizers may be used. More natural products are typically safer for our environment.

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Are chalk ingredients biodegradable?

The ingredients in chalk are generally biodegradable. However, the chalk itself may not be if it contains certain additives or plasticizers.

Chalk sticks typically don’t last long against the elements and will wash away with enough rain or puddles of water. If you’re using a product that contains wax or baby oil, that may keep them from breaking down as quickly.

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Is the biodegradable claim legit?  

Young boy drawing on the sidewalk with chalk

Sidewalk chalk can be considered partially biodegradable and partially not. It depends on what ingredients were used to make it and how careful people are about disposing of their art.

Some products may include other ingredients such as vegetable oil or animal fat. These ingredients are not biodegradable and will sit in landfills or rivers forever. However, some products that are made with vegetable oil may be considered biodegradable because of their plant-based ingredients.  

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What happens if it goes away?  

If you idly toss your sidewalk chalk in the trash after using it at a community event, chances are that it will end up in a landfill. However, the gypsum may break down over time due to the elements and will eventually become part of our soil again.

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What about runoff?  

The baby oil ingredients or other ingredients in some sidewalk chalk products can wash away into the sidewalks and ground during rainstorms and goes straight to different bodies of water like rivers and oceans.

This can cause contamination of water supplies and harm aquatic organisms. The long-term effects of this contamination are not completely known.

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Sidewalk chalk vs blackboard chalk

Close up of little girl drawing with chalks on the sidewalk

Sidewalk chalk is different from blackboard chalk. Sidewalk chalk typically uses calcium sulfate, while the other uses calcium carbonate (rock chalk). Both of these can be found in nature, but calcium sulfate is more commonly used to make the powdered material that is used for sidewalk chalk.

Another difference between the two chalks lies in how they are produced. Blackboard chalk is made by grinding up a rock called calcium carbonate, typically found in limestone and chalk. This powdery substance is then mixed with water and other ingredients to create the desired product.

Sidewalk chalk can be made from gypsum, which is naturally found in soil or water. It’s a softer, powdery material that is produced into sticks to create the product.

Sidewalk chalk isn’t always 100% biodegradable, but it’s a great way to make art and express yourself at events without having a huge impact on our environment. With careful disposal of your chalk after an event, you can avoid contaminating our local streams and altering water quality.

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What is chalk dust?

green chalk on sidewalk

Chalkdust is a powder substance that can come from chalk either scribed on a board, sidewalk, or wherever else. Chalkdust can be made anywhere and it varies in consistency and size depending on what type of chalk was used to make the dust. Large and thick sticks create more dust.

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Health hazards of chalkdust

Chalkdust can cause skin irritation or allergic reactions in some people. Some chalk dust may be contaminated with heavy metals like mercury, lead, and arsenic that could result in long-term exposure to toxins.

Inhalation of the dust can cause dryness in the throat or respiratory system. It may also cause accelerated aging if the dust is inhaled frequently.

Ingestion of dust can cause gastrointestinal pain. It can result in diarrhea, cramps, and bleeding in extreme cases.  

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Environmental tips using chalk

  • Don’t let chalk dust get on peoples’ faces. Clean dusty surfaces often with a wet towel to minimize the effects of chalk dust.
  • Wear gloves when using any kind of chalk or chalk dust for increased protection against skin irritation. Don’t eat while using chalk dust, and wash your hands after use.
  • If you’re eating food while using chalk, keep some paper towels around to wipe your hands after using the chalk.
  • Use dustless chalk when possible for increased safety.  

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closeup of Colorful sidewalk chalk

Sidewalk chalk is relatively non-toxic and its main ingredient is biodegradable, so is sidewalk chalk bad for the environment? Yes because sometimes it contains other non-biodegradable ingredients.

And when we leave behind the residue after using. Since rainwater will rinse away these residues towards our sewages and straight into local streams and rivers altering water quality and harming aquatic organisms. This is how it affects our environment.

There’s no problem in using chalk since it’s already part of our lives, but the important thing is using it responsibly.

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What is Calcium Sulfate?

A natural fertilizer that can be used as a soil conditioner. It is also used to make plaster for walls and ceilings.
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What is Calcium Carbonate?

A sedimentary rock is composed of the mineral calcite, or calcium carbonate (CaCO 3). Calcite is made up of the skeletal fragments of marine organisms like coral, seashells, plankton, and algae.  
It is used in making fiberglass insulation for attics, concrete blocks, waste disposal units, tile carpet backing, toothpaste, mortar lining of water wells to soften the hard water, kitty litter.
Beads made from calcium carbonate are used as a filtering material in aquariums to keep the water clean, and as an exfoliant in soaps, face masks, and other cosmetic products.

Is chalk Environmentally friendly?

Chalk is generally considered to be environmentally friendly due to its low impact on the environment. It is made from natural materials, primarily calcium carbonate, which is a form of limestone. Additionally, chalk is biodegradable and does not contain any toxic chemicals, making it safe for use in various settings.

How do you make non-toxic chalk?

Non-toxic chalk is a type of chalk that is made without any harmful chemicals. It is typically made using natural materials such as gypsum and calcium carbonate instead of synthetic materials such as petroleum-based chemicals. To make non-toxic chalk, these natural materials are ground into a fine powder and mixed with water to form a paste that is then molded into sticks and dried. Other natural materials such as food coloring or natural pigments can be added to create different colors.

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