Fiberglass manufacturing is a meticulous process that begins with carefully selecting and preparing raw materials like limestone, silica sand, soda ash, borax, magnesite, nepheline syenite, feldspar, kaolin clay, alumina, and cullet (waste glass). These components are batched (measured and mixed) before being introduced into a furnace, where they're melted into molten glass at temperatures around 1,371°C (2,500°F) with stringent temperature control.

The molten glass is then extruded through tiny nozzles, forming fine glass filaments. These filaments bundle into strands called rovings. Depending on the application needs, the rovings may undergo weaving into mats or remain unstructured for insulation purposes.

• For enhanced strength, woven fiberglass mats are coated with resins, allowing them to be molded into various shapes like pools, boats, automotive parts, and more.

The fiberglass manufacturing process involves selecting optimal raw ingredients, melting them at scorching temperatures, extruding the molten glass into hair-thin fibers, bundling these fibers into strands (rovings), optionally weaving the rovings into mats, and finally, coating the woven mats with resins for rigidity.

Precision controls every step to yield this versatile, lightweight, yet robust composite material ubiquitous across countless industries.

To manufacture top-notch fiberglass products that address "how fiberglass is manufactured," we must meticulously follow the exacting steps outlined – from raw material selection and high-temperature melting to fiber extrusion, strand bundling, weaving (if required), and resin application for the intended strength and shape.

Fiberglass is a synthetic material made from extremely fine glass fibers, and while it offers excellent insulation properties and cost-effectiveness, direct exposure to it can be potentially harmful to human health. We can summarize the potential toxicity of fiberglass material as follows:

Fiberglass fibers can irritate the skin, eyes, throat, and respiratory system upon contact or inhalation. When working with fiberglass insulation, protective equipment such as respirators, goggles, long sleeves, and gloves is essential to reduce exposure. The fine fibers can penetrate the skin, causing itching, rashes, and irritation. Additionally, airborne fibers can irritate the eyes, nose, and throat, leading to coughing, wheezing, and respiratory discomfort, exacerbating conditions like asthma or bronchitis.

While fiberglass is not definitively classified as a carcinogen, some studies have linked prolonged exposure to an increased risk of lung cancer in animals. However, the evidence for carcinogenic effects in humans remains inconclusive. Nevertheless, it's prudent to minimize unnecessary exposure to airborne fiberglass fibers.

Furthermore, fiberglass insulation can release fibers into the air as it degrades over time, posing a risk of inhalation and contamination. Proper maintenance, ventilation, and handling procedures are crucial to mitigate this hazard.

To mitigate potential health hazards associated with fiberglass material, we recommend:

• Utilizing protective equipment (respirators, goggles, long sleeves, and gloves) when handling fiberglass insulation.
• Ensuring proper ventilation and following safety protocols during installation, maintenance, or removal.
• Minimizing unnecessary exposure to airborne fiberglass fibers.
• Embracing a proactive approach to reducing fiberglass exposure.

By taking these precautions and following safety guidelines, the potential risks associated with fiberglass material can be significantly reduced, allowing individuals to benefit from its practical insulation properties while prioritizing their health and well-being.

Fiberglass is a composite material made by combining glass fibers with a polymer resin. While it's neither a resin nor a plastic on its own, it leverages the strengths of both components to create a lightweight yet durable structure.

Here's what you need to know about fiberglass:

• Glass fibers provide reinforcement and strength to the composite.
• The polymer resin acts as a binding agent, encapsulating and protecting the glass fibers.
• When the resin cures or solidifies, it forms a rigid plastic matrix around the glass fibers.

This combination results in a strong, stiff, and lightweight material suitable for various applications due to its exceptional properties:

1. Incredibly strong yet lightweight, ideal for construction, transportation, and sporting goods.
2. Non-conductive, non-magnetic, and chemically resistant, making it useful in electrical and chemical industries.
3. Can be molded into complex shapes, enabling its use in products like bathtubs, boats, aircraft components, and wind turbine blades.

Different types of fiberglass composites exist, tailored to specific requirements. For instance, E-glass fibers are commonly used for electrical insulation, while S-glass fibers offer superior mechanical strength for structural applications. The resin used can also vary, with options like epoxy, polyester, or vinyl ester resins, each offering unique characteristics and performance advantages.

