Revised On: March. 17, 2024 - 8:00 p.m.

Learning Objectives:

• Identify safer paints
• Describe the harmful effects of some paints and vinyl wraps

Painting

Painting carries some of the highest risks to the environment and staff safety. Both paints and paint thinners contribute to health and environmental considerations. This is compounded by automotive paint being applied through spraying. Paints contain pigments, additives, and some kind of solvent.  The immediate concern when using paints are solvents. When paint is mixed, sprayed, or cured, it will be off-gassing some VOCs. Water-based paints can replace all the harmful solvents with water, but most will still have some amount of solvent. The amount of solvent in water-based paints will still be significantly less than in solvent-based paints. In addition, water-based paints are reduced with water and not traditional paint thinners. Paint thinners, which are solvents, are necessary to reduce the paint to get it through spray equipment. Note that ready-to-spray paints will already have the paint thinner mixed in. Common solvents for paint thinners are turpentine, methyl ethyl ketone (MEK), acetone, and naphtha. 

Some automotive paints, particularly older formulations, can contain hazardous heavy metals such as lead, chromium, and cadmium. These metals can leach from paint waste into the soil and water, posing risks to aquatic life and potentially contaminating drinking water sources. In humans, exposure to these heavy metals can lead to various health issues, including developmental problems, neurological damage, and cancer. 

Paint hardeners in two-component systems may contain isocyanates. Isocyanates are required to help cure paint during refinishing operations. The same temperatures used during the manufacturing process to cure paint can’t be used with all of the components of a car installed. Isocyanates add to the health and environmental concerns. They can cause health effects, such as:

• Nose and throat irritation from inhalation
• Skin and eye irritation through contact 
• Continuous exposure can cause sensitization. Further exposure, even small, once sensitized, can cause rashes, asthma, and life-threatening asthma attacks.

The environmental harms of isocyanates come from their toxicity and presence in the environment.

Wraps

Car wraps can be an affordable alternative to painting a car but can contain hazardous materials and contribute to the ever-growing solid waste problem. If the wraps your facility uses are made from Polyvinyl Chloride (PVC), then there is a greater environmental risk associated. PVC can potentially be a hazardous waste if it leaches toxic constituents in excess of the toxicity characteristic leaching procedure (TCLP) regulatory limit. The TCLP is a way to test the potential for the toxic constituents to be released into a landfill. PVC wrap can potentially contain constituents such as vinyl chloride or toxic heavy metals that the TCLP can identify. Chlorine is the building block of CFCs, notorious for harming the ozone layer. Chlorine-based toxins persist in the environment long after they’ve been released, polluting our waterways, soil, and air. Chlorinated toxins bioaccumulate in the fatty tissue of humans and wildlife, making them lifelong residents in our bodies. Many studies show that these chemicals cause a slew of human health effects, from infertility to cancers, impaired childhood development, and more. Additionally, PVC-based products contain a high number of phthalates, a group of chemical compounds that give rigid plastics durability. This group is known to disrupt the human endocrine system, causing hormonal imbalances in both men and women. These man-made compounds can enter the body via inhalation, absorption, and ingestion.

In addition, PVC manufacturing creates hazardous air pollutants. When PVC is burned, dioxins are released, which are highly toxic. They are known as POPs, or persistent organic pollutants, because they, too, take a long time to break down. The EPA has stated that the environment has zero safe level of dioxins. Dioxins can enter drinking water through various means, including air emissions from PVC incineration and other combustion, deposition from air to soils that erode into surface waters used for drinking water, and discharges into water from chemical factories, including those that manufacture PVC. PVC is not biodegradable or recyclable and can take hundreds, if not thousands, of years to break down. 

Wraps made from PET are petroleum-derived and are not a renewable resource.

Management and Disposal

Paint waste and booth filters will generally be regarded as hazardous waste, but the facility must still make this determination.  As discussed in the Introduction to Pollution Prevention module, the Resource Conservation and Recovery Act (RCRA) determines the management standards for hazardous waste. Some regulations come from the National Emission Standards for Hazardous Air Pollutants (NESHAP): Paint Stripping and Miscellaneous Surface Coating Operations at Area Sources.

For RCRA, the most common category for an automotive maintenance facility is a very small quantity generator (VSQG). A VSQG generates less than 220 lbs of hazardous waste in a month and does not accumulate more than 2200 lbs at any time, as stated in Title 40 of the Code of Federal Regulations (CFR) section 262.13. VSQGs have reduced requirements and do not need an EPA ID. The main requirement for VSQGs is that the waste being shipped off-site must go to a permitted treatment, storage, or disposal facility (TSDF). This ensures that the waste is handled properly through its end-of-life management instead of improperly disposed of in a landfill. Hazardous waste will come from leftover paint, paint thinners, hardeners, and from maintenance/cleaning of spray equipment. Hazardous waste generation can be increased unnecessarily when a listed hazardous waste, such as some mixed solvents, is mixed with a non-hazardous waste, such as water; the resulting mixture is a hazardous waste.

NESHAP targets the hazardous air pollutants associated with the paint spraying process. Hazardous air pollutants, as defined by the EPA, are substances known or suspected to cause cancer or other serious health effects, such as reproductive effects, birth defects, or adverse environmental effects. The type of equipment that can be used, the training needed to operate spray guns, where spray coatings can be applied, and maintenance of spray equipment are all regulated under NESHAP Subpart HHHHHH regulations. More information can be found in the additional resources section, including how to get an exemption.

P2 Opportunities

The painting process has many P2 opportunities available for all points of the process, from mixing paint to cleaning the spray equipment.

• Reduce overmixing by standardizing, checking, and improving the amount of paint mixed for a given vehicle type. Standardize a baseline for the amount of paint to be mixed for types of vehicles. Check and improve these amounts as time goes on and services are completed. This will allow you to measure the amount of mixed paint needed to minimize any excess paint that will no longer be used.
• Spray operator training to ensure proper application of paint. Staff training should always result in better service outcomes, reduce the need for repainting, and limit the generation of paint waste.
• Use Waterborne Paints. Water-based paints contain much less VOCs than other paints, providing better working conditions and a healthier environment. Do note that switching to water-based paints from solvent-based paints may require additional training and booth modifications to account for drying and application differences.
• Maintain your equipment. The only way to ensure your equipment functions correctly is to maintain it per the manufacturer's specifications. This extends to the spray gun and the compressed air system that may be used. Routine maintenance extends the life of your equipment and ensures they are working as efficiently as possible.
• Use high-volume, low-pressure (HVLP) spray guns or similar technology. Increasing paint volume and lower pressure significantly reduce overspray and paint use through greater transfer efficiency. This means more paint gets to where you want it to go. This equipment is required under NESHAP Subpart HHHHHH unless an exemption is approved.
• First, physical techniques are used to clean equipment after painting. This can be done by scraping leftover paint waste out of mixing cups and anywhere that can be reached. Additional solvent or water should be used sparingly. The resulting mix of the rinse liquid and paint waste adds significant amounts of hazardous waste to be managed or disposed of. 
• Upgrade to plural component sprayers that mix paint or coating components within the spray gun itself. This also allows for precise control of the ratios between components and can save staff time mixing paintings/coatings.

 In the next lesson, we will talk about other solid wastes.