Cwmfelinfach waste plant objections over 'trapped fumes'
People have objected to a planned waste processing plant because they are concerned about a weather phenomenon.
This is when cold air is trapped in the valley by the warm air above and there are fears emissions may also be caught.
A report for Hazrem Environmental said the site would have a "negligible" impact on air quality.
The plant would be built on the Nine Mile Point Industrial Estate and would turn household, commercial and industrial waste, which may normally go to landfill, into bales of fuel.
Temperature inversion means clouds and fog can sometimes take days to disperse and people living nearby are worried that would be the same for emissions from the site, as well as fumes from vehicles coming and going.
A planning document said an environmental impact assessment "is not required for the proposed development".
A Caerphilly council spokesman said: "As with all planning applications, residents' views, comments and objections will be considered by the council as part of the planning process".
Resident Allan Sharp said: "If I were looking for a place to build a factory of this nature, this would be about the last place on earth I would choose, look around you, it's just a deep groove in the ground."
Councillor Jan Jones, a member of a group opposed to the development, said: "There's a lot of concern in the valley, we've had over 1,500 named petitions submitted and basically people have just had enough".
A decision on the plans will be made at a meeting of the council's planning committee on Wednesday.