Atmospheric pollution scatters and absorbs some UV light in the upper atmosphere and stops it reaching the ground. While reducing pollution is a net good, one unfortunate consequence of controlling and reducing the pollution that gets up to the upper atmosphere is that it will lead to a few percent increase in the UV dose people receive in the northern hemisphere. Skin cancer is associated with UV exposure so incidence of skin cancers will go up if sun safety is not observed.
Oh it's far more than that. Giant volcanic eruptions have been responsible for non negligible reductions in global temperatures due to reducing the sunlight which hits earth via scattering and other effects due to the pollution.
They probably didn't mean to a large degree, but air pollution does scatter light and UV radiation. As well as cause breathing problems, asthma, probably lung cancer, etc.
