Members of the environmental group Communities Against Gatwick Noise and Emissions - CAGNE - say the proposals are ‘simply unmanageable.’
They say there would be extra road traffic problems, more carbon pollution and extra noise for people living in the area.
Gatwick officials say that the expansion would create 20,000 extra jobs, but CAGNE maintains there is insufficient infrastructure to cope.
A spokesman said: “What we need is sustainability and not over 20,000 extra workers descending on our area looking for schools, affordable housing, health care and amenities which local authorities are struggling to accommodate currently.”
CAGNE spoke out after Gatwick Airport officials announced on Friday that they had instigated a formal application to bring the emergency runway into regular use.