In summary, fiberglass is a powerful union of glass fibers and polymer resin, harnessing the strengths of both materials to create a robust, adaptable, and high-performance composite. When working with fiberglass, it's crucial to carefully consider the application requirements and select the appropriate fiber type and resin matrix to leverage its unique blend of properties effectively.

Fiberglass gets its name from the microscopic glass fibers that form its core material. These ultra-thin glass strands, thinner than human hair, are created by melting glass and forcing it through tiny holes.

We can summarize the key reasons fiberglass contains glass fibers:

• Exceptional strength-to-weight ratio - The glass fibers provide incredible strength despite being lightweight when combined with a polymer resin.
• Versatility in shaping - Fiberglass can be molded into complex curves and intricate shapes ideal for products like boats, cars, and aircraft components.
• Customizable properties - The composition can be tailored for specific needs such as chemical resistance, electrical insulation, or enhanced structural integrity.
• Cost-effectiveness - While not as robust as carbon fiber, fiberglass offers excellent performance at a fraction of the cost, making it economically viable across diverse industries.

The microscopic glass fibers interwoven with resin give fiberglass its outstanding durability, malleability, and cost-effectiveness, making it an indispensable engineering material. Understanding its unique composition and customizable properties is crucial to leveraging fiberglass optimally.

Fiberglass insulation no longer contains formaldehyde, a known carcinogen and respiratory irritant. All major manufacturers in the U.S. and Canada have reformulated their residential products, eliminating formaldehyde-based binders by 2015. This transition was driven by growing awareness of formaldehyde's hazards, market demands for safer alternatives, and stringent standards like the Living Building Challenge's Red List.

The reformulation has significantly reduced formaldehyde emissions from fiberglass insulation factories by a staggering 90% between 2005 and 2014, confirming the industry's commitment to eliminating this toxic chemical from residential insulation products.

While fiberglass insulation is now formaldehyde-free, we should consider other potential hazards:

• Some insulation materials may contain asbestos, flame retardants, or release volatile organic compounds (VOCs).
• Greenguard-certified products and natural alternatives like cotton, wool, hemp, or cellulose are safer options, especially in moisture-prone areas.
• Proper installation is crucial to avoid moisture accumulation, which can lead to off-gassing and structural issues.

Consulting professionals and following guidelines from reputable sources like the U.S. Department of Energy can ensure optimal performance and safety. The fiberglass insulation industry's transition away from formaldehyde offers a compelling example of how market forces, innovation, and transparency can drive positive change. Prioritizing certified, low-emission products and considering natural alternatives will help create a healthier indoor environment.

Yes, fiberglass insulation is still widely used for insulating homes and buildings. It's an effective and cost-efficient thermal barrier that traps pockets of air to slow heat transfer. The manufacturing process involves melting a mixture of materials like silica sand, limestone, and soda ash at extremely high temperatures, then spinning the molten glass into fine fibers that interlock to form insulation batts, rolls, or loose-fill.

While fiberglass has been around for a long time, modern products often incorporate recycled glass content, making them more eco-friendly. Manufacturers have also improved the production process to address potential health concerns related to the tiny glass particles.

Here are some key advantages of fiberglass insulation:

• Excellent thermal insulation properties
• Provides sound-dampening benefits
• Available in various densities for different applications
• Fire-resistant and non-combustible
• Cost-effective compared to some alternatives

To maximize its effectiveness, it's crucial to ensure proper installation and handling techniques. We recommend consulting professionals for guidance on selecting the right fiberglass insulation product and following recommended practices to avoid skin irritation or respiratory issues during installation.

Overall, fiberglass remains a popular choice for insulating homes and buildings due to its performance, affordability, and versatility, especially when installed correctly and with appropriate safety measures.

Fiberglass is a synthetic material. We can confidently state that fiberglass is not natural, as it's manufactured by combining glass fibers with plastic resins.

The process of creating fiberglass involves melting raw materials like silica sand, limestone, and soda ash at extremely high temperatures. These molten materials are then extruded through tiny holes, forming thin glass fibers. These glass fibers are either woven together or arranged randomly to create a fibrous mat.

Next, this fibrous glass mat is combined with a polymer resin (e.g., epoxy, polyester, or vinyl ester). The resin coats and binds the glass fibers, resulting in a strong, lightweight, and durable composite material known as fiberglass.

