I think my husband and I may have conceived a week ago. Yesterday I was standing next to a barbecue grill for about an hour talking with friends. Now I have a pretty bad cough. I don't know what kind of grill it was... I'm wondering if toxic fumes may have been harmful at this stage of pregnancy and if one hour is a risk?

Nothing to worry about.
If that where the case you'd never go outside the house at all and even then you'd be in danger..

Your bronchial tubes and lungs are miracles of filtration and other defenses like cilia moving particulates back up and producing mucous. As long as you didn't faint from carbon monoxide, don't worry about this cough, which is your body getting rid of particulates in the smoke.

You would have to stand there every day for months (or smoke cigarettes, or be a traffic cop in the middle of a busy street) to start filling up the alveoli (little sacs) of your lungs with so much carbon dioxide and particulates that oxygen couldn't get into your bloodstream.

Charcoal grills do produce more CO2, CO, and particulates than gas grills. But it certainly makes sense for anyone, pregnant or not, to try to avoid standing around either of the types.

No issues at all.