The young women are sex workers and Omwenga "rents" them the alley for a few minutes at a time as a cheaper alternative than paying for hotel rooms. At the end of the evening, the women either pay him a cut of their earnings or, more frequently, offer him sex.
"Initially, all we wanted was to offer the corridors [alleys] for some fee, but standing around watching people making love makes us boil," he told IRIN/PlusNews. "As such, some of us came up with the give-and-take agreement with the girls."
Several Mombasa watchmen, or askaris, said the women also used the alleys to hide from police. "One sex worker promised to do anything for me if I hid her in the corridors from policemen conducting a raid one day," said Wallace Wanyama*.
He said he had had sex with at least five sex workers who used the alley next to the building he guards, but did not use condoms and had never been tested for HIV.
Sex work is widespread in Mombasa which has high levels of poverty and illiteracy and large numbers of international tourists, truckers and sailors. HIV prevalence is about seven percent, slightly lower than the national prevalence of 7.4 percent.
Condom use is erratic among the sex workers. Anne Jambi*, patrolling Mombasa's Moi Avenue, told IRIN/PlusNews that she always used condoms when she had sex with askaris, but Sue Pekeshe* said she could not remember whether she had used a condom during a recent encounter with a watchman because she was drunk at the time.
A 2007 study found that female sex workers in Mombasa who were binge drinkers were more likely to have unprotected sex, experience sexual violence, and contract sexually transmitted infections than those who did not drink.
Chewing khat - a widely used but addictive herbal stimulant - is common among watchmen trying to stay awake through the night, but has also been shown to increase risky behaviour.
Hard to reach
The odd hours that askaris work have made it difficult to reach them with HIV services. "Most of these guards are not easily accessible because of the demanding nature of their jobs," said Dr Esther Gitambo, the provincial director of medical services. "Due to the poor package they earn from their guarding jobs, most of them opt to work on other casual jobs during the day."
The risk of being mugged at night while trying to provide services to the watchmen was another complication said Rosemary Kenga, an administrator and counsellor at the AIDS Population and Health Integrated Assistance Programme (APHIA II), funded by USAID.
The APHIA II project provides "moonlight" voluntary counselling and HIV testing services to watchmen, sex workers and minibus-taxi operators during evening hours, but project coordinator Filberts Oluoch said the watchmen had been slow to make use of it.
"Watchmen are the most complicated to deal with," he said. "Some say their company policies don't allow them to speak to strangers, especially when they are on duty, a good example being those watching over huge business premises like banks."
APHIA II is now working with companies that employ watchmen to introduce workplace programmes that encourage behaviour change, such as condom distribution and workshops on preventing HIV.
"We often hold workshops and brief in-house meetings to enlighten our staff on the importance of self discipline when they are at their workplace," said Carlos Kioko, the communications manager of a large security company, Group4 Security. "We also supply them with free condoms."
jk/kr/ks/he
*Not their real names
This article was produced by IRIN News while it was part of the United Nations Office for the Coordination of Humanitarian Affairs. Please send queries on copyright or liability to the UN. For more information: https://shop.un.org/rights-permissions