After years of court battles with environmental groups over those exemptions, the EPA is now proposing stricter limits on when petrochemical and other industrial plants can allow for emissions. “You have to consider the vulnerability of these communities," said John Sullivan, an environmental health researcher at UTMB. "We’re about to undergo a period of great expansion [of the petrochemical industry]." And while that's good for the economy, he said, "we have to think about the added burden of pollution that this is going to create."