The city Health Department’s reluctance to do responsible pesticide spraying puts New Yorkers at increased risk from West Nile virus.

As the city headed into the Labor Day weekend, six new West Nile cases were reported — bringing Gotham’s total to 14 (with one fatality) for 2012, up from 11 all last year and with more likely ahead. At least 30 New Yorkers have died from West Nile since it showed up in America.

Responsible use of pesticides is a proven way to reduce virus-carrying mosquitoes. Yet the Health Department caves to activists who claim that, even at low concentrations, the pesticide Anvil somehow puts us at unnecessary risk.

Because of their failure to use Anvil early and widely enough, Health Commissioner Thomas Farley and Mayor Bloomberg bear some responsibility for the predictable and partly preventable West Nile cases continuing to plague the city.

“The peak of West Nile virus epidemics usually occurs in mid-August, but it takes a couple of weeks for people to get sick, go to the doctor and get reported,” says Dr. Lyle Petersen, the director of CDC’s Vector-Borne Infectious Disease Division.

Yet the city now sprays only well after the virus has been found in neighborhood mosquitoes.

The department’s own 2011 environmental-impact study found the use of Anvil to control adult mosquito populations to be the safe choice — that the very low risk from exposure to small amounts of residual pesticides outweighs the serious risk of contracting West Nile. In other words, spraying is a no-brainer.

Yet, once it finds the virus in mosquitoes in a given neighborhood, the Health Department waits weeks before spraying. And it sprays only in the immediate areas where West Nile was found.

Officials shouldn’t be surprised when the virus, found in Staten Island mosquitoes on July 6, somehow managed to make it to other boroughs within days or weeks. It isn’t as if mosquitoes have to sit in traffic.

The department waited nearly two weeks, until July 19, to spray in Staten Island. It didn’t start in Brooklyn until Aug. 23, nearly a month after the first West Nile mosquitoes were found there.

And in Manhattan, the city didn’t spray until last week — nearly a month after the first virus-bearing bugs were found in the borough, and almost two months after the West Nile was found just a ferry-ride away.

This slow-to-spray policy thrills activists, but city residents bear the risk. This disregard for public health, rooted in unscientific fear of a pesticide, is scandalous.

While Bloomberg and Farley stay busy fighting salt, sugar and fat, they’re neglecting this most fundamental job of any city’s Health Department.

Plus, this p.r.-savvy team sparks needless fear of pesticides — building up public opposition to spraying in future years.

The Public Notice posters that plastered my Upper West Side neighborhood last week warned of all sorts of dangers from Anvil, suggested turning off fans and air conditioners and listed the phone number for the Poison Control Center.

But the scary signage contained nary a word about Anvil’s long and thorough safety record, nor anything on the dangers of West Nile.

It’s no wonder that some of my neighbors were terrified. Dog owners, unsettled by the one-sided leaflets, thought it best to keep their pups inside as late as possible on Friday, even hours after the spraying. That morning, when I took my black lab B.B. out for a walk, I also noticed an unusual absence of baby strollers — three hours after spraying ended.

Yet sumithrin, the pest-killing chemical in Anvil, is also approved for use directly on pets to kill fleas and ticks — and on kids, for head lice.

Farley should have launched his well-tuned media machine to actively explain why — as his own studies found — spraying is the safest thing to do, given the severity of West Nile and the high risk from the prevalence of the virus this year.

The Bloomberg administration hasn’t shied away from what it calls “cutting edge” approaches to public health. But it ought to get back to basics, and lead by telling New Yorkers that the EPA-approved pesticides it uses aren’t a cause for concern — disease-bearing mosquitoes are.

Jeff Stier, a National Center for Public Policy Research senior fellow, lives on the Upper West Side.