Most interior painting these days uses low-VOC or zero-VOC paints. Clients sometimes ask which one is "safer" — the honest answer is: both are, and the difference is smaller than the marketing suggests.
What a VOC is
Volatile Organic Compounds are chemicals that evaporate off wet paint as it cures. They're what you smell in a just-painted room. The EPA limit for interior paint is 250 g/L.
Low-VOC
Typically 50 g/L or less. Many modern premium interior paints qualify — the product data sheet lists the exact figure.
Zero-VOC
Typically 5 g/L or less. Some lines stay zero-VOC after tinting — Benjamin Moore's data sheet lists Regal Select Matte at 0 g/L in any color. With other lines, colorant can add a small amount, so check the data sheet for the tinted figure.
When to specify zero-VOC
Nurseries, new-baby rooms, homes with asthma or chemical sensitivity, painting during winter when windows stay closed. Also preferred anywhere a pet can't be evacuated for a day or two.
When low-VOC is fine
Everywhere else. The odor is mild, the film is hard, the coverage is the same. Specifying zero-VOC universally can push you into less-good formulations just to chase the label. We default to low-VOC paints across all our interior painting projects, with zero-VOC available on request.