The phrase "activity has existed" is correct and usable in written English.
It can be used to indicate that a particular activity has been present or ongoing over a period of time.
Example: "The activity has existed in various forms for centuries, adapting to the needs of different cultures."
Alternatives: "activity has been present" or "activity has been ongoing".
Molecules designed for interfering with aromatase activity have existed for many years.
It is a little-known fact that this "work-related activity" initiative has existed for some years as part of New Labour's Pathways to Work scheme, so it isn't being rolled out to long-term unemployed because it's what the long-term unemployed already have to do.
This means that the General Tax on Polluting Activities, which has existed since 1999 for a limited number of activities such as waste storage and disposal, aircraft take-offs from airfields that are open to the public etc., would be extended to the road haulage industry.
The authors cite encounters with tuberculosis (TB), syphilis, HIV/AIDS, and immunization registry efforts to illustrate the pervasive tension in disease surveillance activities that has existed between privacy and the welfare of society since the inception of surveillance in the 19th century.
The LRA has existed for more than 25 years, eluding military efforts and negotiations seeking to put a stop to their activities.
Surrogacy has existed since antiquity.
On April 8, after widespread demonstrations, the King ended a 29-year ban on political activity that had existed under the partyless system of government introduced by his father, the late King Mahendra.
While some have been updated to reflect safety guidelines or science, others, like snowboarding, geocaching and paddle sports, have been brought in to cover new interests and activities that might not have existed a few decades ago.
"Female sports activity has not existed," said Prince Faisal, "and there is no move in this regard".
