The GDPR outlines an additional category of personal data which requires some additional considerations. This is the special categories of personal data. When working with special categories of personal data there are stricter conditions:
Racial or ethnic origin
Political opinions
Religion or philosophical beliefs
Trade union membership
Health
Including any type of physical measurement, assessment of mental well-being or cognitive function, even in a non-clinical population
Sex life or sexual orientation
Personal data concerning criminal convictions and personal data concerning unlawful or objectionable conduct for which a ban has been imposed
Biometric data (fingerprints, iris-scans)
Genetic data
Contact your Privacy Champion if you think this applies to your research.