The problem with BB cream sunscreens
Why should you avoid sunscreen products that only contain one active ingredient (titanium dioxide)? They don't offer protection against the full spectrum of UV light.

Lately I’ve noticed that some products advertise SPF protection, but only contain one active ingredient: titanium dioxide. Why is that a problem? Because titanium dioxide only protects against part of the UV spectrum—specifically, UVB and UVA2 rays. It does not protect your skin from UVA1 (340–400 nm) rays, according to this table from the Skin Cancer Foundation.