For numerous reasons, Legionella is a new and growing epidemic, with the number of high-profile, deadly events increasing each year. With proper monitoring and maintenance of equipment, this can be avoided, protecting the health of both the workers and those the industry serves.

By Diana Hulboy, Ph.D.

In September 2014, a street cleaning truck in Ripollet, Spain, was responsible for an outbreak of Legionnaires’ disease that resulted in 10 deaths throughout the region, through the aerosolization of Legionella-contaminated water by the truck’s brushes ( Although this may sound like a unique and isolated incident, the spread of this disease, and others, through such unusual means is becoming increasingly more common. The potential risk for the waste industry is high and it may be only a matter of time before it too is involved in such an incident. Efforts are being made in the U.S. to provide guidance on Legionella monitoring and management by entities including the American Society of Heating, Refrigerating and Air-Conditioning Engineers, and the American Hotel and Lodging Association, among others. Although U.S. governmental agencies have not yet issued requirements, they are aware of the potential health risks. The U.S. EPA (Environmental Protection Agency) is currently considering adding it to its list of contaminants of concern, and OSHA and CDC have ample information and recommendations on their Web sites. The U.S. will likely follow the European Union, which the World Health Organization (WHO) has noted is making progress in governmental Legionella regulations.

The first known outbreak of Legionnaires’ disease (Legionellosis) occurred in 1976 at the American Legion Convention in Philadelphia. Several hundred people were sickened, and 34 died. Local authorities worked with the CDC to culture and identify the bacteria. Since then, worldwide outbreaks of Legionnaires’ disease have induced organizations and health authorities to implement guidelines for bacterial monitoring and disinfection, as well as diagnosing and reporting the disease. There are more than 40 species of Legionella, nearly half of which are known to cause disease. The species Legionella pneumophila is responsible for most of, but not all, outbreaks. The growth requirements for Legionella occur in most water systems today:

  • Temperature above 68° F
  • Iron and L-Cysteine
  • Biofilm

In addition, Legionella can survive at lower levels of dissolved oxygen than many bacteria, and are partially resistant to chlorine. Typical plastics and organics found in our water systems provide additional growth-enhancing nutrients (Source: EPA, “Legionella: Human Health Criteria Document” EPA-822-R-99-001, 1999; and “Draft – Technologies for Legionella Control: Scientific Literature Review” EPA 815-D-15-001, 2015).


Vehicles Spreading the Bacteria

The street cleaning truck incident that occurred in September 2014 was not the first Legionnaires’ outbreak in Spain linked to an unusual source. A similar scenario had occurred in Alcoi, Spain, when an increase in cases of Legionellosis culminated in an epidemic outbreak in 2009. Analysis eventually identified the source as the water tank in a milling machine used for street asphalt paving. The machine was removed from service and disinfected, ending the epidemic.

Such incidents illustrate the fact that something not normally considered to be a risk can cause Legionnaires’ disease outbreaks. According to Coscolla et al., who wrote about the Alcoi incident (, “These kinds of machines are good candidates for spreading L. pneumophila infections, given their ability to generate aerosols. These machines are used in urban areas where contaminated aerosols can be inhaled by many citizens. They are continually moving, making their identification as a source of infection more difficult because by the time an outbreak is detected and the causative L. pneumophila strains are characterized, these machines have usually moved to another location. Lack of suitable cleaning routines for these machines makes them excellent candidates for colonization with L. pneumophila. In this particular outbreak, use of untreated water from a natural spring contributed to the contamination of the tank and milling machine. These devices are frequently stored and operated in and from industrial areas where non-treated water supplies are common, which increases risk for colonization by L. pneumophila. Whether they spread L. pneumophila more easily than other devices usually linked to such outbreaks, like cooling towers or spas, is unknown, but they should be considered risk devices for the reasons detailed above.” This same reasoning would apply to street cleaning trucks, and, by extension, the waste management industry.


A Growing Problem

Industrial water systems provide ideal conditions for the growth of Legionella bacteria, including temperatures above 68° F and the presence of iron. It is spread through the air via fine water droplets (aerosols) that can be produced by various processes, including misters, condensers, showers or scrubbers (Source: Occupational Safety & Health Administration Potential sources of Legionella in the waste and recycling industry can include:

  • Wet cooling systems (for example, cooling towers and evaporative condensers)
  • Hot and cold water systems (for example, showers, eye washes and taps)
  • Machine cooling systems (for example, in lathes and plastic injection machines)
  • Spray booth water curtains
  • Humidifiers in food cabinets and factories
  • Dust suppression systems
  • Fire suppression systems
  • Vehicle washes and power hoses

