Eco-friendly paint, or natural paint, is paint that has been specially designed to have lower levels of volatile organic chemicals (VOCs, for short).
VOCs are responsible for that familiar fresh paint odour of a conventional paint consists of a variety of greenhouse gases and other environmentally harmful chemicals that are released to the atmosphere as the paint is applied. VOCs are the main reason painting instructions advise that you only work in well-ventilated areas.
The pigments used to create the colours can also be hazardous at certain levels since many are made from heavy metals.
Conventional Paint and VOCs
When you open a can of conventional paint what you'll see is a creamy blend of plasticisers, adhesives, hardeners, pigments, biocides, drying accelerators, solvents and more. The solvents used in conventional paints are Volatile Organic Compounds. VOCs help hold the ingredients in a blended state while the paint is liquid, but they escape to the air when the paint is applied. Outdoors, VOCs combine with other airborne pollutants to create smog.
Indoors, VOCs and plasticisers contribute to unhealthy indoor air, and extended exposure to these hazardous air pollutants (HAPs) can lead to respiratory and metabolic illness, headaches and a host of other disorders. In some instances conventional paints may continue emitting trace portions of VOCs, biocides and plasticisers for more than a year after application.
Regulations allow interior water-based house paints, for instance, to contain up to a certain amount of VOCs per litre of paint. This varies from country to country and there are paints that are free of VOCs altogether. Paint companies often tout these products as an environmentally friendly option, but the eco-reality is a bit more complicated.
These products may still contain HAPs, and adding colourants to some low-VOC paints can increase the VOC measurement as well.
Certified Green Paint
While paints with reduced levels of VOCs are more eco-friendly than conventional paints, some house paints have an even lower environmental impact. Homeowners can select premium-grade zero-VOC paints that also use VOC-free colourants, are free of vinyl and other plasticisers and include no toxic biocides. Independent organizations test paints to ensure that they meet the highest standards of eco-friendly performance.
Casein paints are made primarily from milk proteins, lime, and non-toxic pigments. This may be the most eco-friendly paint available, but it's not without some practical drawbacks: the paint is not nearly as durable as modern coatings and colour choices are limited. Casein paints are usually supplied in powder form and should be mixed with water immediately before application.
[Information sourced: https://homeguides.sfgate.com/]