CLEAN ON PAPER, DIRTY ON THE ROAD - TROUBLES WITH CALIFORNIA SMOG CHECK

Smog check programmes have failed. Official studies in the US show red uctions in emissions of only about half those predicted when the progr ammes were adopted. Other studies show no effect at all. The failure a rises for several reasons: (1) Current programmes only encourage cars to be clean on one day every two years - the inspection day; (2) Curre nt programmes do little to deter motorists from tampering; (3) Althoug h most emissions come from a few vehicles with high emissions, current programmes require inspection of all cars; (4) Garages often do not r epair cars properly; indeed, about half the cars repaired following an inspection have increased emissions.