MARYLAND — For more than a month, governors in a vast majority of states have urged people to stay indoors and away from one another, critical measures needed to slow the spread of the coronavirus.

But as the lockdowns drag on, the weather gets warmer and some states move to reopen, researchers at the University of Maryland have found that more people across the country are going outside, that they are doing so more frequently and that they are traveling longer distances.

The changes in behaviour, tracked using cellphone location data, have been measured in the past two weeks and can be seen in all but three states.

Starting in mid-March, when most stay-at-home orders were announced, fewer people went out and people also made less frequent trips, according to the research. For weeks, the numbers held steady.

Then, starting April 14, the data showed people increasingly going out, a trend that continued through Friday, said Dr Lei Zhang, director of the Maryland Transportation Institute at the University of Maryland, College Park, which is leading the research.

In Texas, for example, 25 per cent of people stayed home on April 24, the most recent day for which data was available, compared with 29 per cent on April 10, two weeks earlier. In Ohio, people took 3.2 trips, on average, on April 24, up from an average of 2.8 trips two weeks before. In Louisiana, people traveled an average of 31.1 miles, up from 24.7.

The research suggests that people are growing increasingly restless, Dr Zhang said. It also suggests people are increasing the chances that they will interact with others and possibly spread the virus.

Dr Zhang called the phenomenon “quarantine fatigue.”

“It just seems that people are getting a little tired collectively of staying at home after we passed that one-month mark,” he said.

The phenomenon appeared to be on display this past weekend, as throngs of people packed beaches in Southern California on a hot Saturday despite pleas from public officials to consider staying indoors. In New York on Saturday, warmer, sunnier weather drew crowds to the city’s parks.

Dr Zhang said it was theoretically possible that people were going outside more while still maintaining the recommended 6 feet of distance from others and taking other precautions, such as wearing masks and gloves.

But he cited news reports about people congregating at beaches and in parks as evidence that social distancing was not always happening.

It becomes harder to follow social-distancing guidelines, he said, “when people go out more and go to more places and stay there longer”.

The findings may be particularly troubling in the United States, the country hardest hit by the coronavirus pandemic.

Experts have cautioned that there will be no imminent return to normalcy and that a return to communal life will most likely come in stages. Without adherence to social distancing, the virus could surge anew, experts have warned.

A few states have moved in recent days to gradually reopen parts of their economies, but most Americans are still being urged to stay home.

The research also seems to run counter to polls, which suggest that a majority of Americans support the restrictions that governors and local officials have imposed.

“I think people feel the obligation to do it even though they are not doing it as much as they are reporting they are,” Dr Zhang said.

There also appear to be signs of small changes in attitude among some Americans toward social-distancing measures, according to some polls.

According to a Gallup poll conducted the week of April 13, 62 per cent of adults surveyed said it was very likely that they would stay home for a month if public health officials recommended doing so based on an outbreak in their community. That number was down from a high of 67 per cent in the week of March 30.

Similarly, a Gallup poll conducted the week of April 20 found that 59 per cent of respondents said they had practiced social distancing in the previous 24 hours. That was down from 65 per cent in the week of April 6.

The Maryland Transportation Institute’s research is based on anonymised cellphone location data that is updated daily. A trip is counted if the end point is more than a mile from the person’s home and he or she stays there for more than 10 minutes, Dr Zhang said.

That way, the research does not pick up people who are just checking the mail, going for a jog or walking the dog.

Researchers created a measure that they call a “social-distancing index” by combining a number of other metrics using the cellphone data: The percentage of people in a state or county who are staying home, the number of trips per person per day, the distance of those trips and the number of trips taken beyond county or state borders.

“Overall, we try to measure the opportunity that people can interact with each other and give more chances for viruses to be passed on from one to another,” Dr Zhang said.

He said researchers recorded recent increases in the number, frequency or distance of people’s trips outside the home in every state except Massachusetts, Rhode Island and Wyoming. Louisiana, Ohio, Texas and Vermont were among the states where the largest increases were measured, he said.

The research, Dr Zhang said, suggests that state and local governments need to improve their messaging about their stay-at-home orders.

“The moment people start seeing the curves flattening, the number of cases start dropping or holding steady,” he said, “that gives people a false sense of safety.” THE NEW YORK TIMES