When smoke from wildfires is in the air, employers may wonder if the smoke is a health hazard and if they can do anything to protect their workers.
Smoke is a complex mixture of gases and fine particles. The fine particles in smoke are the primary health concern. Irritating chemicals in the smoke, such as formaldehyde and acrolein, are not present in levels to cause a public health concern, but they contribute to the irritating effects of the particulate matter. The level of carbon monoxide in the smoke is typically only a concern for firefighters close to the fire line.
Health effects depend upon the level of smoke and the sensitivity of the individual. They can include irritation of the eyes and respiratory tract, cough, phlegm, wheezing, difficulty in breathing, and chest discomfort. Exposure to smoke may also depress the lung’s ability to fight infection. People with asthma, lung disease, or heart disease are more likely to be affected by smoke, and their conditions can be aggravated by smoke. The risk of cancer or other long-term health effects from short-term exposure to smoke is considered to be quite low.
Employers should stay alert. They should listen to local news, weather forecasts, and air quality alerts. Air quality advisories and news can also be found at www.airnow.gov. Air quality districts rate the air as good, moderate, unhealthy for sensitive groups, unhealthy, very unhealthy, or hazardous. Depending upon the conditions, recommendations may be made that apply to sensitive groups or to everyone. These recommendations are geared towards the general public, so employers should be sure to use appropriate judgment when applying them to the workplace.
Staying indoors is a common advisory. This is useful if the air inside is cleaner than the air outside. The doors and windows should be kept shut. The heating, ventilation, and air-conditioning (HVAC) system should be set to maximize the amount of recirculated air and minimize any fresh air being brought in. The HVAC system should be fitted with a filter that is as efficient as possible without adding too much resistance for the system to operate properly. Filters may also need to be changed more frequently because of wildfires. Some buildings are so “leaky” that the air inside is as bad as that outside. If the air inside is unhealthy, it may be appropriate for some or all employees to remain at home or at some alternate location.
Portable room air cleaners can supplement the filtering of particulates done by an HVAC system. The effectiveness of an air cleaning device is a function of the cleaning efficiency, the air exchange rate, and the room size. Portable room air cleaners may not be effective for large office buildings, or places with large open areas. Some air cleaners are mechanical: the air is pulled through a filter that traps particles. Other air cleaners are electronic; these include electrostatic precipitators (which use an electrical charge to collect particles pulled through the device) and ionizers (which cause particles to stick to materials, such as walls and carpets, near the ionizer). These electronic devices produce some amount of ozone (a respiratory irritant) as a result of the ion-generating technology used. Some “air purifiers” or ozone generators are specifically designed to generate ozone and should not be used. The Cal/EPA Air Resources Board has more information on air cleaners at http://www.arb.ca.gov/research/indoor/acdsumm.pdf.
Heat stress may become a health issue in some buildings during warm weather. Buildings without air conditioning may rely on open windows or doors to keep indoor temperatures from becoming too hot. In some smoke conditions, however, opening windows may not be acceptable. If exposure to heat stress or smoke are the only options, it may be appropriate for some or all employees to remain at home or at some alternate location.
Air contaminants generated within the workplace can be a concern. Open doors and windows may provide the outside air needed to control exposures to air contaminants from forklifts, welding, or other operations. Even local exhaust ventilation relies on make-up air from the outside to control exposures. It may be appropriate to limit or even stop some operations so that employees are not exposed to smoke and industrial air contaminants at the same time.
Reducing physical activity is also recommended when air quality is unhealthy. With increased physical activity, breathing rate increases and so does the amount of pollutants inhaled. With heavy exertion, workers also tend to breathe more deeply, depositing particles more deeply into the lungs. Heavy exertion may also cause workers to breathe through their mouths, bypassing the filtering mechanisms of the nose. Employers should review the level of physical exertion needed for all operations and limit or stop some activities if appropriate.
In general, the use of masks is not recommended for widespread use in areas affected by smoke. However, their use may be appropriate in some limited situations, such as some workers who need to be outdoors. In order to provide any protection, a mask must be able to filter out the microscopic particles in smoke and it must provide an airtight seal against the face. Surgical-type masks and “comfort” masks sold at the hardware store do not protect the wearer from smoke.
Masks specifically designed to protect workers from air contaminants are classified as respirators and are certified by the National Institute for Occupational Safety and Health (NIOSH). There are disposable respirators or “dust masks” available which are certified by NIOSH to filter out microscopic particles. These are marked as N, R, or P and 95, 99 or 100 (e.g., N95 or P100). There are many workplaces that use these masks on a routine basis. However, these respirators can be difficult to breathe through, leading to increased breathing and heart rates; they can also contribute to heat stress. Therefore, those groups that are more sensitive to smoke may also be more likely to have adverse health effects from using a respirator. When an employee’s job requires an employee to wear a respirator, the employer must develop and implement a written respiratory protection program. This program includes medical evaluations, fit-testing, and training along with other requirements. Employees that are not required to use respirators but are considering using them for protection against smoke should consult their physician first if they have cardiac or respiratory disease. Cal/OSHA has more information on respirators in the workplace at www.dir.ca.gov/dosh.
Consider the commute. Even if the air where the workplace is located is relatively unaffected by wildfires, employees may need to travel on roads with unhealthy levels of smoke or where reduced visibility makes driving dangerous. Employers should also be on the alert for road closures and notify employees if their commute home is affected.
Encourage workers to report any health effects. If workers experience symptoms such as chest pain, chest tightness, shortness of breath, or severe fatigue, medical attention should be sought.
After a fire, housekeeping can help reduce the indoor levels of particulate matter present in the air and on surfaces. Over time, airborne particulate levels will decrease, but there are some things that can be done to maximize the comfort and health of employees. Housekeeping staff should be instructed to only use HEPA (high efficiency particulate air) vacuum cleaners so that fine particles are not reintroduced into the air. Carpets, upholstery, and other porous materials should be thoroughly HEPA vacuumed or professionally cleaned. Nonporous surfaces including walls and floors should be cleaned using wet methods where feasible.