Researchers at the Massachusetts Institute of Technology (MIT) have developed a mathematical model that can help businesses determine the best way to reopen after a lockdown. The model takes into account a number of factors, including the number of employees, the size of the business, and the local infection rate.

The model can be used to simulate different scenarios and see how they would affect the risk of infection. This information can then be used to make decisions about things like how many employees should be allowed to work at the same time, how often the workplace should be cleaned, and whether or not employees should be required to wear masks.

The researchers say that their model could be a valuable tool for businesses as they navigate the challenges of reopening during the COVID-19 pandemic.

Here are some of the key findings from the study:

* The risk of infection is highest when the number of employees in the workplace is high, the size of the workplace is small, and the local infection rate is high.

* Requiring employees to wear masks can significantly reduce the risk of infection.

* Increasing the frequency of cleaning can also reduce the risk of infection.

* Businesses should consider implementing a phased reopening plan, in which they gradually increase the number of employees in the workplace over time.

The researchers say that their model is not perfect, but it can provide businesses with a starting point for making decisions about how to reopen. They also say that the model can be customized to fit the specific needs of a particular business.

The study is published in the journal _Nature Human Behaviour_.