Fiberglass offers several remarkable properties:

• Exceptional strength-to-weight ratio, making it ideal for applications where minimal weight is crucial (e.g., aerospace, automotive industries).
• Non-combustible and resistant to corrosion.
• Excellent insulator against heat, electricity, and sound.

The manufacturing process involves carefully measuring and mixing raw materials, melting them, extruding molten glass into fibers, and combining these fibers with a polymer resin. This results in a versatile, synthetic composite material with a wide range of applications, from construction and automotive components to boats, aircraft, and sports equipment.

In summary, fiberglass is a synthetic, man-made material composed of glass fibers embedded in a plastic resin matrix. Its unique characteristics, including strength, lightweight, durability, and insulation properties, make it an indispensable material across various industries.

Fiberglass is an excellent fire-resistant material, making it a top choice for applications where heat tolerance and fire safety are crucial. Its components – glass fibers, silica sand, and plastic polymers – are woven together to create a sturdy, heat-insulating structure with trapped air pockets, providing exceptional thermal insulation.

The melting point of fiberglass ranges from 1,000 to 1,400 degrees Celsius (1,832 to 2,552 degrees Fahrenheit), showcasing its high-temperature tolerance. Unlike flammable materials like certain types of foam insulation, fiberglass insulation doesn't readily catch fire, making it practical for environments where heat resistance is essential.

Fiberglass offers several advantages:

• Chemical resistance
• Prevents flames from traveling through it, reducing fire spread
• Abrasion resistance
• High dimensional stability
• Low smoke emission
• Outstanding strength for insulating and high-heat applications

Manufacturers subject fiberglass insulation to rigorous fire-resistance testing and assign specific fire safety ratings. These ratings indicate how well the insulation resists ignition and slows down flame spread in case of a fire.

Fiberglass can be manufactured into various forms, including textiles, blankets, and insulation, thanks to its versatile discontinuous (short) fibers ideal for sound absorption and thermal insulation. This versatility makes it suitable for industries like construction and automotive.

While not entirely fireproof, fiberglass's fire-resistant nature, high-temperature tolerance, chemical resistance, and insulation properties make it an exceptional choice for applications prioritizing fire safety and thermal insulation. Proper installation and adherence to fire safety regulations are crucial for optimal performance and protection.

Fiberglass is an incredibly robust and durable material, making it highly resistant to damage and wear. Its unique composition of glass fibers embedded in a polymer resin matrix gives it exceptional tensile strength, allowing it to withstand immense forces and pressures without breaking or deforming. While fiberglass is remarkably strong, it's also lightweight, making it a versatile choice for various applications.

We can summarize the fragility (or lack thereof) of fiberglass as follows:

• Fiberglass is highly durable and resistant to damage, thanks to its reinforced structure and composition.
• It can withstand significant impacts, pressures, and forces without breaking or losing its structural integrity.
• The material is also resistant to corrosion, UV radiation, and harsh environmental conditions, further enhancing its longevity.
• However, fiberglass can be susceptible to abrasion and scratching if not properly protected or handled with care.

The exceptional strength and durability of fiberglass stem from the strategic arrangement of glass fibers within the polymer matrix. These fibers, oriented in specific patterns, provide incredible reinforcement, allowing the material to withstand immense stresses. Additionally, fiberglass boasts excellent UV resistance, ensuring its longevity even under intense sunlight exposure.

One of the key advantages of fiberglass is its customizability. During the manufacturing process (known as pultrusion), the resin systems and glass content can be adjusted to tailor the material's properties, such as high strength, temperature tolerance, flame retardancy, and corrosion resistance. This versatility makes fiberglass suitable for a wide range of applications, from construction and transportation to chemical processing and marine environments.

So, while fiberglass is not entirely fragile, it's crucial to handle it with care and provide appropriate protection to prevent abrasion or scratches. With its exceptional strength, durability, and customizable properties, fiberglass is a reliable choice for various applications that demand a robust, long-lasting, and lightweight material.

The most common products that use fiberglass are:

• Transportation: Automobiles (body panels, bumpers, interior trims), aircraft (various components), and boats leverage fiberglass for its lightweight strength, corrosion resistance, and formability.
• Construction: Fiberglass reinforced plastics are used in roofing, cladding, pipes, tanks, swimming pools, and hot tubs due to their durability, weather resistance, and seamless surfaces.
• Consumer goods: Sporting equipment (surfboards, fishing rods, recreational vehicles), bathtubs, shower enclosures, and orthopedic casts incorporate fiberglass for its flexibility, impact resistance, and non-corrosive properties.

