Air Quality Program

New! Instructions for Woods #50016 Timer, Distributed by Plug at 20

Timer Instructions in English

Timer Instructions in Korean

Timer Instructions in Spanish

Timer Instructions in Tagalog

Winter Travel Tips:

  • Travel ready: you and your family may jump into a warm car dressed for work or school. But in the event of a breakdown or crash, you could spend a long period of time without heat. Wear warm clothes and boots and carry extra in the trunk.
  • Tire pressure is likely to drop when outdoor temperatures cool. 'Low' tires wear faster, decrease fuel mileage and are prone to flats. Correct tire pressure is vital for safe vehicle handling and long tire life. If you are adding air to your tires, avoid moisture from gathering in the tire valve where it can freeze and cause the valve to leak. Environment Canada recommeds letting some air out of each valve and blowing some air from the supply hose before filling tires to avoid adding moisture.
  • Start-up is a period of maximum engine wear and minimum fuel efficiency for cold engines. Emissions control equipment is very effective for warm engines but not useful until components have warmed.  A cold engine produces 50-100 times more pollution in the first minute after starting than one minute fully warmed.


Instructions for timers distributed in prior years:

Instructions for Woods 50016 (distributed January 2012)

Instructions for Woods 59382 (distributed in January 2011)

Instructions for Intermatic timers (distributed 2010 and earlier)  

Why Plug at 20 degrees?

To Reduce Engine Wear

Start-up is a period of maximum engine wear and minimum fuel efficiency. Cold oil circulates slowly, leaving engine components unprotected. Block heaters pre-heat engines, allowing them to reach operating temperature sooner and get lubrication to the moving parts. Heat is also available for cabs and windshields sooner - benefiting drivers.

To Reduce Air Pollution

A study performed by Sierra Research in Anchorage and Fairbanks compared emissions from vehicles at cold temperatures. The local testing established that use of block heaters substantially reduced start-up emissions and fuel consumption.

Carbon Monoxide Plugin Reduction Graph

To keep your neighborhood clean

On days with inversions and still air, pollution from vehicle cold starts and idling disperses very slowly.  Some of the highest CO levels in Anchorage are found during the morning hours in neighborhoods where traffic is low but many cars are started cold after parking outside overnight.  The encouragement to “Plug @ 20” is a reminder to plug even when vehicles start with relative ease.Engine Block Heaters

Link to municipal block heater page here

How long have block heaters been around? Are they used outside of Alaska?

Yes, block heaters were invented by Andrew Freeman, who was born in North Dakota in 1909.  To allow their Model A Ford to start, Freeman's family first heated their garage by woodstove to warm the car. The town's mail carrier drained oil from his engine after completing his route, kept it indoors overnight, and replaced it each morning. Other neighbors poured hot water over their intake manifolds or shoveled coals from the furnace onto the ground beneath their engines (yikes!). Freeman received a degree in electrical engineering in 1932, and made application of his skills by cobbling together the heating element from a clothes iron with coiled copper tubing. After successfully starting at 29 below zero, friends and neighbors pleaded for heaters.  The 'Freeman Electric Internal-Combustion Engine Head Bolt Heater' received a patent in 1949, and nearly a quarter million were sold in 28 states within four years.  Source: Prarie Public Radio and State Historical Society of North Dakota, by permission.  

 How else can I improve air quality?

  • Don’t be an SOV (single occupancy vehicle)!  For free, confidential rideshare matching for carpool or vanpool, call the Share-A-Ride program at 562-7665 or register to find your carpool partner online at
  • Forget the window scraping and slippery streets; take the bus to work or use it for errands during the day and keep your parking place.Visit for your travel choices.  People Mover's "Bus Tracker" allows you to view nearly to the minute where the bus is on each route via computer or smartphone.     
  • Minimize the number of cold starts you make by ‘linking’ your trips.  Combining errands can reduce your travel miles and cold start pollution.
  • Maintain your car for better startability, mileage, emissions and wear.
  • Businesses, organizations and schools can work toward a Green Star Award by reducing solid waste, energy and air emissions from travel and operations. See


Contact Us

Environmental Services Division Department of Health and Human Services
825 L Street PO Box 196650 Anchorage AK 99519-6650 Phone: 907-343-4200
TTY: 907-343-4797
How Can We Help You?

Timer Configuration 

Typical in-use configuration for a timer (above)

How much does it cost to use a block heater?

A car with a 400 watt heater uses less than 15 cents in electricity for a two to three hour plug (2010 residential rate).  Most of this cost can be offset by allowing the idle time to be reduced, resulting in a gas savings.

Emissions can be reduced significantly by preheating just two to three hours prior to commute departure time, when cars have been parked overnight and engines are coldest.

Features to look for in a timer

As consumers become more energy conscious, timers are available for many more applications.  Which timers are best for use with block heaters? Packaging that includes words like 'heavy-duty', 'outdoor' and 'block heater' are good; look for 15 A (or AMP) resistive or greater and a 24-hour clock.  Avoid timers with photocells as these supply electricity during hours of darkness or until several hours after dark. Disqualifiers also include such wording as 'not for use with extension cords' and 'must be mounted 55 inches above the ground'.

To be sure your timer works as expected, try yours indoors with a radio or lamp.  When installing it outdoors, set the timer clock to actual time. Periodically check that the time on the clock is correct; power interruptions and very cold temperatures may disrupt or slow the timer clock.

2012 Air Quality telephone survey