Indoor air pollution major risk to health

What is ventilation like in your workplace? Do workers have headaches, eye irritation or respiratory problems? Do they complain about cigarette smoke, bad odours, humidity or poor air circulation?

Indoor air pollution is one of the top five environmental risks to public health, according to the US Environment Protection Agency.

Meanwhile, the Occupational Safety and Health Administration (OSHA) in the US recently published guidelines for indoor air quality (IAQ) investigations, which includes guidelines for employers to prevent or manage IAQ problems in the workplace.

It notes that energy conservation measures have reduced the infiltration of outside air into modern office buildings and that poor IAQ can lead to symptoms like headaches, feeling dizzy, poor concentration, fatigue, nausea and irritation to the eye, nose and throat.

It says that in some 500 IAQ investigations by the US National Institute for Occupational Safety and Health over 10 years the primary causes of IAQ problems were: inadequate ventilation (52 per cent); contamination from inside building (16 per cent); contamination from outside building (10 per cent); microbial contamination (5 per cent); contamination from building fabric (4 per cent); and unknown sources (13 per cent).

Symptoms arising from "sick building syndrome", like headache, nausea, dermatitis, irritation to the eye, nose or throat, coughing, muscle pain, fatigue and respiratory irritation "often disappear after the worker leaves the worksite", says OSHA.

The publication lists major indoor air contaminants and notes that "tobacco smoke is a major contributor to indoor air quality problems" as it contains several hundred toxic substances including carbon monoxide, nitrogen dioxide and formaldehyde.

Tobacco smoke from cigars, cigarettes and pipe tobacco can particularly affect allergic or asthmatic people, leading to "eye and nasal irritation, coughing, wheezing, sneezing, headache, and related sinus problems".

Tobacco smoke can also burn, itch or tear the eyes of people with contact lenses. Indeed, the study notes that "most indoor air particulates are due to tobacco smoke and are in the respirable range". Biological contaminants in the workplace include viruses, bacteria, fungi, pollen, mould, dander and mites, says OSHA.

These can come from condensation in air handling systems, water damaged materials such as carpets, areas of high humidity in the workplace, hot water systems, plants, animal droppings, food and food products. These can cause humidifier fever, allergic rhinitis and legionellosis (Legionnaires' disease), causing workers symptoms such as chills, fever, muscle ache, chest tightness, headache, cough, sore throat, diarrhoea, and nausea.

Carbon monoxide arising from engine exhausts, poorly vented fossil fuel appliances and tobacco smoke can cause dizziness, headache, nausea, cardiovascular effects and death, says OSHA.

Formaldehyde, which can come from some foam insulation, plywood, carpets, glues, adhesives and tobacco smoke, can cause allergic reactions, rashes and eye, respiratory and mucous membrane irritation, it says.

Carbon dioxide, which can arise from unvented or poorly vented gas and kerosene appliances and human respiration (having too many people in too small a space), can lead to poor concentration and drowsiness.

The OSHA says employers should realise that "the most effective engineering control for prevention of indoor air quality problems is assuring an adequate supply of fresh outdoor air through natural or mechanical ventilation".

It recommends that employers use local exhaust ventilation to remove contaminants generated by industrial processes and that "room air in which contaminants are generated should be discharged directly outdoors rather than recirculated".

It says employers can improve ventilation by opening outdoor air-supply dampers and room airvents and using room fans "to improve mixing and dilution of pollutants". Employers should ensure that outside air intakes are not located close to potential sources of contamination, such as garages, building exhausts or roadways. Humidity should be between 20 per cent and 60 per cent and temperatures kept between 68 and 76 Fahrenheit. Filters on air handling units should be regularly replaced and air distribution ducts and dampers should be regularly cleaned, says OSHA.

Microbial contaminants can be eliminated or controlled by cleaning and repairing places where water has collected or leaked, such as floors, roofs or humidifiers with stagnant water. Damp insulation, mouldy ceiling tiles or mildewed carpets should be removed.

OSHA recommends that employers isolate areas of renovation, painting, carpet laying or pest control within the workplace and, if possible, to carry out such work during evenings or weekends.

Tobacco smoking should be banned or restricted "to designated areas which have their air discharged directly to the outdoor rather than recirculated".