Fiberglass's versatility stems from its diverse forms – chopped strand mats, woven fabrics, and rovings – combined with different resins like polyester, vinyl ester, or epoxy. This allows tailored properties for optimal performance across various applications. The remarkable strength-to-weight ratio, corrosion resistance, and formability of fiberglass make it an indispensable material in modern product design and manufacturing.

Fiberglass has an abrasive and prickly texture that can irritate the skin, eyes, nose, and throat. Contact with fiberglass can cause an intense, stinging itch accompanied by redness or a rash, as the microscopic fibers can embed themselves in the skin, causing further discomfort. Inhaling airborne fiberglass particles can trigger coughing, wheezing, and respiratory distress, especially for those with pre-existing conditions like asthma or bronchitis, as the fibers can lodge in the nasal passages, throat, and lungs, leading to burning sensations and inflammation.

To address fiberglass irritation, we recommend the following steps:

• Flush the affected area with water.
• Use adhesive tape to gently pull out visible fibers from the skin.
• Apply soothing creams or corticosteroids to alleviate persistent itching or dermatitis.
• Seek medical attention if symptoms persist or worsen.

Preventing exposure is crucial. We advise wearing protective gear, ensuring proper ventilation, and avoiding activities that generate fiberglass dust. Exercising caution and taking proactive measures can minimize the unpleasant and potentially harmful effects of fiberglass contact.

In summary, fiberglass's prickly and abrasive nature demands vigilance and prompt action to mitigate its irritating effects on the skin, eyes, and respiratory system. Implementing safety measures and seeking medical attention when necessary can effectively address the discomfort and potential health risks associated with fiberglass exposure.

Fiberglass can be waterproof when combined with the right resin. While fiberglass itself isn't waterproof, it becomes watertight when saturated with vinyl ester or epoxy resin. Here's what you need to know:

• For constant water exposure or submersion (like boat hulls or pools), vinyl ester or marine-grade epoxy resins are recommended. These resins create a robust water barrier, preventing moisture from penetrating the fiberglass composite.
• Polyester resin, though more economical, may allow some moisture ingress over time and is better suited for surfaces without standing water.
• The waterproofing capability stems from the resin fully encapsulating the fiberglass strands, forming an impermeable composite material. The resin acts as the waterproof matrix, while the fiberglass provides strength and reinforcement.
• In boat construction, a gelcoat layer protects the underlying fiberglass/resin composite from UV radiation and environmental factors. However, it's the complete saturation of the fiberglass with the appropriate resin that creates the watertight barrier.

We should note that beyond waterproofing, fiberglass composites offer lightweight yet robust properties, versatility in shaping, and cost-effectiveness compared to metals. These advantages make them suitable for various industries, including construction, automotive, and aerospace.

Fiberglass and steel are both durable materials, but they differ in several key aspects. We'll explore the advantages and disadvantages of each to help you make an informed decision.

In terms of strength-to-weight ratio, fiberglass outperforms steel. It's significantly lighter yet can be up to four times stronger than steel in tensile strength, making it remarkably sturdy and resistant to stretching or breaking under tension. This lightweight yet robust nature makes fiberglass easier to handle, transport, and install, reducing labor intensity and increasing productivity.

One of the most significant advantages of fiberglass is its corrosion resistance. Unlike steel, which can corrode and degrade over time, fiberglass maintains its structural integrity even in harsh environments involving water or salt exposure. This reduces maintenance requirements and potential replacement costs.

Fiberglass also offers exceptional energy efficiency and insulating properties. Fiberglass doors and structures effectively prevent air leakage, contributing to reduced heating and cooling costs, making them an environmentally-friendly and cost-effective choice.

• Customizability: Fiberglass allows for a wide range of finishes, colors, and textures, including realistic wood grain imitations, enabling seamless integration with various architectural styles and personal preferences.

On the other hand, steel's primary advantage is its sheer strength and security. Steel doors and structures are virtually impenetrable, offering superior protection against forced entry attempts. While fiberglass is a secure option, steel remains the undisputed champion in terms of fortification.

