In many major Chinese cities you literally cannot see the sun bc of air pollution. No major city in VN is this bad. Will it get worse? Maybe but I wouldn't necessarily expect it. VN people actually do get quite concerned about the quality of their food and, if air pollution started to become a visible problem, in places like HCMC, I doubt people (govt officials included) would be OK with that. The drive for money is hard but not quite as no-holds-barred as PRC.