While Louisville struggles to come into compliance with current Environmental Protection Agency standards for smog, the U.S. agency is proposing even stricter standards. Smog, or ground level ozone, forms when vehicle and other emissions react in sunlight. It can aggravate lung problems and has been linked to premature deaths. Metro Air Pollution Control District spokesman Matt Stull says attaining an “in compliance” rating from the EPA on the new standard will take time.“In the release from the EPA they say that attainment could be based and probably will be based on some technologies that aren’t even developed yet. So, you know, we’re hopeful that those come out and will help us to reach whatever number is proposed.”The EPA is holding public meetings on the proposed new standards in early February.