1. Initial Cost: Steel is generally more affordable than fiberglass in terms of initial costs, making it an attractive choice for budget-conscious projects.

However, it's crucial to consider the long-term maintenance requirements and potential corrosion issues associated with steel, which may offset the upfront cost savings.

In summary, if strength, durability, energy efficiency, customizability, and low maintenance are paramount, fiberglass emerges as an excellent choice. Conversely, if maximum security and affordability are the primary concerns, steel may be the preferred option. Evaluate your specific priorities and requirements to make the best decision for your needs.

Fiberglass and carbon fiber are both lightweight, strong composite materials, but they differ in several key aspects. Carbon fiber is stronger, stiffer, and more lightweight than fiberglass, making it ideal for applications that require exceptional strength and rigidity, such as aerospace components and precision scientific instruments. On the other hand, fiberglass is more flexible, less expensive, and dimensionally stable at varying temperatures, making it a popular choice for applications like boat hulls and drainage systems.

While both materials are corrosion-resistant and perform well in chemically challenging environments, carbon fiber has superior conductivity properties, making it suitable for applications that involve electromagnetic shielding or electrical conductivity requirements. In terms of cost, fiberglass is generally more cost-effective than carbon fiber due to its simpler production processes and widespread adoption.

When choosing between these two materials, consider the following key factors:

• Strength and rigidity requirements: Carbon fiber is significantly stronger and stiffer than fiberglass, with a tensile strength of 500 ksi compared to 300 ksi for fiberglass.
• Weight considerations: Carbon fiber has a higher strength-to-weight ratio, making it ideal for applications where weight is a critical factor.
• Flexibility needs: Fiberglass is more flexible than the rigid carbon fiber, making it suitable for applications that require pliability.
• Cost constraints: Fiberglass is generally less expensive than carbon fiber due to its simpler production processes.
• Environmental factors: Both materials are corrosion-resistant and perform well in chemically challenging environments, but carbon fiber has superior conductivity properties.

By understanding the unique properties and characteristics of fiberglass and carbon fiber, you can make an informed decision on which material best suits your specific application and performance requirements.

Fiberglass is an exceptionally strong material for its lightweight nature. We'll explore why fiberglass is so robust and its various applications.

Fiberglass comprises plastic reinforced with glass fibers, creating a durable and impact-resistant structure. The glass fibers provide tensile strength, while the plastic matrix offers flexibility and resilience. Each glass fiber is remarkably thin yet immensely strong, contributing to fiberglass's exceptional strength-to-weight ratio. These fibers can be arranged randomly or woven into fabric, then combined with a polymer resin to form a solid, molded shape. The resulting product boasts impressive pound-for-pound strength, often surpassing that of steel.

Moreover, fiberglass's corrosion resistance makes it ideal for harsh environments, outperforming traditional materials like metal. Its thermal insulation properties further enhance its versatility across industries. From construction and automotive applications to boats and aircraft, fiberglass's unique blend of strength, lightweight, and durability makes it an indispensable material.

The pultrusion manufacturing process allows for continuous production of complex, customized fiberglass shapes with tailored properties. This process aligns the fibers longitudinally, maximizing strength in the desired direction while maintaining a lightweight profile.

• Exceptional strength-to-weight ratio
• Corrosion resistance
• Thermal insulation properties
• Versatility across industries
• Customizable shapes and properties

To properly leverage fiberglass's exceptional strength, consider its specific application requirements, desired shape complexity, and environmental conditions – this versatile material can be customized to meet a wide range of demanding specifications.

No, fiberglass is not as bad as asbestos. While both materials consist of thin, fibrous strands that offer heat-resistant and insulating properties, fiberglass is generally considered a safer alternative to the more hazardous asbestos. Here's a concise overview:

• Asbestos is a naturally occurring mineral classified as a proven human carcinogen, with prolonged exposure leading to severe respiratory illnesses like lung cancer and mesothelioma.
• Fiberglass, on the other hand, is a synthetic, inorganic material made from glass reinforced by fine fibers. Extensive research over the past 25 years suggests no substantial evidence linking fiberglass insulation exposure to adverse health risks like cancer.
• Both materials can cause skin and eye irritation upon direct contact, but asbestos fibers become hazardous when disturbed and released into the air, where they can be inhaled or ingested, posing a more significant health risk.

