In the past, they often went unnoticed, but now janitors, housekeepers and cleaning crews are front and center as the experts in cleaning and disinfecting amid the coronavirus pandemic.

A survey of top firms turned up recommendations to help people reduce the threat of coronavirus making it into their homes, cars, offices and other spaces.

That’s a huge need, said Kevin Behan, spokesman for AdvantaClean. COVID-19 can stay viable for hours to days on paper, metal and other surfaces and can be picked up on a trip to the grocery, pharmacy, gas station or any other place.

Following are some of the disinfecting tips shared by Mr. Behan and others.

Bleach or 70 percent isopropyl alcohol are the best at killing germs, including the coronavirus. For bleach, a little bit goes a long way. Dilute using one-third cup bleach, or five tablespoons, per gallon of water, or four teaspoons per quart. When wiping, keep surfaces wet for several minutes to ensure germs are killed.

Alcohol also is highly effective, the U.S. Centers for Disease Control and Prevention and cleaning firms note. Isopropyl alcohol is recommended for use because it has a higher alcohol content than drinking liquor. Experts advise diluting 90 percent or higher isopropyl alcohol with one-third distilled water to get the best germ-killing results.

Regularly disinfect potential hot spots, such as door knobs, desks, phones, computer mice, files, tables and other places that are used or touched regularly by one or more people.

Alcohol is recommended for disinfecting keypads, screens and exterior portions of computers and cell phones, which often are overlooked as needing disinfectant. Experts urge care to avoid getting wet disinfectant inside the equipment.

Apply disinfectant in one direction. Rubbing back and forth or in a circular motion can redeposit germs.

Use a color-coded system of cleaning cloths, with one color for the kitchen, one for the bathroom, one for a home office, etc. That can keep you from using the same cloth to clean different areas and reduce the potential for spreading germs from one area to another.