Help on strange smell please!

[mypinkmonkey]

For last couple of weeks we have had a strange smell in the house - starts at about 9am and lasts for a couple of hours and then it's gone. It's hard to describe - bit like a pesticide sort of smell. I thought it may be from the local farm spraying something but it doesnt fill the whole house just the hallway and kitchen area and I can't smell it outside. Any ideas on how I can trace the source please. There is no definitive spot from which it seems to emanate. It is starting to drive me nuts! TIA

might be someone starting a car outside in the morning. Before the catalytic converter hears up, the exhaust smells.

It's not a fishy smell, is it?

Does it happen after the bath or shower has been used; or after the boiler first fires up after being off overnight? If the boiler is nearby, sniff the flue and the pipe that comes through the wall, and any drips underneath; and, if you can see it, the boiler condensate pipe which is probably white plastic.

Before we had our house rewired the light switches used to smell strange.
We also has old light fittings which stunk. Couldn't work out where it was coming from for weeks.
Give the lights a sniff to see if it could be them. Smell your light switches too.

i wouldn't describe it as pesticide, but it was nasty and a chemical.

Pipes. Maybe someone in the area uses the waste pipe such that it gets a back log at that time.

We had a strange smell in our hallway a few years ago and it turned out to be the fusebox in the garage was burning slowly, we found out in time though. We have an internal door in hallway which goes through to the garage!

Thanks for all your replies. Aplogies for my silence - have had wifi issues!
PigletJohn- it is first thing in morning after boiler comes on and water has been used but the boiler is at other end of house and in in an outside cupboard and the smell is mainly in the hallway. Will have a sniff at it tomorrow!
Have found a tiny leak from a water pipe in the airing cupboard but smell doesn't seem to be coming from there.
WowOoo - I thought about the lights and have checked those and they seem ok.
Just so weird that it doesn't last all day.

Is the water leaking down? We had a horrid smell in our hall when we had a leaky shower in the bathroom, it was only when the hall had been closed up all night, when the rooms were aired, there wasn't a smell

where is the airing cupboard?

You have a hot water cylinder, then? Is there a smell near or underneath it? Can you see any brown spots on the ceiling, underneath where the pipes run between boiler and cylinder?