How Bad Is Hazardous Air Quality?

Increased urban populations and intensified industrial activity have contributed to the increasingly serious problem of air quality over the last couple of centuries. Today, the problem is so pronounced that the World Health Organisation (WHO) even estimates that nine-tenths of the world’s population are exposed to unsafe levels of air quality on a daily basis!

In order to address the issue, governments around the globe have set up Air Quality Index (AQI) systems, which are specifically designed to collect and record concentrations of major pollutants. This not only provides a yardstick against which past and future performance can be measured, but also gives concerned citizens access to up-to-the-minute knowledge of the air quality in their area, allowing them to make informed decisions about travel, leisure and other outdoor activities.

The US AQI is widely regarded as one of the most comprehensive and authoritative systems in the world. According to their six-tiered, colour-coded framework for air quality, the top level (and thus most polluted) category is branded “Hazardous”. But how have they arrived at such a definition – and what does it mean for human health?

What is “Hazardous” air quality?

In the United States, the national AQI system relies upon data collected and collated by the Environmental Protection Agency (EPA). This data is gathered via a number of different sources, including a sophisticated and expansive network of ground-level sensors and the most advanced satellite imaging equipment in outer space.

Once the information has been assimilated into one place, it is then quantified by the concentration of five of the most dangerous pollutants known to man. These are, in no particular order, particulate matter, ground-level ozone, carbon monoxide, nitrogen dioxide and sulphur dioxide. Where more than one contaminant is found in a particular location, the higher reading is used to determine the site’s AQI value.

The top level of air pollution is labelled “Hazardous” by the EPA and is colour-coded maroon, so that interested parties can see at a glance whether they are adversely affected by poor air quality. “Hazardous” air is that which is quantified at between 301 and 500 on the US AQI scale; for context, anything over 100 is deemed to be “Unhealthy” to at least some sections of the population.

What are the effects of exposure to “Hazardous” air quality?

The insidious and long-lasting impacts of exposure to air pollution make it difficult to explain how hazardous air quality affects human health in a nutshell. Suffice it to say that in mild cases, hazardous air quality will result in coughing, itchiness and irritation of the throat and poor visibility. In more extreme circumstances, exposure to hazardous air pollution will trigger respiratory diseases and can cause loss of consciousness, coma and even death.

Of course, it goes without saying that vulnerable segments of the population – such as the very old, the very young and those who have already been diagnosed with a pulmonary or cardiovascular disease – will experience the ill-effects of hazardous contamination more keenly. As such, it’s highly advisable that these individuals avoid pollution hotspots, though doing so is a good idea for everyone.

Most developed countries in the West are highly fortunate in that they rarely (if ever) experience hazardous levels of air quality, thanks in part to the modern monitoring infrastructures that they have in place. However, the occurrence is a fairly common one in more impoverished and developing parts of the globe. Asia, in particular, struggles with poor air quality, with China, India and Bangladesh all home to many cities that regularly suffer hazardous concentrations of pollutants.

For more information on the topic of air pollution and the means by which it is measured, the upcoming Air Quality and Emissions (AQE) show will provide superb insight into the latest developments in the industry. Scheduled to take place this October in Telford in the UK, the event is open to all those who are interested and more details can be found at the above link.