IT WON'T COMFORT those who have been brutalized in the past months, nor should it be read as an invitation for carefree travel through this city, but the latest crime news from the police is encouraging. Officials report that serious crime in the District declined in July for the ninth straight month. If this trend continues through the rest of 1985, they say, the city will have had the lowest crime level in 19 years. Without reading too much into these statistics, there is a message here not only for residents but also for people around the country (or even in the nearby suburbs) who may have exaggerated notions of what life in this city is like.

In this particular roundup, officials are talking about Part I crimes -- the police designation for serious offenses such as homicide, arson, robbery and burglary. There were 4,420 such reports for July -- a 4 percent decrease from July '84. For the first seven months of this year, serious crimes were 9 percent lower than for the first seven months of '84. That's still a lot of unpleasant action every day, and at the present rate projects to about 4,800 serious crimes for all of 1985.

But Police Chief Maurice T. Turner Jr. is pleased and has some explanations for the improved numbers. Not surprisingly, he gives credit to "exemplary" police officers -- and why not? In addition, the chief cites local programs such as Neighborhood Watch, Operation Identification and the Crime Solvers program -- each involving resident participation -- as having led to the arrests of more than 350 suspects this year. Other factors cited are the Repeat Offenders Project, which tracks recidivists suspected of committing multiple crimes, and the police narcotics task force.

Perceptions -- fears and doubts -- may take longer to change. But if the police are doing a good job, it is made better by citizen cooperation. In turn, the degree of that cooperation hinges on the professionalism and sensitivity of the police. That partnership does seem to be working relatively well these days -- a fact worth celebrating.