Air quality in Autumn - are you aware of the effects?

We are often asked the question: “Are the effects of air pollution worse in winter or summer?” This is a complex question as the air we breathe is affected by many different factors including the nature of the sources of air pollution, the weather, our proximity to emission sources and whether we spend our time in locations that trap pollutants. Additionally, it’s not just the effect on humans we need to consider; vegetation is also affected by air pollution, and this can have far-reaching consequences for diversity in the natural environment.

What changes in Autumn?

Moving into autumn, the days are starting to get shorter and cooler and as we spend more time indoors our need for power to provide heating and lighting generally increases. Sources of power that are reliant on fuel combustion emit pollutants into the air, and as our power usage increases so will these emissions. So while we may spend more time inside and away from outdoor emission sources, we may still be exposed indoors. And, unfortunately how protected we are from outdoor polluted air being brought inside, depends on how well we ventilate our spaces.

Additionally, the changing weather can encourage more of us to jump in our cars rather than brave the journey on foot or bicycle. More cars on the road means more emissions. And though you may expect you would be protected from these emissions whilst inside the vehicle, some studies suggest that concentrations of pollutants inside cars can be more than 15 times of that outside the car! This is because while car air filtration systems are relatively good at screening out larger particles, small particles and gases are still able to find their way in; meaning exhaust emissions recirculate and accumulate within the confined space.

Finally, a key autumnal event with the potential for emissions is fireworks night. This often leads to some substantial increases in pollutant concentrations for short periods.

How the weather can affect air quality?

A key feature of our autumn weather in the UK is an increase in low pressure systems which brings lower temperatures, a greater frequency of high winds and more rain. Taking each of these in turn:

• For ‘hot’ emissions, the larger difference in temperature between the hot gases and the cooler, surrounding air can be significant and mean that plumes of pollution are more buoyant, rising further from the ground and taking pollutants further away from the air that we are breathing.
• High winds can increase dispersion of pollutants. This can have both positive and negative effects depending on whether polluted air is being carried towards or away from areas that are sensitive to air pollution.
• Increased rainfall can also mean that pollution is deposited onto surfaces rather than remaining in the air.

What does this mean?

Measurements of pollutant concentrations tend to indicate that air quality over the entire autumn season does not stand out as being exceptionally good or bad. Instead what we see is a balance between the negative impact of increases in emissions and the largely positive impacts associated with the changes in weather.

How can you make a difference?

At all times of the year it’s important to be aware of the risks and protect yourself where you can. To help, we are sharing three things you can do to reduce emissions and protect yourself and those around you.

Change the way you travel:

• Avoid making car journeys if you can – walk or cycle to reap the health benefits!
• If you can’t avoid a car journey, try to travel smarter by combining several journeys into one trip.
• Switch off your car engine when stationary.
• Keep tyres properly inflated and vehicles maintained.
• Drive smoothly – avoid hard acceleration and anticipate braking (even electric cars emit brake particles).

Consider how you heat your home and cook:

• Use electrically-powered appliances where possible – followed by gas. Avoid wood-burning.

Reduce exposure inside your home:

• If you have to use household sprays, cleaners, paints etc. then ventilate rooms well during and after.
• Avoid burning scented candles.