An estimated 56,000 to 113,000 people are infected with Legionella bacteria in the U.S. each year. There is no vaccine for Legionella-related diseases. Once inhaled, Legionella bacteria can cause Pontiac Fever, a flu-like illness that afflicts approximately 90 percent of exposed individuals, or the more deadly Legionnaires’ disease (pneumonia). Although Legionnaires’ disease occurs in only a limited percentage of people who are exposed, between 8,000 and 18,000 people are hospitalized in the U.S. each year, the fatality rate is 28 percent (Centers for Disease Control and Prevention

In a 2015 report, the CDC reported an alarming increase in Legionella-related disease outbreaks in the U.S. One such outbreak gained national attention last summer when 12 people died and over 100 more were infected from Legionella spread by a cooling tower on the Opera House Hotel in South Bronx. After a lengthy disinfection process, the outbreak ended, and New York State later released a regulation requiring all cooling towers be monitored regularly and treated when necessary. Flint, MI, already hit by high lead levels in its drinking water, saw a 6- to 14-fold increase in Legionnaires’ disease cases in 2015 compared to the four preceding years.

A combination of aging population, better diagnostics, increased awareness, environmental factors and infrastructure changes are thought to be responsible for the increase in outbreaks.


Preventing the Spread of Legionella and Similar Diseases

In the incident involving the asphalt paver, Coscolla et al. ( reported that “the milling machine and the water tank were immediately confined outside the city, sealed, cleaned and disinfected … [and] a new cleaning and maintenance protocol was implemented to prevent future contamination. The cleaning protocol consisted of treatment with chlorine (20 ppm) and removal of the atomizers and their replacement by gravity-based water distributors. Additionally, for operation in the city, use of a separate thermo-insulated water tank in which chlorine was continuously applied at 20 ppm was required, thus preventing any further growth of L. pneumophila. Additionally, water had to be obtained from the municipal system.” Similar measures can be taken by the waste and recycling industry.

There are many tools available to help inform your employees of the potential of a Legionella outbreak, and give guidance on monitoring and prevention:

  • ANSI/ASHRAE Standard 188-2015, Legionellosis: Risk Management for Building Water Systems—Provides guidance for establishing a Water Management Program.–publications/bookstore/ansi-ashrae-standard-188-2015-legionellosis-risk-management-for-building-water-systems Although the methods described here are not required by any agency or government, they are recommended by certain entities such as New York State, which passed a regulation for cooling towers after the deadly outbreak last year.
  • U.S. Occupational Health and Safety & Health Administration (OSHA)—The OSHA Technical Manual includes a chapter (Section III, Chapter 7) on Legionella
  • U.S. Centers for Disease Control and Prevention (CDC)—Has a Legionella information section on its Web site
  • American Industrial Hygiene Association (AIHA)—Released a new guideline on the recognition, evaluation, and control of Legionella colonization and amplification in common building water systems

In addition, there are many companies throughout the U.S. providing monitoring, maintenance and disinfection programs for Legionella. Your employees can also perform Legionella testing as part of an in-house monitoring program. When selecting Legionella testing and monitoring kits, be sure to evaluate whether they:

  • Provide rapid results (1 hour)
  • Detect most Legionella species, not just L. pneumophila
  • Are sensitive (100 cfu/L or less)
  • Are capable of either visual or optical detection
  • Are quantitative
  • Can also detect VBNC (Viable But Not Culturable) Legionella and biocide-treated samples
  • Are easy to multiplex with other water test analyses
  • Give few false negatives
  • Give few false positives
  • Are AOAC (Association of Analytical Communities) Certified


The AOAC is an internationally-recognized and respected organization that develops “science-based solutions through the development of microbiological and chemical standards. AOAC standards are used globally to promote trade and to facilitate public health and safety.”


Addressing the Risk

For numerous reasons, Legionella is a new and growing epidemic, with the number of high-profile, deadly events increasing each year. The waste and recycling industry is in a vulnerable position, with the potential to be responsible for causing outbreaks of this disease, endangering employees and the public. With proper monitoring and maintenance of equipment, however, this can be avoided, protecting the health of both the workers and those the industry serves. | WA

Diana Hulboy is Strategic Leader, Operations and Business Development for Abraxis LLC, headquartered near Philadelphia, PA. She has a Ph.D. in Biomedical Sciences and has worked in the testing kits industry for 15 years, throughout that time playing a variety of roles including R&D, product management, marketing, and technical sales. She is grateful to L. Kamp for her editorial review of this article. Diana can be reached at (215) 357-3911 or via e-mail at [email protected]