Mandatory thresholds on…

Mandatory thresholds on carbon emissions or other chemical contamination. Financial penalties that are substantial enough to hurt if companies do not comply.

Reduced property tax as a financial incentive for companies that meet exceptional standards in low emissions.

Companies have more financial ability to change than citizens. For example, I cannot afford a more fuel efficient vehicle, but companies can create more affordable efficient vehicles. Government regulation can force companies to sell low-emissions vehicles.

Financial incentives to companies who change their transportation fleet to low-emission or electric vehicles (lower tax? a certification system that alerts consumers about clean companies?)