Here in LA, we love to gripe about how bad the smog is. It's a national cliché. But if you're old enough to have taken a deep breath in Los Angeles back in the 1970's, you know just how bad air quality can get. Thanks to passing the strictest emissions regulations in the country, California now has relatively decent air. So, at least to environmentalists, rolling back tough regulations for diesel trucks -- the worst air pollution offenders left in the state -- seems to set a bad precedent. But truckers say they need more time to retrofit their rigs and to update to cleaner models. In response the California Air Resources Board has proposed relaxing rules for aging diesel rigs… They're expected to decide this on Thursday.