While fiberglass poses some risks when mishandled, it is widely considered a more viable option for various applications due to its relatively lower health hazards and versatile properties. Proper handling precautions should be taken when dealing with either material to mitigate potential risks effectively.

Fiberglass is an incredibly useful material, but its tiny shards can cause intense itching and skin irritation. We'll explain why fiberglass is itchy and provide tips on how to alleviate the discomfort.

Fiberglass is itchy because it consists of microscopic splinters that penetrate the skin, triggering an immune response and histamine release. This mechanical irritation leads to redness, rash, and in severe cases, blisters or swelling from an allergic reaction.

To alleviate the itchiness, follow these steps:

• Promptly remove any clothing contaminated with fiberglass fibers to prevent further exposure.
• Thoroughly wash the affected area with warm water and mild soap to dislodge surface fibers.
• For stubborn embedded shards, gently apply masking tape and peel it off – the fibers will adhere to the adhesive.
• Rinse with a rich hair conditioner (like Pantene Pro-V) to help coat and lift fibers from the skin.

Over-the-counter corticosteroid creams can also alleviate inflammation and discomfort. However, avoid scratching the affected area, as this can drive fibers deeper into the skin.

Prevention is key when dealing with fiberglass. Here are some preventive measures to take:

• Wear protective garments, masks, and goggles when handling fiberglass.
• Ensure proper ventilation to minimize inhalation of airborne particles.

If symptoms worsen or indicate an infection, seek medical attention immediately. With diligent precautions and prompt treatment, the misery of fiberglass itch can be managed effectively.

Fiberglass can be harmful to humans, potentially causing skin irritation, eye irritation, and respiratory issues. The tiny fibers act as an irritant when they come into contact with the skin, eyes, or are inhaled, leading to dermatitis, coughing, wheezing, and breathing difficulties.

While not classified as a confirmed human carcinogen, some studies suggest a potential link between fiberglass fiber exposure and an increased cancer risk, particularly in animal studies. However, the evidence is inconclusive, and the risk may depend on factors like fiber type, exposure duration, and individual susceptibility.

Inhalation of fiberglass fibers is a primary concern, as they can reach the lower respiratory tract and cause irritation or other respiratory problems. Those with pre-existing conditions like asthma may be more sensitive to exposure.

Ingesting fiberglass fibers can also lead to severe stomach pain and irritation, making it crucial to avoid ingesting any particles.

Proper precautions should be taken when working with or around fiberglass insulation:

• Wear protective gear (respirators, goggles, long sleeves, and gloves) to minimize exposure.
• Ensure adequate ventilation and avoid disturbing installed insulation to reduce fiber release and contamination.

While fiberglass insulation offers practical benefits, it's essential to recognize its potential health hazards and take appropriate measures to mitigate exposure. Proper handling, installation, and maintenance are key, and considering sustainable alternatives like cellulose or sheep's wool insulation may be safer options.

When looking for a fiberglass-free mattress, there are several certifications and labels to consider. We recommend prioritizing mattresses with the CertiPUR-US®, Oeko-Tex Standard 100, or Global Organic Latex Standard (GOLS) certifications. These certifications ensure low VOC emissions and the absence of harmful substances, including fiberglass.

However, it's essential to scrutinize mattress labels and product descriptions carefully. Look for clear disclosures of materials, and be wary of vague terms like "fire barrier" or "flame retardant," as these could potentially indicate the presence of fiberglass. If a mattress label lacks transparency regarding fire-resistant materials, don't hesitate to contact the manufacturer directly for clarification.

• The CertiPUR-US® certification primarily focuses on foam components, so a mattress with this certification may still contain fiberglass in other components.
• The Oeko-Tex Standard 100 certification tests every component of the mattress, including textiles and foams, for potentially harmful substances.
• The GOLS certification ensures all raw materials used in the manufacturing process are organic, making it an ideal choice for those seeking fiberglass-free, organic latex mattresses.
• Mattresses made with natural materials like organic wool, cotton, or hybrid constructions are commonly free from fiberglass, as they prioritize using natural fire retardants.

Transparency from manufacturers and retailers is crucial. By actively seeking reputable certifications and demanding clarity in material disclosures, you can make an informed decision and rest assured that your mattress is free from fiberglass and other potentially harmful substances.