No specific recommendation, because it would depend on the type of gnat present. Most gnats do not bite, but if they are biting gnats that you're having problems with, using personal repellent is the most practical approach. Like all flies, gnats require moist substrate in which to breed, and while some gnats don't necessarily require standing water the way mosquitoes do, reducing issues with drainage or puddling water can help minimize outbreaks by denying them the habitat they need. You can look for sources of damp conditions and organic matter, such as partially-clogged roof gutters, areas of soil that remains soggy for long periods after rain or irrigation (consider using a rain garden, if feasible, to shunt that water into instead for faster drainage), or hose leaks. How far a gnat will fly from the area in which it lived as a larva is species-dependent, so if conditions for gnat breeding don't occur in your yard, they may be elsewhere in the neighborhood. As with mosquitoes, control of such insects isn't often as successful if one yard reduces its breeding sites compared to a whole street or most of the neighborhood doing so.

One approach we do not recommend is using pesticides. As with mosquitoes, any aerial spray targeting the adults will be short-lived and/or will harm other insects, including pollinators, because such chemicals are not specific to flies. While more fly-specific options exist for applications to water, the location to treat would have to be identified first, and in that case, it may be more practical and cost-effective to just reduce its moisture content instead of relying on multiple treatments per year to suppress fly breeding. (For private property; not much can be done about natural areas or nearby park land.)

Miri